Generation and Detection of Reactive Oxygen Species in Photocatalysis

Amplifying chlorinated phenol decomposition via Dual-Pathway O2 Activation: The impact of zirconium loading on BiOCl

The effectiveness of photocatalytic molecular oxygen (O2) activation in pollutant removal relies on the targeted production of reactive oxygen species (ROS). Herein, we demonstrate the dual-pathway activation of O2 on BiOCl through zirconium (Zr) loading. The incorporation of Zr onto the surface of BiOCl not only leads to an increased generation of oxygen vacancies (OV) but also fosters a coupling between the d electrons of Zr and OV, forming dual-active sites known as Zr-oxygen vacancies (Zr-OV). Generally, OV adsorbs O2 and transfers one electron directly to form superoxide radicals (•O2-). Contrary to the conventional single-electron direct activation of O2 to form •O2-, Zr-OV exhibits more flexible coordination and superior electron-donating capabilities. It facilitates O2 conversion to peroxide radicals (O22-) and enables the subsequent generation of •O2- from O22-, significantly promotes the dechlorination and mineralization efficiency of chlorophenol under visible light. This study presents a straightforward strategy to precisely regulate ROS production by expanding pathways, shedding light on the critical role of managing ROS generation for effective pollutant purification.

Persistent production of multiple active species with copper doped zinc gallate nanoparticles for light-independent photocatalytic degradation of organic pollutants

Photocatalysis is considered as an environmentally friendly and sustainable method as it can produce active species to degrade pollutants. However, its applications are hindered by the turbidity of pollutants and the requirements for continuous or repeated in situ irradiation. To avoid the need for continuous in situ irradiation in the photocatalytic process, herein we report the doping of Cu(II) ions into zinc gallate (ZnGa2O4) as traps to capture photo-generated electrons. In this way, long lifetime charge release and separation were effectively achieved for the persistent degradation of organic dyes in wastewater. The Cu(II) doped ZnGa2O4 (ZGC) nanoparticles with a small size about 7.7 nm synthesized via a hydrothermal method exhibited a persistent photocatalytic activity with continuous production of reactive oxygen species for at least 96 h without in situ irradiation due to its unique electronic structure and carrier transport path, and enabled to degrade 82.2 % of rhodamine B in 1 h. Further investigation revealed that the doped Cu(II) ions occupied the octahedral sites of ZGC and highly increased the persistent production and availability of active species for the persistent degradation of organic dyes under pre-illuminated conditions.

Homochiral light-sensitive metal-organic framework photoelectrochemical gated transistor for enantioselective discrimination of monosaccharides

As pure antipodes may differ in biological interactions, pharmacology, and toxicity, discrimination of enantiomers is important in the pharmaceutical and agrochemical industries. Two major challenges in enantiomer determination are transducing and amplifying the distinct chiral-recognition signals. In this study, a light-sensitive organic photoelectrochemical transistor (OPECT) with homochiral character is developed for enantiomer discrimination. Demonstrated with the discrimination of glucose enantiomers, the photoelectrochemically active gate electrode is prepared by integrating Au nanoparticles (AuNPs) and a chiral Cu(II)-metal-organic framework (c-CuMOF) onto TiO2 nanotube arrays (TNT). The captured glucose enantiomers are oxidized to hydrogen peroxide (H2O2) by the oxidase-mimicking AuNPs-loaded c-CuMOF. Based on the confinement effect of the mesopocket structure of the c-CuMOF and the remarkable charge transfer ability of the 1D nanotubular architecture, variations in H2O2 yield are translated into significant changes in OPECT drain currents (ID) by inducing a catalytic precipitation reaction. Variations in ID confer a sensitive discrimination of glucose enantiomers with a limit of detection (LOD) of 0.07 μM for L-Glu and 0.05 μM for D-Glu. This enantiomer-driven gate electrode response strategy not only provides a new route for enantiomer identification, but also helps to understand the origin of the high stereoselectivity in living systems.

Single Mn atom modulated molecular oxygen activation over TiO2 for photocatalytic formaldehyde oxidation

In single-atom catalysts, the atomically dispersed metal sites are pivotal for oxygen molecule activation. We hypothesize that dispersing single Mn atoms on TiO2 nanosheets may improve the photocatalytic oxidation of formaldehyde (HCHO) in the gas phase under ambient conditions. Density function theory (DFT) and experimental experiments were carried out to single Mn atoms not only improved the transfer of localized electrons and photogenerated electrons but also enhanced the activation/dissociation of O2 to generate monoatomic oxygen ions (O-) as the final reactive oxygen species (ROS). In photocatalytic experiments, Mn/TiO2 photocatalyst removed 100 % of HCHO at a low concentration of 7.6 ppm, and reaching excellent mineralization efficiency of over 99.6 %. According to the proposed reaction mechanism, O2 spontaneously adsorbs onto the Mn/TiO2 surface, forming two adsorbed O- after electron donation into the π2p* antibonding orbitals of O2. The adsorbed O- then reacts with gaseous HCHO to produce the key intermediate dioxymethylene (DOM), finally fulfilling a more favorable oxidation process on the Mn/TiO2 surface. This research illustrates the key role of O- in HCHO oxidation and paves the way for practical HCHO removal using TiO2-based photocatalysts.

Time-resolved spectroscopic investigation for the practical application of a photocatalytic air purifier

The photocatalytic efficiency for removing volatile organic compounds (VOCs) is significantly influenced by operational parameters like humidity and flow velocity, exhibiting notable and inconsistent fluctuations in both lab-scale and large-scale demonstrations. In this study, operando spectroscopy and isotope analysis were employed to investigate the correlation between humidity levels and degradation of gaseous acetaldehyde using TiO2 photocatalysts, aiming to demonstrate the scaling-up of photocatalytic air purifier. It was observed that rate constants for the mineralization of acetaldehyde rapidly decreased by 30% as relative humidity increased from 25% to 80% in the flow system (with an air velocity, v = 0.78 m/s). However, batch system showed smaller change with only a 10% reduction of the rate constant. Humidity fluctuations were more pronounced under high-speed conditions and were amplified in air purifier (v = 3.8 m/s). Time-resolved operando spectroscopy using an 13C isotope of acetaldehyde revealed that humidity's distinct role in dark adsorption and photocatalytic reactions. Water was found to inhibit the formation of crotonaldehyde during aldol condensation reaction in dark condition. Moreover, water suppressed photocatalytic mineralization by inhibiting acetate oxidation to formate. These findings provide valuable insights for improving realistic air purification processes, underscoring the importance of identifying key intermediates and controlling humidity to enhance the selectivity of gaseous pollutant oxidation reactions.

Fabrication and characterization of binary composite MgO/CuO nanostructures for the efficient photocatalytic ability to eliminate organic contaminants: A detailed spectroscopic analysis

Design and eco-friendly fabrication of affordable and sustainable materials for the treatment of wastewater consisting of dyes, antibiotics, and other harmful substances has always been demanding. Untreated wastewater being released from industries imposes serious threats to our ecosystem, seeking convenient approaches to diminish this alarming issue. Here in this work, we synthesized MgO/CuO nanocomposites from a plant extract of Ammi visnaga L. and then employed these nanocomposites for the treatment of organic dye (methylene blue). We characterized the synthesized nanocomposites by dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). DLS presented information about the explicit size of nanocomposites, while the surface charge was examined by zeta potential. XRD provided detailed information about the crystalline behavior and the information regarding surface morphology and size was extracted by SEM, TEM, and AFM. Moreover, the fabricated nanocomposites were used as a photocatalyst in the treatment of methylene blue. The overall catalytic reaction took an hour to complete, and the value of percentage degradation was 98 %. Substantially, a detailed account of the kinetics, rate of reaction, and mechanism is also fostered in the context. The presented study can assist scientists and researchers around the world to reproduce the results and use them to apply them on a broader scale.

