Semiconductor photocatalysts: A critical review highlighting the various strategies to boost the photocatalytic performances for diverse applications

Electron donor-acceptor metal-organic frameworks for efficient photocatalytic reduction and oxidation

It is a great challenge to obtain a broad-spectrum light response and high redox capability in photocatalysis. Unlike the traditional process of expanding the light spectrum of a photocatalyst often leads to a decrease in oxidation or reduction potential, here we proposed a mixed-ligand strategy to improve the light response and photocatalytic redox performances simultaneously. Tetrad (4-carboxyphenyl) porphyrin (TCPP, electron donor) and N, N'-bis (5-diphenylphthalic acid)-naphthlimide (NDI, electron acceptor) were coordinated with Zr (IV) clusters to produce electron donor-acceptor (D-A) metal-organic frameworks (ML-MOFs). As photocatalysts, the ML-MOFs exhibited higher photocatalytic efficiency in the generation of nicotinamide adenine dinucleotide phosphate (NADH) in the absence of any noble metals. Refractory antibiotic tetracycline hydrochloride (TCH) was almost completely degraded within 30 min with an amazing kinetic constant of 0.08229 min-1, far exceeding that of the single-ligand MOFs and other noble-metal-free photocatalysts. The experimental and theoretical evidence indicated the D-A structure in ML-MOFs achieved larger dipole moments and enlarged built-in electric fields, which greatly improved the charge separation and transfer efficiency, conferring them with boosting photocatalytic oxidation and reduction performances. This research presents a new stratagem for the preparation of advanced photocatalysts with both photocatalytic oxidation and reduction ability and makes a significant step towards energy conversion and environmental governance via photocatalysis.

Engineering a dual Z-scheme copper oxide/boron carbon nitride/MXene heterojunction with tailored band alignment for high-efficiency photocatalytic degradation of refractory organic pollutants

The accumulation of persistent environmental pollutants presents significant risks to ecosystems and human health, requiring immediate removal and effective control as a pressing global concern. Herein, we report the design and fabrication of graphitic carbon nitride (g-C3N4) based dual Z-Scheme heterojunction for effective photocatalytic degradation of various refractory pollutants in wastewater. Firstly, we synthesized boron-doped g-C3N4 via the direct calcination of melamine along with boric acid, and then coupled with Copper Oxide (CuO) and MXene via the wet-chemical method to fabricate dual Z-scheme CuO/BCN/MXene composite. The physicochemical features of the as-prepared CuO/BCN/MXene composite and reference samples were investigated via various characterization techniques. The photocatalytic degradation performance and the kinetics study for malachite green was evaluated using the as-fabricated dual Z-scheme composite and the coupling components. The CuO/BCN/MXene composite revealed exceptional photocatalytic performance by achieving 98.3 % degradation for malachite green, which is remarkably higher than the reference samples. The enhanced performance was attributed to the band gap narrowing, extended light absorption, and improved charge carrier separation. This study will provide new insights into the design and fabrication of functional nanomaterials for efficient photocatalytic degradation of pollutants and other applications.

In-situ preparation of highly dispersed Fe doping C3N5 induced by inorganic iron salts with effective activation of PMS for photocatalytic degradation of chlortetracycline

A highly dispersed Fe in situ doped C3N5 (Fe-C3N5) photocatalyst utilizing inorganic iron salt was successfully prepared, which was applied in photocatalytic synergistic advanced oxidative degradation of chlortetracycline (CTC) under the activation with persulfate. BET measurements revealed that uniform Fe doping increases the specific surface area, thus enhancing the reactive active sites. Photoelectric tests indicate that Fe doping optimizes the energy band structure of C3N5, thereby enhancing electron transfer, and the photogenerated electrons facilitate the Fe2+/Fe3+ redox cycle, which is beneficial for the sustained and efficient activation of persulfates. The Fe-C3N5(50 %)/PMS/Vis system achieved over 95 % degradation of CTC within 2 h, after four cycles, the Fe-C3N5(50 %) still exhibits good reusability and stability. Free radical quenching experiments coupled with EPR spectroscopy identified 1O2, h+, and ·O2- as the dominant reactive species driving the degradation of CTC, elucidating the potential degradation mechanisms. Based on LC-MS measurements and utilizing the TEST toxicity assessment software, it has been determined that CTC ultimately decomposes into non-toxic small molecules, such as CO2 and H2O. Furthermore, a hydroponic germination experiment using mung beans was conducted to demonstrate that Fe-C3N5(50 %) does not exhibit toxic effects on plant growth. Importantly, this study offers novel insights into the green synthesis of highly dispersed Fe doping C3N5 photocatalytic for the efficient degradation of CTC.

Hydrothermal Synthesis of Nanocomposites Combining Tungsten Trioxide and Zinc Oxide Nanosheet Arrays for Improved Photocatalytic Degradation of Organic Dye

Both tungsten trioxide (WO3) nanosheet arrays and tungsten trioxide/zinc oxide (WO3/ZnO) nanocomposites were grown on fluorine-doped tin oxide (FTO) coated glass slides using a hydrothermal method to develop a visible-light-driven photocatalyst with easy reusability. Field emission scanning electron microscopy (FE-SEM) observations confirmed the formation of irregular oxide nanosheet arrays on the FTO surfaces. X-ray diffraction (XRD) analysis revealed the presence of hexagonal WO3 and wurtzite ZnO crystal phases. UV-Vis diffuse reflectance spectroscopy showed that integrating ZnO nanostructures with WO3 nanosheets resulted in a blue shift of the absorption edge and a reduced absorption capacity in the visible-light region. Photoluminescence (PL) spectra indicated that the WO 0.5/ZnO 2.0 sample exhibited the lowest electron-hole recombination rate among the WO3/ZnO nanocomposite sample. Photocatalytic degradation tests demonstrated that all WO3/ZnO nanocomposite samples had higher photodegradation rates for a 10 ppm methylene blue (MB) aqueous solution under visible-light irradiation compared to pristine WO3 nanosheet arrays. Among them, the WO 0.5/ZnO 2.0 sample showed the highest photocatalytic efficiency. Furthermore, it exhibited excellent recyclability and high photodegradation stability over three cycles.

Surfactant-tuned vanadium pentoxide for enhanced photocatalytic degradation of organic dyes: nanosheet vs. microflower morphologies

This study explores the impact of surfactants on the morphology and photocatalytic performance of V2O5 materials synthesized via a hydrothermal method, followed by calcination. Two surfactants, Pluronic P123 and cetrimonium bromide (CTAB), were used, leading to the formation of V2O5 nanosheets (V2O5-P123) and V2O5 microflowers (V2O5-CTAB), each exhibiting distinct structural characteristics and photocatalytic efficiencies. The prepared nanosheets are of sizes ranging from a few micrometers and thickness of approximately 50-60, and the flower-like structures have an average diameter of approximately 5 micrometers. The photocatalytic degradation of Methylene Blue (MB) and Rhodamine B (RhB) dyes were evaluated under simulated sunlight. The V2O5-P123 nanosheets showed superior performance, achieving 96.72% MB degradation in 150 minutes, with a degradation rate constant of 0.92 min-1, compared to 90.02% for V2O5-CTAB microflowers (0.51 min-1). This enhanced performance was attributed to the larger surface area, higher porosity, and optimized structure of the nanosheets, which promoted better dye adsorption and interaction with reactants. In contrast, the degradation of RhB was lower for both structures, with the V2O5-P123 nanosheets achieving only 18% degradation (rate constant: 0.0014 min-1) and the V2O5-CTAB microflowers 46% (rate constant: 0.0071 min-1). This highlights the challenge of degrading RhB due to its complex molecular structure and higher chemical stability, limiting effective interaction with the catalyst surface. The study emphasizes the significant influence of surfactants on the morphology and photocatalytic performance of V2O5 materials, with V2O5 nanosheets showing promising potential for environmental remediation, particularly in the degradation of organic pollutants like MB. The findings also suggest that optimizing the photocatalyst design could enhance the degradation of more chemically stable pollutants, thereby expanding the scope of applications for clean energy production and environmental protection.