Selective oxidation of β-keto ester modulated by the d-band centers in D-A conjugated microporous metallaphotoredox catalysts containing M-salen (MZn, Cu and Co) and triazine monomers

Photocatalytic selective oxidation plays an important role in developing green chemistry. However, it is challenging to design an efficient photocatalyst for controlling the selectivity of photocatalytic oxidation reaction and exploring its detailed mechanism. Here, we synthesized three conjugated microporous polymers (CMPs) with D-A structures, named M-SATE-CMPs (MZn, Cu and Co), with different d-band centers based on different metal centers, resulting in the discrepancy in adsorption and activation capacities for the reactants, which produces the selectivity of β-keto esters being catalyzed into α-hydroperoxide β-keto esters (ROOH) or to α-hydroxyl β-keto esters (ROH). Density functional theory (DFT) calculations also demonstrate that the adsorption and activation capacities of the metal active centers in M-SATE-CMPs (MZn, Cu and Co) for ROOH are the key factors to influence the photocatalytic selective oxidation of β-keto ester. This study provides a promising strategy for designing a metallaphotoredox catalyst whose photocatalytic selectivity depends on the d-band center of metal site in the catalyst.

Particles-involved photochemical processes: A review for the case of mercury reduction in relation to aquatic mercury cycling

Mercury (Hg) is one of the toxic metals of global and environmental concern, with aquatic Hg cycling being central in determining the production of highly toxic methylmercury and the air-water Hg exchange influencing the long-range intercontinental atmospheric Hg transport. Both inorganic and organic forms of Hg can be bound by suspended particles, including inorganic minerals (in particular metal oxides/sulfides) and particulate organic matter. Photochemical transformation is a critical process in surface water, and the role of suspended particles in Hg redox photoreactions has increasingly emerged, albeit in limited studies in comparison to extensive studies on aqueous (homogeneous) photoreactions of Hg. The lack of understanding of what roles suspended particles play might result in inaccurate estimation of how Hg species transform and/or cycle in the environment. In view of this gap, this paper critically reviews and synthesizes information on the studies conducted on different natural surface waters with respect to the potential roles of suspended particles on Hg photo-redox reactions. It robustly discusses the various possible pathways and/or mechanisms of particle-mediated Hg (II) reduction, in enhancing or lowering the production of dissolved gaseous mercury. These processes include photo hole-electron pair formation and reactive oxygen species generation from particle excitation and their involvement in Hg photoreduction, in addition to the light attenuation effect of particles. This paper highlights the necessity of future studies exploiting these particles-mediated Hg photoreactions pathways and the implications of including these heterogeneous photoreactions (together with particulate elemental Hg species) on the air-water Hg exchange estimation.

Cu@CuOx/WO3 with photo-regulated singlet oxygen and oxygen adatoms generation for selective photocatalytic aromatic amines to imines

Photocatalysts can absorb light and activate molecular O2 under mild conditions, but the generation of unsuitable reactive oxygen species often limits their use in synthesizing fine chemicals. To address this issue, we disperse 1 wt% copper on tungsten trioxide (WO3) support to create an efficient catalyst for selective oxidative coupling of aromatic amines to imines under sunlight irradiation at room temperature. Copper consists of a metallic copper core and an oxide shell. Experimental and density functional theory calculations have confirmed that Cu2O is the primary activation site. Under λ < 475 nm, the light excites electrons of the valence bands in Cu2O and WO3, which activate O2 to superoxide radical •O2-. Then rapidly transforms into oxygen adatoms (•O) and oxygen anion radicals (•O-) species on the surface of Cu2O. Simultaneously, it is captured by holes in the WO3 valence band to generate singlet oxygen (1O2). •O bind to 1O2 promoting the coupling reaction of amines. When λ > 475 nm, intense light absorption due to the localized surface plasmon resonance excites numerous electrons in Cu to promote the oxidative coupling with the adsorbed O2. This study presents a promising approach towards the design of high-performance photocatalysts for solar energy conversion and environmentally-friendly oxidative organic synthesis.

3D/1D Fe3O4@TiO2/TC-TiO2/SiO2 Magnetic Inorganic-Framework Molecularly Imprinted Fibers for Targeted Photodegradation

To achieve a selective degradation of pollutants in a water body, 3D/1D magnetic molecularly imprinted fibers Fe3O4@TiO2/TC-TiO2/SiO2 were fabricated by an electrospinning method. The molecularly imprinted layer was successfully prepared by a direct imprinting method using TiO2 as a functional monomer. Fe3O4 facilitates the catalyst recovery and light utilization. The as-prepared fibrous photocatalyst has a large specific surface area of 132.4 m2/g. The successful generation of imprinted sites was proven by various characterizations. The weak interaction between the inorganic functional monomer and tetracycline (TC) was determined to be van der Waals force and hydrogen bonds by the IGMH isosurface theory. The construction of the 3D/1D homojunction of molecularly imprinted materials is beneficial to charge transfer. The as-prepared photocatalyst exhibits a high selectivity coefficient α = 737.38 competing with RhB. The TC removal efficiency reached 100% within only 20 min. In addition, the possible degradation pathway and the degradation mechanism are reasonably proposed. This work not only provides an in-depth mechanism of the weak interaction between the inorganic molecularly imprinted functional monomer and pollutant molecules but also offers new thoughts on the fabrication of photocatalysts for the effective and selective treatment of pollutants in water bodies.

Iron single atoms anchored on ultrathin carbon nitride photocatalyst for visible light-driven water decontamination

Graphitic carbon nitride has gained considerable attention as a visible-light photocatalyst. However, its photocatalytic efficiency is restricted by its limited capacity for absorbing visible light and swift recombination of charge carriers. To overcome this bottleneck, we fabricated an atomic Fe-dispersed ultrathin carbon nitride (Fe-UTCN) photocatalyst via one-step thermal polymerization. Fe-UTCN showed high efficiency in the photodegradation of acetaminophen (APAP), achieving > 90 % elimination within 60-min visible light irradiation. The anchoring of Fe atoms improved the photocatalytic activity of UTCN by narrowing the bandgap from 2.50 eV to 2.33 eV and suppressing radiative recombination. Calculations by density functional theory revealed that the Fe-N4 sites (adsorption energy of - 3.10 eV) were preferred over the UTCN sites (adsorption energy of - 0.18 eV) for the adsorption of oxygen and the subsequent formation of O2•-, the dominant reactive species in the degradation of APAP. Notably, the Fe-UTCN catalyst exhibited good stability after five successive runs and was applicable to complex water matrices. Therefore, Fe-UTCN, a noble-metal-free photocatalyst, is a promising candidate for visible light-driven water decontamination.

MoS2@MWCNTs with Rich Vacancy Defects for Effective Piezocatalytic Degradation of Norfloxacin via Innergenerated-H2O2: Enhanced Nonradical Pathway and Synergistic Mechanism with Radical Pathway

Molybdenum disulfide (MoS2)-based materials for piezocatalysis are unsatisfactory due to their low actual piezoelectric coefficient and poor electrical conductivity. Herein, 1T/3R phase MoS2 grown in situ on multiwalled carbon nanotubes (MWCNTs) was proposed. MoS2@MWCNTs exhibited the interwoven morphology of thin nanoflowers and tubes, and the piezoelectric response of MoS2@MWCNTs was 4.07 times higher than that of MoS2 via piezoresponse force microscopy (PFM) characterization. MoS2@MWCNTs exhibited superior activity with a 91% degradation rate of norfloxacin (NOR) after actually working 24 min (as for rhodamine B, reached 100% within 18 min) by pulse-mode ultrasonic vibration-triggered piezocatalysis. It was found that piezocatalysis for removing pollutants was attributed to the synergistic effect of free radicals (•OH and O2•-) and nonfree radical (1O2, key role) pathways, together with the innergenerated-H2O2 promoting the degradation rate. 1O2 can be generated by electron transfer and energy transfer pathways. The presence of oxygen vacancies (OVs) induced the transformation of O2 to 1O2 by triplet energy transfer. The fast charge transfer in MoS2@MWCNTs heterostructure and the coexistence of sulfur vacancies and OVs enhanced charge carrier separation resulting in a prominent piezoelectric effect. This work opens up new avenues for the development of efficient piezocatalysts that can be utilized for environmental purification.