Morinda citrifolia fruit extract-mediated synthesis of ZnO and Ag/ZnO nanoparticles for photocatalytic degradation of tetracycline

Bio-mediated synthesis of zinc oxide (ZnO) nanoparticles using plant extracts has been paid attention but still remains several challenges, e.g., alkaline addition during biosynthesis and photocatalytic effectiveness. Here, ZnO and silver (Ag)-doped ZnO at different ratios (0.5%, 1%, 3%, 5%, and 7%) were synthesized by an alkali-free method using Morinda citrifolia fruit extract. These materials were used as efficient photocatalysts for the tetracycline hydrochloride degradation. The impact of factors such as synthesis condition, Ag doping, pH, concentration, catalyst dosage, coexisting ions, and different light sources on the photocatalytic performance of green ZnO and Ag/ZnO nanoparticles was studied. The Ag-1%/ZnO composite exhibited the highest photocatalytic activity. The chief mechanisms involved in the photocatalytic process of Ag-doped ZnO nanoparticles were insightfully clarified through electrochemical and scavenging analyses. Active species including •O2-, h+, and e- played a vital role in the tetracycline hydrochloride degradation mechanism. Moreover, Ag-1%/ZnO represented four cycles with a minor decrease in degradation efficiency from 84% to 79% from the 1st to the 4th cycle. Morinda citrifolia fruit extract-mediated Ag/ZnO nanoparticles is suggested as an effective and recyclable photocatalyst in the tetracycline antibiotic treatment.

Suppression of charge recombination using microfibrillated cellulose in carboxymethyl cellulose coatings containing ZnO nanorods and BiOCl during photoelectrocatalysis

Photocatalysts have been extensively developed as they can degrade various water pollutants under light irradiation without chemical consumption. However, photocatalyst reusability and uniform light distribution still limit the scaling up of photocatalytic processes. This study investigated the photoelectrocatalytic (PEC) system removal of dye using zinc oxide nanorods (ZnONRs) and bismuth oxychloride (BiOCl) immobilized in the carboxymethyl cellulose (CMC) coating containing microfibrillated cellulose (MFC). The photocatalytic properties were significantly enhanced by the presence of MFC with 3D fibrous network that could disperse the photocatalyst, reduce recombination, and promote charge migration. The MFC/ZnONRs/BiOCl/CMC coating worked as a photoanode, which removed 78 % of methylene blue (MB) dye within 60 min under UV light irradiation and a low voltage of 2.5 V.

Scalable single-step deposition of recyclable TiO2@Au monolayer coatings for enhanced visible-light photocatalysis of methylene blue dye

Titanium dioxide@gold (TiO2@Au) nanocomposite monolayers with enhanced visible-light photocatalysis were synthesized via an air-water interfacial self-assembly and pyrolysis strategy. This method simultaneously embeds Au nanoparticles (5-20 nm) within TiO2 and reduces the bandgap from 3.02 eV to 2.66 eV via interfacial charge redistribution. In a 200 ml aqueous reaction system, the TiO2@Au monolayers demonstrated a visible-light-driven methylene blue degradation rate of 0.0054 min-1-3.6-fold higher than pure TiO2, attributed to Au's localized surface plasmon resonance (LSPR) enhancing visible-light absorption and interfacial electron transfer. The system maintained 99.2% activity retention over five cycles, showcasing unprecedented stability in large-volume wastewater treatment scenarios. This method leverages self-limiting assembly at the air-water interface to orchestrate the molecular packing of organometallic precursor films, which upon pyrolysis yield centimeter-scale nanocomposite monolayers. The developed methodology provides a practical pathway for industrial photocatalytic wastewater purification.

N, O-Doped surface modulation of ZnIn2S4 with high hydrophilicity for enhanced photocatalytic hydrogen evolution

Heteroatom doping is a promising strategy for optimizing the photocatalytic activity of semiconductors. However, relying solely on single-element doping often poses challenges in modulating the capabilities of semiconductors. Herein, we adopt a strategy of simultaneously modifying ZnIn2S4 with the double non-metallic elements nitrogen (N) and oxygen (O) to form (N, O)-ZnIn2S4. Interestingly, (N, O)-ZnIn2S4 exhibits significantly higher hydrophilicity and specific surface area compared to pristine ZnIn2S4. The contact angle decreases from 24° to 21°, while the specific surface area increases from 56 m2/g to 75 m2/g. The hydrogen production rate of (N, O)-ZnIn2S4 reaches 400 μmol/h/g, which is 2.52 times higher than that of pristine ZnIn2S4. Photoelectrochemical characterization reveals that (N, O)-ZnIn2S4 has a lower overpotential, higher photocurrent, lower resistance, reduced fluorescence intensity, and shorter fluorescence lifetime. Additionally, co-catalyst loading boosts the hydrogen production activity of ZnCo2S4/(N, O)-ZnIn2S4 from 548 μmol/h/g to 810 μmol/h/g, compared to ZnCo2S4/ZnIn2S4. This study presents a dual non-metallic modification strategy to enhance semiconductor properties, achieving superior performance in photocatalytic hydrogen production.