A Sacrificial Linker in Biodegradable Polyesters for Accelerated Photoinduced Degradation, Monitored by Continuous Atline SEC Analysis

Polymeric materials that undergo photoinduced degradation have wide application in fields such as controlled release. Most methods for photoinduced degradation rely on the UV or near-UV region of the electromagnetic spectrum; however, use of the deeply penetrating and benign wavelengths of visible light offers a multitude of advantages. Here we report a lactone monomer for ring-opening copolymerizations to introduce a sacrificial linker into a polymer backbone which can be cleaved by reactive oxygen species which are produced by a photocatalyst under visible light irradiation. We find that copolymers of this material readily degrade under visible light. We followed polymer degradation using a continuous flow size exclusion chromatography system, the components of which are described herein.

Aerobic Oxidative Carboxylation of Styrene Over Cobalt Catalysts: Integrated CO2 Capture and Conversion

The direct synthesis of cyclic carbonates through oxidative carboxylation of alkenes using CO2 and O2 offers a sustainable and carbon-neutral method for CO2 utilization, which is, however, still a largely unexplored field. Here we develop a single-atom catalyst (SAC) Co-N/O-C as the earth-abundant metal catalyst for the oxidative carboxylation of styrene with CO2 and O2. Remarkably, even using the flue gas as an impure CO2 and O2 source, desired cyclic carbonate could be obtained with moderate productivity, which shows the potential for integrated CO2 capture and conversion, leveraging the high CO2 adsorption capacity of Co-N/O-C. In addition, the catalyst can be reused five times without an obvious decline in activity. Detailed characterizations and theoretical calculations elucidate the crucial role of single Co atoms in activating O2 and CO2, as well as controlling selectivity.

Ba2+-doping introduced piezoelectricity and efficient Ultrasound-Triggered bactericidal activity of brookite TiO2 nanorods

Exploring highly efficient ultrasound-triggered catalysts is pivotal for various areas. Herein, we presented that Ba2+ doped brookite TiO2 nanorod (TiO2: Ba) with polarization-induced charge separation is a candidate. The replacement of Ba2+ for Ti4+ not only induced significant lattice distortion to induce polarization but also created oxygen vacancy defects for facilitating the charge separation, leading to high-efficiency reactive oxygen species (ROS) evolution in the piezo-catalytic processes. Furthermore, the piezocatalytic ability to degrade dye wastewater demonstrates a rate constant of 0.172 min-1 and achieves a 100 % antibacterial rate at a low dose for eliminating E. coli. This study advances that doping can induce piezoelectricity and reveals that lattice distortion-induced polarization and vacancy defects engineering can improve ROS production, which might impact applications such as water disinfection and sonodynamic therapy.

Direct Photocatalytic Methane Oxidation to Formaldehyde by N Doping Co-Decorated Mixed Crystal TiO2

In this paper, N-doped TiO2 mixed crystals are prepared via direct calcination of TiN for highly selective oxidation of CH4 to HCHO at room temperature. The structures of the prepared TiO2 samples are characterized to be N-doped TiO2 of anatase and rutile mixed crystals. The crystal structures of TiO2 samples are determined by XRD spectra and Raman spectra, while N doping is demonstrated by TEM mapping, ONH inorganic element analysis, and high-resolution XPS results. Significantly, the production rate of HCHO is as high as 23.5 mmol·g-1·h-1 with a selectivity over 90%. Mechanism studies reveal that H2O is the main oxygen source and acts through the formation of ·OH. DFT calculations indicate that the construction of a mixed crystal structure and N-doping modification mainly act by increasing the adsorption capacity of H2O. An efficient photocatalyst was prepared by us to convert CH4 to HCHO with high yield and selectivity, greatly promoting the development of the photocatalytic CH4 conversion study.

Mechanistic study of visible light driven photocatalytic degradation of clofibric acid using Fe-based metal organic frameworks (MOFs)

Although a series of past studies proved the potential usage of Fe-based metal-organic frameworks (MOFs) as photocatalysts, there remains a knowledge gap of the photocatalytic mechanism stemming from the challenge to separate the simultaneous sorption and photocatalytic degradation. Thus, this article aimed to suggest a novel approach by desorbing target molecules during photocatalysis to excavate the underlying mechanisms of sorption and photocatalytic degradation. In this study, two Fe-based MOFs, MIL-101(Fe) and MIL-101(Fe)-NH2, were selected to remove clofibric acid under visible light irradiation. Prior to photocatalysis, sorption mechanism was uncovered based on the sorption kinetic, isotherm, thermodynamic interpretation, and of its dependence on solution pH. The results inferred that the primary sorption mechanism was through the π-π interaction between the benzene ring of clofibric acid and the organic ligand of Fe-based MOFs. Based on these results, photocatalytic mechanism could be independently or jointly assessed during the photocatalytic degradation of clofibric acid. Subsequently, the application of the Tauc method and XPS spectra revealed that the bandgap structure of Fe-based MOFs had the potential to oxidize clofibric acid by producing ROS through the electron excitation upon visible-light illumination. On top of that, the amine functionalization of Fe-based MOF altered the structural moiety that led to an additional strong acid-base interaction with clofibric acid but a decrease in the bandgap limiting the ROS production during photocatalytic activity.

Mechanisms on the removal of gram-negative/positive antibiotic resistant bacteria and inhibition of horizontal gene transfer by ferrate coupled with peroxydisulfate or peroxymonosulfate

The existence of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has been a global public environment and health issue. Due to the different cell structures, gram-positive/negative ARB exhibit various inactivation mechanisms in water disinfection. In this study, a gram-negative ARB Escherichia coli DH5α (E. coli DH5α) was used as a horizontal gene transfer (HGT) donor, while a gram-positive ARB Bacillus as a recipient. To develop an efficient and engineering applicable method in water disinfection, ARB and ARGs removal efficiency of Fe(VI) coupled peroxydisulfate (PDS) or peroxymonosulfate (PMS) was compared, wherein hydroxylamine (HA) was added as a reducing agent. The results indicated that Fe(VI)/PMS/HA showed higher disinfection efficiency than Fe(VI)/PDS/HA. When the concentration of each Fe(VI), PMS, HA was 0.48 mM, 5.15 log E. coli DH5α and 3.57 log Bacillus lost cultivability, while the proportion of recovered cells was 0.0017 % and 0.0566 %, respectively, and HGT was blocked. Intracellular tetA was reduced by 2.49 log. Fe(IV) and/or Fe(V) were proved to be the decisive reactive species. Due to the superiority of low cost as well as high efficiency and practicality, Fe(VI)/PMS/HA has significant application potential in ARB, ARGs removal and HGT inhibition, offering a new insight for wastewater treatment.

Adavosertib-encapsulated metal-organic frameworks for p53-mutated gallbladder cancer treatment via synthetic lethality

Adavosertib (ADA) is a WEE1 inhibitor that exhibits a synthetic lethal effect on p53-mutated gallbladder cancer (GBC). However, drug resistance due to DNA damage response compensation pathways and high toxicity limits further applications. Herein, estrone-targeted ADA-encapsulated metal-organic frameworks (ADA@MOF-EPL) for GBC synthetic lethal treatment by inducing conditional factors are developed. The high expression of estrogen receptors in GBC enables ADA@MOF-EPL to quickly enter and accumulate near the cell nucleus through estrone-mediated endocytosis and release ADA to inhibit WEE1 upon entering the acidic tumor microenvironment. Ultrasound irradiation induces ADA@MOF-EPL to generate reactive oxygen species (ROS), which leads to a further increase in DNA damage, resulting in a higher sensitivity of p53-mutated cancer cells to WEE1 inhibitor and promoting cell death via conditional synthetic lethality. The conditional factor induced by ADA@MOF-EPL further enhances the antitumor efficacy while significantly reducing systemic toxicity. Moreover, ADA@MOF-EPL demonstrates similar antitumor abilities in other p53-mutated solid tumors, revealing its potential as a broad-spectrum antitumor drug.