Photothermal-assisted S-scheme heterojunction of Cu3SnS4/Mn0.3Cd0.7S for enhanced photocatalytic hydrogen production

Photocatalytic hydrogen evolution is regarded as an economically viable and environmentally benign strategy. However, the practical application of photocatalytic hydrogen production is constrained by the sluggish reaction kinetics and rapid recombination of photogenerated charge carriers. Herein, a Cu3SnS4/Mn0.3Cd0.7S (CTS/MCS) S-scheme photocatalyst with photothermal effect was synthesized via an ultrasound-assisted self-assembly method and applied for the first time to photocatalytic hydrogen evolution. The hydrogen production rate of CTS/MCS-5 reached 72.5 ± 0.8 mmol/h g-1, representing a 3.44-fold increase relative to Mn0.3Cd0.7S, and the apparent quantum yield of CTS/MCS-5 reached 17.5 % at 450 nm. The photothermal effect induced by Cu3SnS4 can elevate the local surface temperature of the catalyst, providing a portion of the energy required for the reaction, thereby reducing the reaction barrier and further promoting photocatalytic reactions. This research highlights the significance of the S-scheme heterojunction and the photothermal effect as an effective strategy to enhance photocatalytic activity, offering new insights for the development of photocatalytic hydrogen evolution technology.

Design, synthesis, and optimization of a novel ternary photocatalyst for degradation of cephalexin antibiotic in aqueous solutions

The widespread use of antibiotics in veterinary and medical applications has increased the possibility of water contamination, which causes adverse effects such as increased bacterial resistance in humans and other organisms. This study, investigates the efficient removal of cephalexin (CPX) using Fe doped TiO2-Bi2O3 nanocomposite, synthesized via the simple sol-gel method as a visible active photocatalyst. The weight fraction of Fe (3-7 wt%), and Bi2O3 (7-11 wt%) was optimized. The Fe-TiO2-Bi2O3 nanocomposite with a weight fraction of 3 and 11% for Fe and Bi2O3 has the best photocatalytic activity for Cephalexin degradation. The characteristics of photocatalyst with optimum composite (3 wt% of Fe and 11 wt% Bi2O3) were also investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), diffuse reflectance spectra (DRS) and FTIR. The DRS spectra approved that the adsorption wavelength of Fe-doped TiO2-Bi2O3 is in the visible light range. The influence of amount of catalyst (0.5-1.5 g/L), Cephalexin concentration (5-15 mg/L) and initial pH of the solution (3-9) in on CPX photodegradation was modeled and optimized using central composite design based on response surface methodology. Maximum cephalexin degradation Under visible light irradiation (50 W LED, 395-400 nm) was achieved about 74% at 5 mg/L of CPX, 1.5 g/L catalyst loading and pH of 9 in 240 min. Moreover, using a 15W UV lamp under the same conditions increased the degradation efficiency to 96% at 120 min. Considering the high potential of Fe-TiO2/Bi2O3 nanocomposite in removing Cephalexin antibiotics, it can be considered a suitable candidate for removing antibiotics from contaminated water sources.

Study on Mechanical Properties, Optical Properties, Cytotoxicity of TiO2-HAP Nanoparticles-Modified PMMA and Photodynamically Assisted Antibacterial Activity Against Candida Albicans in Vitro

Statement of Problem

The high recurrence rate of denture stomatitis may be related to the strong resistance of fungi. Therefore, the method of providing biomaterials with antifungal properties is an attractive solution for improving microbial control.

Purpose

Against the drug resistance of Candida albicans, this study aim to elucidate the photocatalytic antibacterial effect of TiO2-HAP nanocomposite-modified PMMA on Candida albicans through in vitro experiments, and to evaluate the potential impact of the mechanical properties, optical properties, cytotoxicity and contact angle of the modified PMMA, to provide a scientific basis for the development of denture base resins with minimum percentage of photocatalytic additives.