Advanced oxidation processes for water and wastewater treatment - Guidance for systematic future research

Advanced oxidation processes (AOPs) are a growing research field with a large variety of different process variants and materials being tested at laboratory scale. However, despite extensive research in recent years and decades, many variants have not been transitioned to pilot- and full-scale operation. One major concern are the inconsistent experimental approaches applied across different studies that impede identification, comparison, and upscaling of the most promising AOPs. The aim of this tutorial review is to streamline future studies on the development of new solutions and materials for advanced oxidation by providing guidance for comparable and scalable oxidation experiments. We discuss recent developments in catalytic, ozone-based, radiation-driven, and other AOPs, and outline future perspectives and research needs. Since standardized experimental procedures are not available for most AOPs, we propose basic rules and key parameters for lab-scale evaluation of new AOPs including selection of suitable probe compounds and scavengers for the measurement of (major) reactive species. A two-phase approach to assess new AOP concepts is proposed, consisting of (i) basic research and proof-of-concept (technology readiness levels (TRL) 1-3), followed by (ii) process development in the intended water matrix including a cost comparison with an established process, applying comparable and scalable parameters such as UV fluence or ozone consumption (TRL 3-5). Subsequent demonstration of the new process (TRL 6-7) is briefly discussed, too. Finally, we highlight important research tools for a thorough mechanistic process evaluation and risk assessment including screening for transformation products that should be based on chemical logic and combined with complementary tools (mass balance, chemical calculations).

Abiotic Methane Production Driven by Ubiquitous Non-Fenton-Type Reactive Oxygen Species

Abiotic CH4 production driven by Fenton-type reactive oxygen species (ROS) has been confirmed to be an indispensable component of the atmospheric CH4 budget. While the chemical reactions independent of Fenton chemistry to ROS are ubiquitous in nature, it remains unknown whether the produced ROS can drive abiotic CH4 production. Here, we first demonstrated the abiotic CH4 production at the soil-water interface under illumination. Leveraging this finding, polymeric carbon nitrides (CNx) as a typical analogue of natural geobattery material and dimethyl sulfoxide (DMSO) as a natural methyl donor were used to unravel the underlying mechanisms. We revealed that the ROS, photocatalytically produced by CNx, can oxidize DMSO into CH4 with a high selectivity of 91.5 %. Such an abiotic CH4 production process was further expanded to various non-Fenton-type reaction systems, such as electrocatalysis, pyrocatalysis and sonocatalysis. This work provides insights into the geochemical cycle of abiotic CH4, and offers a new route to CH4 production via integrated energy development.

Oxidative photocatalysis on membranes triggers non-canonical pyroptosis

Intracellular membranes composing organelles of eukaryotes include membrane proteins playing crucial roles in physiological functions. However, a comprehensive understanding of the cellular responses triggered by intracellular membrane-focused oxidative stress remains elusive. Herein, we report an amphiphilic photocatalyst localised in intracellular membranes to damage membrane proteins oxidatively, resulting in non-canonical pyroptosis. Our developed photocatalysis generates hydroxyl radicals and hydrogen peroxides via water oxidation, which is accelerated under hypoxia. Single-molecule magnetic tweezers reveal that photocatalysis-induced oxidation markedly destabilised membrane protein folding. In cell environment, label-free quantification reveals that oxidative damage occurs primarily in membrane proteins related to protein quality control, thereby aggravating mitochondrial and endoplasmic reticulum stress and inducing lytic cell death. Notably, the photocatalysis activates non-canonical inflammasome caspases, resulting in gasdermin D cleavage to its pore-forming fragment and subsequent pyroptosis. These findings suggest that the oxidation of intracellular membrane proteins triggers non-canonical pyroptosis.

Unraveling the Impact of Adsorbed Molecules on Photocatalytic Processes: Advancements in Understanding Facet-Controlled Semiconductor Photocatalysts

This work aims to demonstrate that the Fe2O3 nanocrystals' adsorptive and photocatalytic properties can be adjusted by exposing the crystal facets that are functionalized. To this end, cube- and disc-like structures were synthesized using a metal ion-mediated hydrothermal route. Thereafter, some of the samples were annealed at 500 °C for 3 h. Our paper combines the experimental part with theoretical calculations of the obtained materials' band edge positions. The results reveal that-aside from hematite-the as-synthesized discs also contain γ-FeOOH and β-Fe2O3 phases, which transform into α-Fe2O3 during annealing. The hydrodynamic diameter, zeta potential, and adsorption kinetics measurements show that the cube-like samples exhibit the highest affinity for cationic, whereas the discs have an affinity for anionic dye. Measurements of the wall zeta potential also reveal that annealing the discs modifies their surface state and ability to adsorb molecules. Photocatalytic tests show that the as-synthesized powders have better photocatalytic performance toward methylene blue decomposition than the annealed ones. The observed small changes in the concentration of the MO during illumination result from the energy band structure of the cube-like crystal orientation.

Nanogalvanic Cells Release Highly Reactive Electrons in Tumors to Effectively Eliminate Tumors

External stimuli triggering chemical reactions in cancer cells to generate highly reactive chemical species are very appealing for cancer therapy, in which external irradiation activating sensitizers to transfer energy or electrons to surrounding oxygen or other molecules is critical for generating cytotoxic reactive species. However, poor light penetration into tissue, low activity of sensitizers, and reliance on oxygen supply restrict the generation of cytotoxic chemical species in hypoxic tumors, which lowers the therapeutic efficacy. Here, this work presents galvanic cell nanomaterials that can directly release highly reactive electrons in tumors without external irradiation or photosensitizers. The released reactive electrons directly react with surrounding biomolecules such as proteins and DNA within tumors to destroy them or react with other surrounding (bio)molecules to yield cytotoxic chemical species to eliminate tumors independent of oxygen. Administering these nanogalvanic cells to mice results in almost complete remission of subcutaneous solid tumors and deep metastatic tumors. The results demonstrate that this strategy can further arouse an immune response even in a hypoxic environment. This method offers a promising approach to effectively eliminate tumors, similar to photodynamic therapy, but does not require oxygen or irradiation to activate photosensitizers.

Engineering a staggered type-II Bi2WO6/WO3 heterojunction with improved photocatalytic activity in wastewater treatment

In recent years, the removal organic pollutants from wastewater by advanced oxidation processes, especially photocatalysis, has become a meaningful approach due to its eco-friendliness and low cost. Herein, staggered type-II Bi2WO6/WO3 heterojunction photocatalysts were prepared by a facile hydrothermal route and investigated by modern physicochemical methods (X-ray diffraction, scanning electron microscopy, low-temperature nitrogen adsorption-desorption, and diffuse reflectance spectroscopy). The optimized BWOW-5 photocatalyst exhibited a H2O2-assisted photocatalytic methylene blue removal efficiency of 94.1% (k = 0.01414 min-1) within 180 min under optimal reaction conditions, which is much higher than that of unmodified Bi2WO6 and WO3 due to efficient separation of the photogenerated charge carriers. The trapping experiments demonstrate that photogenerated hydroxyl radicals and holes plays a key role in the photodegradation reaction. Moreover, the optimized BWOW-5 heterojunction photocatalyst exhibited excellent activity in the H2O2-assisted degradation of other pollutants, namely phenol, isoniazid, levofloxacin, and dibenzothiophene with the removal rate of 63.1, 73.6, 95.0, and 72.4%, respectively. This investigation offers a design strategy for Bi2WO6-based multifunctional photocatalytic composites with improved activity for organic pollutant degradation.

Fe/Au galvanic nanocells to generate self-sustained Fenton reactions without additives at neutral pH

The generation of reactive oxygen species (ROS) via the Fenton reaction has received significant attention for widespread applications. This reaction can be triggered by zero-valent metal nanoparticles by converting externally added H2O2 into hydroxyl radicals (˙OH) in acidic media. To avoid the addition of external additives or energy supply, developing self-sustained catalytic systems enabling onsite production of H2O2 at a neutral pH is crucial. Here, we present novel galvanic nanocells (GNCs) based on metallic Fe/Au bilayers on arrays of nanoporous silica nanostructures for the generation of self-sustained Fenton reactions. These GNCs exploit the large electrochemical potential difference between the Fe and Au layers to enable direct H2O2 production and efficient release of Fe2+ in water at neutral pH, thereby triggering the Fenton reaction. Additionally, the GNCs promote Fe2+/Fe3+ circulation and minimize side reactions that passivate the iron surface to enhance their reactivity. The capability to directly trigger the Fenton reaction in water at pH 7 is demonstrated by the fast degradation and mineralization of organic pollutants, by using tiny amounts of catalyst. The self-generated H2O2 and its transformation into ˙OH in a neutral environment provide a promising route not only in environmental remediation but also to produce therapeutic ROS and address the limitations of Fenton catalytic nanostructures.

A Facile Strategy for the Preparation of N-Doped TiO2 with Oxygen Vacancy via the Annealing Treatment with Urea

Although titanium dioxide (TiO2) has a wide range of potential applications, the photocatalytic performance of TiO2 is limited by both its limited photoresponse range and fast recombination of the photogenerated charge carriers. In this work, the preparation of nitrogen (N)-doped TiO2 accompanied by the introduction of oxygen vacancy (Vo) has been achieved via a facile annealing treatment with urea as the N source. During the annealing treatment, the presence of urea not only realizes the N-doping of TiO2 but also creates Vo in N-doped TiO2 (N-TiO2), which is also suitable for commercial TiO2 (P25). Unexpectedly, the annealing treatment-induced decrease in the specific surface area of N-TiO2 is inhibited by the N-doping and, thus, more active sites are maintained. Therefore, both the N-doping and formation of Vo as well as the increased active sites contribute to the excellent photocatalytic performance of N-TiO2 under visible light irradiation. Our work offers a facile strategy for the preparation of N-TiO2 with Vo via the annealing treatment with urea.

The role of superoxide anion to Cr(VI) reduction by pine biochar

It has been reported that Cr(VI) can be reduced by biochar because of its redox activity. Considering the anionic form of Cr(VI), we hypothesize that the reduction in aqueous phase is significant. However, the contribution of different reactive oxygen species in the biochar-Cr(VI) reaction system has not been distinguished. Herein, we quantitatively identified Cr(VI) adsorption and reduction in biochar systems. The reduction content of Cr(VI) was 1.5 times higher in untreated conditions than in anaerobic conditions. The disappearance of·O2- under anaerobic conditions illustrated that·O2- may be involved in the reduction of Cr(VI). Quenching of·O2- resulted in a decrease of Cr(VI) reduction by 34%, while 1O2 was negligible, probably due to the stronger electron-donating capacity of·O2-. The degradation of nitrotetrazolium blue chloride (quenching agent of·O2-) confirmed that the reduction process of·O2- mainly occurred in the liquid-phase. Boehm titration and quantification of·O2- further elucidated the significant correlation (P < 0.05) between phenolic groups and the formation of·O2-, which implied that phenolic groups acted as the primary electron donors in generating·O2-. This study highlights the importance of the liquid-phase reduction process in removing Cr(VI), which provides theoretical support for biochar conversion of Cr(VI).

Targeting programmed cell death in inflammatory bowel disease through natural products: New insights from molecular mechanisms to targeted therapies

Inflammatory bowel disease (IBD) is an autoimmune disorder primarily characterized by intestinal inflammation and recurrent ulceration, leading to a compromised intestinal barrier and inflammatory infiltration. This disorder's pathogenesis is mainly attributed to extensive damage or death of intestinal epithelial cells, along with abnormal activation or impaired death regulation of immune cells and the release of various inflammatory factors, which contribute to the inflammatory environment in the intestines. Thus, maintaining intestinal homeostasis hinges on balancing the survival and functionality of various cell types. Programmed cell death (PCD) pathways, including apoptosis, pyroptosis, autophagy, ferroptosis, necroptosis, and neutrophil extracellular traps, are integral in the pathogenesis of IBD by mediating the death of intestinal epithelial and immune cells. Natural products derived from plants, fruits, and vegetables have shown potential in regulating PCD, offering preventive and therapeutic avenues for IBD. This article reviews the role of natural products in IBD treatment by focusing on targeting PCD pathways, opening new avenues for clinical IBD management.

A ROS storm generating nanocomposite for enhanced chemodynamic therapy through H2O2 self-supply, GSH depletion and calcium overload

Catalytic generation of toxic hydroxyl radicals (˙OH) from hydrogen peroxide (H2O2) is an effective strategy for tumor treatment in chemodynamic therapy (CDT). However, the intrinsic features of the microenvironment in solid tumors, characterized by limited H2O2 and overexpressed glutathione (GSH), severely impede the accumulation of intracellular ˙OH, posing significant challenges. To circumvent these critical issues, in this work, a CaO2-based multifunctional nanocomposite with a surface coating of Cu2+ and L-buthionine sulfoximine (BSO) (named CaO2@Cu-BSO) is designed for enhanced CDT. Taking advantage of the weakly acidic environment of the tumor, the nanocomposite gradually disintegrates, and the exposed CaO2 nanoparticles subsequently decompose to produce H2O2, alleviating the insufficient supply of endogenous H2O2 in the tumor microenvironment (TME). Furthermore, Cu2+ detached from the surface of CaO2 is reduced by H2O2 and GSH to Cu+ and ROS. Then, Cu+ catalyzes H2O2 to generate highly cytotoxic ˙OH and Cu2+, forming a cyclic catalysis effect for effective CDT. Meanwhile, GSH is depleted by Cu2+ ions to eliminate possible ˙OH scavenging. In addition, the decomposition of CaO2 by TME releases a large amount of free Ca2+, resulting in the accumulation and overload of Ca2+ and mitochondrial damage in tumor cells, further improving CDT efficacy and accelerating tumor apoptosis. Besides, BSO, a molecular inhibitor, decreases GSH production by blocking γ-glutamyl cysteine synthetase. Together, this strategy allows for enhanced CDT efficiency via a ROS storm generation strategy in tumor therapy. The experimental results confirm and demonstrate the satisfactory tumor inhibition effect both in vitro and in vivo.

Enhanced photocatalytic efficiency of porous ZnO coral-like nanoplates for organic dye degradation

ZnO nanomaterials have been extensively used as photocatalysts for the removal of pollutants in aqueous environments. This study explores the enhanced photocatalytic performance of porous ZnO coral-like nanoplates synthesized via a one-pot wet-chemical method and subsequent annealing treatment. Characterization through scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, photoluminescence (PL) spectroscopy, and Brunauer-Emmett-Teller (BET) measurements confirmed the nanoplates' porous structure, single-crystal structure, 100 nm thickness, and 80 nm pore size. These unique structural characteristics of the ZnO coral-like nanoplates enabled effective photodegradation of the organic dye rhodamine B (RhB) under visible light irradiation. Under simulated sunlight, the ZnO photocatalyst exhibited exceptional performance, achieving a 97.3% removal rate of RhB after 210 minutes of irradiation. The prepared ZnO photocatalyst also showed remarkable photostability and regeneration capability for RhB photodegradation with a decreased efficiency of less than 15% after eight testing cycles. The potential mechanism of the ZnO photocatalyst toward RhB degradation was also studied and is discussed in detail.