Methods

In this study, TiO2-HAP nanoparticles were mixed with self-polymerized PMMA in different mass ratios, 0%wt was the control group. Various methods were used to characterize TiO2-HAP. Subsequently, the changes in mechanical and optical properties of the samples were measured, and Cell Counting Kit-8 (CCK-8) and cell live-death staining were used to detect the cytotoxicity of the samples to human gingival fibroblasts (HGFs) in vitro. The contact angle of the specimens was evaluated. The photocatalytic antibacterial activity of modified PMMA against Candida albicans was studied using a biofilm accumulation test and scanning electron microscopy.

Results

TiO2-HAP nanocomposites have an acceptable structure. When the addition amount of TiO2-HAP is 1.0%wt, the PMMA material showed peak mechanical properties. When the additional amount is less than 1%wt, The patient is still aesthetically acceptable PMMA showed no significant cytotoxicity at doses below 2%wt. While TiO2-HAP modified PMMA containing only 1%wt showed up to 94% antibacterial efficiency against Candida albicans under visible light.

Conclusion

Therefore, it is inferred that the optimal photocatalytic antimicrobial and mechanical properties of PMMA materials are achieved by adding 1%wt TiO2-HAP without causing significant changes in cytotoxicity and optical properties.

Advancements in photodynamic inactivation: A comprehensive review of photosensitizers, mechanisms, and applications in food area

Food microbial contamination results in serious food safety issues and numerous food loss and waste, presenting one of the most significant challenges facing the global food system. Photodynamic inactivation (PDI) technology, which combines light and photosensitizers (PS) to provide antimicrobial effects, is an ideal nonthermal antimicrobial technique for the food industry. This review provides a comprehensive overview of PDI technology, beginning with the fundamental photoactivation principles of PS and the pathways of photoinduced reactive oxygen species (ROS) generation. PS is the most critical factor affecting PDI efficiency, which is categorized into three types: organic, metal oxide-, and carbon-based. This review systemically summarizes the photophysical properties, in vitro PDI performances, potential enhancement strategies, and the advantages and limitations of each type of PS. Furthermore, the antimicrobial mechanisms of the PDI technologies are analyzed at both microscopic and molecular levels. Finally, the current applications of PDI in various food systems are discussed, along with the associated challenges and opportunities. Overall, this review offers crucial insights into optimizing and advancing PDI technology, highlighting key challenges and suggesting future research directions to enhance the effectiveness and scalability of PDI for diverse food applications.

Enhanced photocatalytic dye detoxification by banana peel derived enzyme inherited ZnO/g-C3N4 nanocomposite: Validation by soil health and seed germination analyses

Development of bio-supported photocatalysts has become a pressing need in the field of environmental remediation. This work reports the synthesis of bio-enzyme (from banana peels) inherited (ZnO/g-C3N4)enzyme nanocomposite by simple soft chemical method and its photocatalytic degradation ability against the mixed dye (Methylene blue (MB) + Rhodamine-B (RhB)) under UV irradiation. Synthesized nanoparticles were characterized using experimental techniques XRD, FESEM, TEM, EDAX, XPS, UVvis-NIR spectroscopy and FTIR. The degradation efficiency of the (ZnO/g-C3N4)enzyme is 98% against MB component and 93% against the RhB component within the irradiation time of 75 min which is superior to bare ZnO, enzyme activated ZnO and g-C3N4. The presence of enzymes peroxidase, protease, cellulase, lipase and amylase in the nanocomposite is confirmed by enzyme quantitative study. The dye detoxification was confirmed by supplying the treated water to two different soils (sandy loam and clay) and investigating the soil health. The detoxification was further confirmed by applying the treated water to fenugreek (Trigonella foenum-graecum L., Fabaceae) seeds and analysing the seed germination. The observed complete detoxification of the mixed dye solution showed that the banana peel derived bio-enzyme inherited (ZnO/g-C3N4)enzyme nanocomposite can be considered as a desirable candidate for industrial dye waste water treatment.