Defect-rich sonosensitizers based on CeO2 with Schottky heterojunctions for boosting sonodynamic/chemodynamic synergistic therapy

Sonodynamic therapy (SDT) has been recognized as a promising treatment for cancer due to its advantages of superior specificity, non-invasiveness, and deep tissue penetration. However, the antitumor effect of SDT remains restricted by the limited generation of reactive oxygen species (ROS) due to the lack of highly efficient sonosensitizers. In this work, we developed the novel sonosensitizer Pt/CeO2-xSx by constructing oxygen defects through S doping and Pt loading in situ. Large amounts of oxygen defects have been obtained by S doping, endowing Pt/CeO2-xSx with the ability to suppress electron-hole recombination, further promoting ROS production. Moreover, the introduction of Pt nanoparticles can not only produce oxygen in situ for relieving hypoxia but also form a Schottky heterojunction with CeO2-xSx for further inhibiting electron-hole recombination. In addition, Pt/CeO2-xSx could effectively deplete overexpressed glutathione (GSH) via redox reactions, amplifying oxidative stress in the tumor microenvironment (TME). Combined with the excellent POD-mimetic activity, Pt/CeO2-xSx can achieve highly efficient synergistic therapy of SDT and chemodynamic therapy (CDT). All these findings demonstrated that Pt/CeO2-xSx has great potential for cancer therapy, and this work provides a promising direction for designing and constructing efficient sonosensitizers.

Enhanced photocatalytic and electrochemical performance of hydrothermally prepared NiO-doped Co nanocomposites

In this study, we synthesize nanostructured nickel oxide (NiO) and doped cobalt (Co) by combining nickel(II) chloride hexahydrate (NiCl2.6H2O) and sodium hydroxide (NaOH) as initial substances. We analyzed the characteristics of the product nanostructures, including their structure, optical properties, and magnetic properties, using various techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet absorption spectroscopy (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, and vibrating sample magnetometers (VSM). The NiO nanoparticles doped with Co showed photocatalytic activity in degrading methylene blue (MB) dye in aqueous solutions. We calculated the degradation efficiencies by analyzing the UV-Vis absorption spectra at the dye's absorption wavelength of 664 nm. It was observed that the NiO-doped Co nanoparticles facilitated enhanced recombination and migration of active elements, which led to more effective degradation of organic dyes during photocatalysis. We also assessed the electrochemical properties of the materials using cyclic voltammetry (CV) and impedance spectroscopy in a 1 mol% NaOH solution. The NiO-modified electrode exhibited poor voltammogram performance due to insufficient contact between nanoparticles and the electrolyte solution. In contrast, the uncapped NiO's oxidation and reduction cyclic voltammograms displayed redox peaks at 0.36 and 0.30 V, respectively.

Surface-enhanced Raman scattering spectroscopy monitoring and degradation of organic pollutants using a novel nanowire

A multifunctional Ag/AlOOH nanowires (ANW) composite substrate was constructed, which not only accomplishes highly sensitive detection of organic dye molecules, but also has excellent performance in the degradation of pollutants. The ANW in the Ag/ANW substrate possesses a high aspect ratio, which extends the distribution area of Ag and enables a large number of hot spots on the active substrate. Additionally, due to the abundant OH groups on the ANW, there is an increased number of anchor sites for adsorbed metal ions in the Ag/ANW compound, thus contributing to the enhancement and degradation of molecules. Moreover, the constructed multifunctional Ag/ANW nanocomplexes also show great promise for practical applications, providing a reference for the detection and degradation of contaminants.

Preparation of Novel Layered High Entropy Bismuth-Based Materials and their Photocatalytic Degradation Mechanism

We prepared BiOCl, BiO(ClBr), BiO(ClBrI), and BiO[ClBrI(CO3)0.5] materials using a simple coprecipitation method. It was found that adjusting the number of anions in the anion layer was conducive to adjusting the band structure of BiOX and could effectively promote the migration and separation of photogenerated carriers, thus improving the photocatalytic activity. We first selected methyl orange (MO) as the study pollutant and compared it with BiOCl, BiO(ClBr), and BiO(ClBrI). The first-order kinetic constants of MO degradation by BiO[ClBrI(CO3)0.5] increased by 90.3, 33.9, and 3.1 times, respectively. The photocatalytic degradation rate of methylene blue by BiO[ClBrI(CO3)0.5] was 89.5%, indicating the excellent photocatalytic performance of BiO[ClBrI(CO3)0.5]. The stability of BiO[ClBrI(CO3)0.5] was demonstrated through cyclic experiments and XRD analysis before and after the reaction. The photocatalytic degradation of MO by BiO[ClBrI(CO3)0.5] showed that h+ and 1O2 were the main active oxidizing species and •O2- was the secondary active substance. Overall, our work provides new ideas for the synthesis and degradation of organic pollutants by using two-dimensional anionic high-entropy materials.

Synergistic integration of ZrO2-enriched reduced graphene oxide-based nanostructures for advanced photodegradation of tetracycline hydrochloride

The escalating demand for the antibiotic drug tetracycline hydrochloride (TCH) contributes to an increased release of its residues into land and water bodies, which poses risks to both aquatic life and human health. Therefore, it is precedence to effectively degrade TCH residues to protect environment from their long-term impacts. In this aspect, the present study entails the synthesis of zirconia (ZrO2) nanostructures and focuses on the enhancement in the catalytic performance of ZrO2 nanostructures by employing reduced graphene oxide (RGO) as a solid support to synthesize ZrO2-enriched RGO-based photocatalysts (ZrO2-RGO) for the degradation of TCH. The study delves into comprehensive spectroscopic and microscopic investigations and their photodegradation assessments. Powder XRD and HR-TEM studies depicted the phase crystallinity and also displayed uniform distribution of ZrO2 nanostructures with spherical morphology within ZrO2-RGO. This corresponds to high surface-to-volume ratios, providing a substantial number of active sites for light absorption and generation of e--h+ pairs. Moreover, the heterojunctions created between RGO and ZrO2 nanostructures promoted the interspecies electron transfer which prolonged the recombination time of e- and h+ than pure ZrO2 nanostructures, accounted for enhanced degradation of TCH using ZrO2-RGO. The photocatalytic activity of as-synthesized materials were examined under visible and UV light irradiation. The degradation efficiency of ~ 73.82% was achieved using ZrO2-RGO-based photocatalyst with rate constant k = 0.007023 min-1 under visible-light illumination. Moreover, under UV-light, the degradation rate was explicated to be k = 0.01017 min-1 with ~ 85.56% degradation of TCH antibiotics within 180 mins. Hence, the synthesized ZrO2-enriched RGO-based photocatalysts represents a promising potential for the effective degradation of pharmaceutical compounds, particularly TCH under visible and UV-light irradiation.

Advances in Research on the Activity Evaluation, Mechanism and Structure-Activity Relationships of Natural Antioxidant Peptides

Antioxidant peptides are a class of biologically active peptides with low molecular weights and stable antioxidant properties that are isolated from proteins. In this review, the progress in research on the activity evaluation, action mechanism, and structure-activity relationships of natural antioxidant peptides are summarized. The methods used to evaluate antioxidant activity are mainly classified into three categories: in vitro chemical, in vitro cellular, and in vivo animal methods. Also, the biological effects produced by these three methods are listed: the scavenging of free radicals, chelation of metal ions, inhibition of lipid peroxidation, inhibition of oxidative enzyme activities, and activation of antioxidant enzymes and non-enzymatic systems. The antioxidant effects of natural peptides primarily consist of the regulation of redox signaling pathways, which includes activation of the Nrf2 pathway and the inhibition of the NF-κB pathway. The structure-activity relationships of the antioxidant peptides are investigated, including the effects of peptide molecular weight, amino acid composition and sequence, and secondary structure on antioxidant activity. In addition, four computer-assisted methods (molecular docking, molecular dynamics simulation, quantum chemical calculations, and the determination of quantitative structure-activity relationships) for analyzing the structure-activity effects of natural peptides are summarized. Thus, this review lays a theoretical foundation for the development of new antioxidants, nutraceuticals, and cosmetics.