N-doped MoS2 nanoflowers for the ultrasonic-vibration-driven high piezoelectric catalytic degradation

In this study, N-doped few-layer MoS2 piezocatalysts were successfully prepared by a one-pot hydrothermal method with urea as a nitrogen source. Benefiting from the optimized proportion of minority layers at edge positions and higher conductivity by N doping, the optimal N-doped few-layer MoS2 (120 mg of added urea) sample showed the optimal piezocatalytic activity for Rhodamine B (RhB) and levofloxacin (LEV), reaching 84.6 and 73.1% with the reaction kinetic rate constant of 0.020 86 and 0.017 05 min-1, respectively. In addition, the generation of superoxide radicals (·O2-) from the 120-MoS2 sample was determined to be greater than that from the 0-MoS2 sample in the piezocatalyst process by free radical scavenging experiments and electron paramagnetic resonance tests. Based on experimental data, a potential mechanism has been proposed to explain the enhanced piezocatalyst performance of N-doped few-layer MoS2. This research sheds new light on the development of efficient, cost-effective MoS2 piezoelectric catalysts through the doping of non-metallic dopants.

Influence of π-π interactions on organic photocatalytic materials and their performance

Currently, organic photocatalyst-based photocatalysis has garnered significant attention as an environmentally friendly and sustainable reaction system due to the preferable structural flexibility and adjustable optoelectronic features of organic photocatalysts. In addition, π-π interactions, as one of the common non-bonded interactions, play an important role in the structure and property adjustments of organic photocatalysts due to their unique advantages in modulating the electronic structure, facilitating charge migration, and influencing interfacial reactions. However, studies summarizing the relationship between the π-π interactions of organic photocatalysts and their photocatalytic performance are still rare. Therefore, in this review, we introduced the types of π-π interactions, characterization techniques, and different types of organic photocatalytic materials. Then, the influence of π-π interactions on photocatalysis and the modification strategies of π-π interactions were summarized. Finally, we discussed their influence on photocatalytic performance in different photocatalytic systems and analyzed the challenges and prospects associated with harnessing π-π interactions in photocatalysis. The review provides a clear map for understanding π-π interaction formation mechanism and its application in organic photocatalysts, offering useful guidance for researchers in this field.

Heterogeneous Interface Engineering of 2D Black Phosphorus-Based Materials for Enhanced Photocatalytic Performance

Photocatalysis has garnered significant attention as a sustainable approach for energy conversion and environmental management. 2D black phosphorus (BP) has emerged as a highly promising semiconductor photocatalyst owing to its distinctive properties. However, inherent issues such as rapid recombination of photogenerated electrons and holes severely impede the photocatalytic efficacy of single BP. The construction/stacking mode of BP with other nanomaterials decreases the recombination rate of carriers and extend its functionalities. Herein, from the perspective of atomic interface and electronic interface, the enhancement mechanism of photocatalytic performance by heterogeneous interface engineering is discussed. Based on the intrinsic properties of BP and corresponding photocatalytic principles, the effects of diverse interface characteristics (point, linear, and planar interface) and charge transfer mechanisms (type I, type II, Z-scheme, and S-scheme heterojunctions) on photocatalysis are summarized systematically. The modulation of heterogeneous interfaces and rational regulation of charge transfer mechanisms can enhance charge migration between interfaces and even maximize redox capability. Furthermore, research progress of heterogeneous interface engineering based on BP is summarized and their prospects are looked ahead. It is anticipated that a novel concept would be presented for constructing superior BP-based photocatalysts and designing other 2D photocatalytic materials.

A comprehensive review on TiO2-based heterogeneous photocatalytic technologies for emerging pollutants removal from water and wastewater: From engineering aspects to modeling approaches