Strategic Insertion of Heavy Atom to Tailor TADF OLED Material for the Development of Type I Photosensitizing Catalytic Red Emissive Assemblies

The work presented in the manuscript describes a simple strategy for transforming thermally activated delayed fluorescent organic light-emitting diodes (TADF OLEDs) compound 10-(dibenzo[a,c]phenazin-11-yl)-10H-phenoxazine (DPZ-PXZ) into type I photosensitizer 10-(dibenzo[a,c]phenazin-11-yl)-10H-phenothiazine (DPZ-PHZ) by strategically introducing sulfur atom in the photosensitizing core. The synthesized compound DPZ-PHZ exhibits aggregation-induced enhancement (AIE) and through-space charge transfer (TSCT) characteristics and generates red emissive assemblies in mixed aqueous media. The original compound DPZ-PXZ exhibits well-separated HOMO and LUMO levels and is reported to have highly efficient reverse intersystem crossing (RISC). In comparison, the incorporation of sulfur atom in the phenothiazine donor regulates the electronic communication between donor and acceptor units and promotes the intersystem crossing (ISC) in DPZ-PHZ molecules. Interestingly, compound DPZ-PHZ exhibits rapid activation of aerial oxygen for instant generation of superoxide radical anion. Backed by excellent type I photosensitizing activity, DPZ-PHZ assemblies have high catalytic potential for the synthesis of benzimidazoles, benzothiazoles and quinazolines derivatives under mild reaction conditions. The work presented in the manuscript provides an insight into the combination of heavy atom approach and TSCT for achieving adequate electronic communication between donor and acceptor units, balanced RISC/ISC, and stabilized-charge separated state for the development of efficient type I photosensitizing assemblies.

Role of NLRP3 in Parkinson's disease: Specific activation especially in dopaminergic neurons

Parkinson's disease (PD) is a neurodegenerative disorder with motor symptoms like bradykinesia, tremors, and balance issues. The pathology is recognized by progressively degenerative nigrostriatal dopaminergic neurons (DANs) loss. Its exact pathogenesis is unclear. Numerous studies have shown that nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) contributes to the pathogenesis of PD. Previous studies have demonstrated that the over-activation of NLRP3 inflammasome in microglia indirectly leads to the loss of DANs, which can worsen PD. In recent years, autopsy analyses of PD patients and studies in PD models have revealed upregulation of NLRP3 expression within DANs and demonstrated that activation of NLRP3 inflammasome in neurons is sufficient to drive neuronal loss, whereas microglial activation occurs after neuronal death, and that inhibition of intraneuronal NLRP3 inflammasome prevents degeneration of DANs. In this review, we provide research evidence related to NLRP3 inflammasome in DANs in PD as well as focus on possible mechanisms of NLRP3 inflammasome activation in neurons, aiming to provide a new way of thinking about the pathogenesis and prevention of PD.

Fenton-like system of UV/Glucose-oxidase@Kaolin coupled with organic green rust: UV-enhanced enzyme activity and the mechanism of UV synergistic degradation of photosensitive pollutants

This study introduces the UV/glucose-oxidase@Kaolin (GOD@Kaolin) coupled organic green rust (OGR) system (UV/OGR/GOD@Kaolin) to investigate the promotion of glucose oxidase activity by UV light and its synergistic degradation mechanism for photosensitive pollutants, specifically targeting the efficient degradation of 4-chlorophenol (4-CP). The enzyme system demonstrates its ability to overcome drawbacks associated with traditional Fenton systems, including a narrow pH range and high localized concentration of H2O2, by gradually releasing hydrogen peroxide in situ within a neutral environment. In the presence of UV radiation under specific conditions, enhanced enzyme activity is observed, resulting in increased efficiency in pollutant removal. The gradual release of hydrogen peroxide plays a crucial role in preventing unwanted reactions among active substances. These unique features facilitate the generation of highly reactive species, such as Fe(IV)O, •OH, and •O2-, tailored to efficiently target the organic components of interest. Additionally, the system establishes a positive iron cycle, ensuring a sustained reactive capability throughout the degradation process. The results highlight the UV/OGR/GOD@Kaolin system as an effective and environmentally friendly approach for the degradation of 4-CP, and the resilience of the enzyme extends the system's applicability to a broader range of scenarios.

Molecular surface-dependent light harvesting and photo charge separation in plant-derived carbon quantum dots for visible-light-driven OH radical generation for remediation of aromatic hydrocarbon pollutants and real wastewater

Despite the growing emphasis on eco-friendly nanomaterials as energy harvesters, scientists are actively searching for metal-free photocatalysts to be used in environmental remediation strategies. Developing renewable resource-based carbon quantum dots (CQDs) as the sole photocatalyst to harvest visible light for efficient pollutant degradation is crucial yet challenging, particularly for addressing the escalating issue of water deterioration. Moreover, the photocatalytic decomposition of H2O2 under visible light irradiation remains an arduous task. Based on this, we designed two types of CQDs, C-CQDs (carboxylic-rich) and A-CQDs (amine-rich) with distinct molecular surfaces. Owing to the higher amount of upward band bending induced by amine-rich molecular surface, A-CQDs efficiently harvest the visible light and prevent recombination kinetics resulting in prolonged lifetimes (25 ps), and augmented charge carrier density (35.7 × 1018) of photoexcited charge carriers. A-CQDs enabled rapid visible-light-driven photolysis of H2O2 (k = 0.058 min-1) and produced higher quantity of •OH radicals (0.158 μmol/sec) for the mineralization of petroleum waste, BETX (i.e. Benzene, Ethylbenzene, Toluene and Xylene) (k = 0.017-0.026 min-1) and real textile wastewater (k = 0.026 min-1). To assess comparative toxicities of both remediated and non-remediated real wastewater samples in a time and dose depended manner, Drosophila melanogaster was used as a model organism. The findings unequivocally demonstrate the potential of remediated wastewater for watering urban forestry.

Breaking the pH Limitation of Nanozymes: Mechanisms, Methods, and Applications

Although nanozymes have drawn great attention over the past decade, the activities of peroxidase-like, oxidase-like, and catalase-like nanozymes are often pH dependent with elusive mechanism, which largely restricts their application. Therefore, a systematical discussion on the pH-related catalytic mechanisms of nanozymes together with the methods to overcome this limitation is in need. In this review, various nanozymes exhibiting pH-dependent catalytic activities are collected and the root causes for their pH dependence are comprehensively analyzed. Subsequently, regulatory concepts including catalytic environment reconstruction and direct catalytic activity improvement to break this pH restriction are summarized. Moreover, applications of pH-independent nanozymes in sensing, disease therapy, and pollutant degradation are overviewed. Finally, current challenges and future opportunities on the development of pH-independent nanozymes are suggested. It is anticipated that this review will promote the further design of pH-independent nanozymes and broaden their application range with higher efficiency.

Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration

Photocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD-COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 μmol g-1 h-1 in O2 and air) than TBC-COF with hcb topology through the O2-O2⋅--H2O2, O2-O2⋅--O2 1-H2O2, and H2O-H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅- generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O2 1, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high-performance photocatalysts for H2O2 production by topological structure modulation.

Hydroxylation of the indium tin oxide electrode promoted by surface bubbles

Adherent bubbles at electrodes are generally treated as reaction penalties. Herein, in situ hydroxylation of indium tin oxide surfaces can be easily achieved by applying a constant potential of +1.0 V in the presence of bubbles. Its successful hydroxylation is further demonstrated by preparing a ferrocene-terminated film, which is confirmed by cyclic voltammetry and X-ray photoelectron spectroscopy.

Recent Developments in Porphyrin-Based Metal-Organic Framework Materials for Water Remediation under Visible-Light Irradiation

Access to clean drinking water is a basic requirement, and eliminating pollutants from wastewater is important for saving water ecosystems. The porous structure and surface characteristics of metal-organic frameworks (MOFs) can function as a perfect scaffold for removing toxic compounds from wastewater. Porphyrins are promising building blocks for constructing MOFs. Porphyrin-based metal-organic frameworks (P-MOFs) have been fabricated using porphyrin ligands, metal clusters, or ions. These materials can harvest light from a wide region of the solar spectrum, and their framework morphology and physicochemical properties can be controlled by changing their peripheral subunits or metal ions. These porous crystalline materials have generated interest because of their distinctive characteristics, including large permanent porosity, interesting surface morphology, broad conformational diversity, high photostability, and semiconducting nature. This article discusses the recent progress and usefulness of P-MOFs. The fabrication procedures of P-MOFs are discussed, followed by the adsorptive and photocatalytic removal of contaminants from wastewater. The relationships between the geometries of P-MOFs and their light-harvesting and charge-transfer mechanisms for the photocatalytic degradation of pollutants are highlighted. Finally, some future perspectives and obstacles in the photodegradation usage of P-MOFs are discussed, along with feasible research directions to standardize efficient photocatalysts for improved photodegradation for water treatment.

Enhanced Generation of Reactive Oxygen Species via Piezoelectrics based on p-n Heterojunctions with Built-In Electric Field

Tuning the charge transfer processes through a built-in electric field is an effective way to accelerate the dynamics of electro- and photocatalytic reactions. However, the coupling of the built-in electric field of p-n heterojunctions and the microstrain-induced polarization on the impact of piezocatalysis has not been fully explored. Herein, we demonstrate the role of the built-in electric field of p-type BiOI/n-type BiVO4 heterojunctions in enhancing their piezocatalytic behaviors. The highly crystalline p-n heterojunction is synthesized by using a coprecipitation method under ambient aqueous conditions. Under ultrasonic irradiation in water exposed to air, the p-n heterojunctions exhibit significantly higher production rates of reactive species (·OH, ·O2-, and 1O2) as compared to isolated BiVO4 and BiOI. Also, the piezocatalytic rate of H2O2 production with the BiOI/BiVO4 heterojunction reaches 480 μmol g-1 h-1, which is 1.6- and 12-fold higher than those of BiVO4 and BiOI, respectively. Furthermore, the p-n heterojunction maintains a highly stable H2O2 production rate under ultrasonic irradiation for up to 5 h. The results from the experiments and equation-driven simulations of the strain and piezoelectric potential distributions indicate that the piezocatalytic reactivity of the p-n heterojunction resulted from the polarization intensity induced by periodic ultrasound, which is enhanced by the built-in electric field of the p-n heterojunctions. This study provides new insights into the design of piezocatalysts and opens up new prospects for applications in medicine, environmental remediation, and sonochemical sensors.

Tri-mode Responses to Reactive Oxygen Species In Vivo by Chiral Vanadium-Based Nanoparticles

Reactive oxygen species (ROS) are closely associated with the redox balance of the physiological environment, and monitoring ROS can aid in the early diagnosis of many diseases, including cancer. In this study, chiral vanadium trioxide/vanadium nitride (V2O3/VN) nanoparticles (NPs) modified with an organic dye (cyanine 3 [Cy3]) were prepared for ROS sensing. Chiral V2O3/VN NPs were prepared with the "ligand-induced chirality" strategy and showed a g-factor of up to 0.12 at a wavelength of 512 nm. To the best of our knowledge, this g-factor is the highest value of all chiral ceramic nanomaterials. The very high g-factor of the nanoprobe confers very high sensitivity, because the higher g-factor, the higher sensitivity. In the presence of ROS, V3+ in the chiral V2O3/VN nanoprobe undergoes a redox reaction to form V2O5, reducing the circular dichroism and absorbance signals, whereas the fluorescence signal of Cy3 is restored. With this nanoprobe, the limits of detection for the circular dichroic and fluorescence signals in living cells are 0.0045 nmol/106 and 0.018 nmol/106 cells, respectively. This chiral nanoprobe can also monitor ROS levels in vivo by fluorescence. This strategy provides an innovative approach to the detection of ROS and is expected to promote the wider application of chiral nanomaterials for biosensing.

Increasing the Accessibility of Internal Catalytic Sites in Covalent Organic Frameworks by Introducing a Bicontinuous Mesostructure

Introducing continuous mesochannels into covalent organic frameworks (COFs) to increase the accessibility of their inner active sites has remained a major challenge. Here, we report the synthesis of COFs with an ordered bicontinuous mesostructure, via a block copolymer self-assembly-guided nanocasting strategy. Three different mesostructured COFs are synthesized, including two covalent triazine frameworks and one vinylene-linked COF. The new materials are endowed with a hierarchical meso/microporous architecture, in which the mesochannels exhibit an ordered shifted double diamond (SDD) topology. The hierarchically porous structure can enable efficient hole-electron separation and smooth mass transport to the deep internal of the COFs and consequently high accessibility of their active catalytic sites. Benefiting from this hierarchical structure, these COFs exhibit excellent performance in visible-light-driven catalytic NO removal with a high conversion percentage of up to 51.4 %, placing them one of the top reported NO-elimination photocatalysts. This study represents the first case of introducing a bicontinuous structure into COFs, which opens a new avenue for the synthesis of hierarchically porous COFs and for increasing the utilization degree of their internal active sites.

Delocalization Engineering of Heme-Mimetic Artificial Enzymes for Augmented Reactive Oxygen Catalysis

Developing artificial enzymes based on organic molecules or polymers for reactive oxygen species (ROS)-related catalysis has broad applicability. Herein, inspired by porphyrin-based heme mimics, we report the synthesis of polyphthalocyanine-based conjugated polymers (Fe-PPc-AE) as a new porphyrin-evolving structure to serve as efficient and versatile artificial enzymes for augmented reactive oxygen catalysis. Owing to the structural advantages, such as enhanced π-conjugation networks and π-electron delocalization, promoted electron transfer, and unique Fe-N coordination centers, Fe-PPc-AE showed more efficient ROS-production activity in terms of Vmax and turnover numbers as compared with porphyrin-based conjugated polymers (Fe-PPor-AE), which also surpassed reported state-of-the-art artificial enzymes in their activity. More interestingly, by changing the reaction medium and substrates, Fe-PPc-AE also revealed significantly improved activity and environmental adaptivity in many other ROS-related biocatalytic processes, validating the potential of Fe-PPc-AE to replace conventional (poly)porphyrin-based heme mimics for ROS-related catalysis, biosensors, or biotherapeutics. It is suggested that this study will offer essential guidance for designing artificial enzymes based on organic molecules or polymers.

Enhanced Photocatalytic Oxygen Evolution Using Copper-Coordinated Perylene Diimide Nanorod Assemblies

A crystalline supramolecular photocatalyst is prepared through metal-induced self-assembly of perylene diimide with imidazole groups at the imide position (PDI-Hm). Exploiting the metal-coordination ability of imidazole, a crystalline assembly of copper-coordinated PDI-Hm (CuPDI-Hm) in a nanorod shape is prepared which displays an outstanding photocatalytic oxygen evolution rate of 25,900 μmol g-1 h-1 without additional co-catalysts. The imidazole-copper coordination, along with π-π stacking of PDI frameworks, guides the arrangement of PDI-Hm molecules to form highly crystalline assemblies. The coordination of copper also modulates the size of the CuPDI-Hm supramolecular assembly by regulating the nucleation and growth processes. Furthermore, the imidazole-copper coordination constructs the electric field within the PDI-Hm assembly, hindering the recombination of photo-induced charges to enhance the photoelectric/photocatalytic activity when compared to Cu-free PDI-Hm assemblies. Small CuPDI-Hm assembly exhibits higher photocatalytic activity due to their larger surface area and reduced light scattering. Together, the Cu-imidazole coordination presents a facile way for fabricating size-controlled crystalline PDI assemblies with built-in electric field enhancing photoelectric and photocatalytic activities substantially.