The increasing presence of emerging pollutants (EPs) in water poses significant environmental and health risks, necessitating effective treatment solutions. Originating from industrial, agricultural, and domestic sources, these contaminants threaten ecological and public health, underscoring the urgent need for innovative and efficient treatment methods. TiO2-based semiconductor photocatalysts have emerged as a promising approach for the degradation of EPs, leveraging their unique band structures and heterojunction schemes. However, few studies have examined the synergistic effects of operating conditions on these contaminants, representing a key knowledge gap in the field. This review addresses this gap by exploring recent trends in TiO2-driven heterogeneous photocatalysis for water and wastewater treatment, with an emphasis on photoreactor setups and configurations. Challenges in scaling up these photoreactors are also discussed. Furthermore, Machine Learning (ML) models play a crucial role in developing predictive frameworks for complex processes, highlighting intricate temporal dynamics essential for understanding EPs behavior. This capability integrates seamlessly with Computational Fluid Dynamics (CFD) modeling, which is also addressed in this review. Together, these approaches illustrate how CFD can simulate the degradation of EPs by effectively coupling chemical kinetics, radiative transfer, and hydrodynamics in both suspended and immobilized photocatalysts. By elucidating the synergy between ML and CFD models, this study offers new insights into overcoming traditional limitations in photocatalytic process design and optimizing operating conditions. Finally, this review presents recommendations for future directions and insights on optimizing and modeling photocatalytic processes.

Novel Single Perovskite Material for Visible-Light Photocatalytic CO2 Reduction via Joint Experimental and DFT Study

Developing advanced and economically viable technologies for the capture and utilization of carbon dioxide (CO2) is crucial for sustainable energy production from fossil fuels. Converting CO2 into valuable chemicals and fuels is a promising approach to mitigate atmospheric CO2 levels. Among various methods, photocatalytic reduction stands out for its potential to reduce emissions and produce useful products. Here, novel perovskite ZnMoFeO3 (ZMFO) nanosheets are presented as promising semiconductor photocatalysts for CO2 reduction. Experimental results show that ZMFO has a narrow bandgap, exceptional visible light response, large specific surface area, high crystallinity, and various surface-active sites, leading to an impressive photocatalytic CO2 reduction activity of 24.87 µmolg-1h-1 and strong stability. Theoretical calculations reveal that CO2 conversion into CO and CH4 on the ZMFO surface follows formaldehyde and carbine pathways. This study provides significant insights into designing innovative perovskite oxide-based photocatalysts for economical and efficient CO2 reduction systems.

SbSeI for high-efficient photocatalytic degradation of multiple pollutants

Photocatalytic degradation is an effective technology for degrading water pollution that plays a significant role in environmental remediation. Ternary 2D ternary V-VI-VIIA semiconductors are ideal candidates for photocatalytic degradation of pollutants due to effective light absorption and high charge carrier mobility. In this work, high-quality SbSeI crystals were prepared using the chemical vapor transport (CVT) method and their photocatalytic degradation performance for multiple pollutants was studied. SbSeI exhibits excellent photocatalytic performance in the degradation of potassium dichromate (Cr (VI)), rhodamine B (RhB), tetracycline hydrochloride (TC-HCl) and methyl orange (MO). More than 98% of Cr (VI) and RhB can be removed after irradiation with an Xe lamp for 10 min and 40 min, respectively. The capture experiments and electron spin resonance results indicated that ·O2- plays a major role in reducing Cr (VI), while h+ plays a primary role in the degradation of MO, RhB and TC-HCl. Interestingly, the degradation rate of Cr (VI) is 1.3 times higher than that of a single pollutant system, and the degradation rate of RhB is 1.6 times higher, due to the enhanced separation and utilization of holes and electrons. The results demonstrate that SbSeI is a potential photocatalytic degradation material.

Coupling UiO-66 MOF with a Nanotubular Oxide Layer Grown on Ti-W Alloy Accelerates the Degradation of Hormones in Real Water Matrices

To enable the photoelectrocatalytic treatment of large volumes of water containing low concentrations of pollutants, this study introduces a hybrid photocatalyst, composed of nanotubular oxides grown on TixW alloy (x = 0.5 and 5.0 wt %) modified with UiO-66 MOF, for degradation of estrone (E1) and 17α-ethinyl estradiol (EE2). The oxide layer (Nt/TixW) was prepared via anodization, while UiO-66 nanoparticles were synthesized by using a solvothermal process. Different techniques for modifying nanotubular oxides were evaluated to maximize the photocatalytic activity and the sorption process. In photo(electro)catalytic experiments using low concentrations of E1 and EE2 synthetic solutions and UV-vis radiation (100 W/cm2), all modified materials exhibited approximately 40% higher degradation compared to the unmodified photocatalyst, keeping the same sequential performance of the photocatalysts (Nt/TiO2 < Nt/Ti-0.5W < Nt/Ti-5.0W) independent of the treatment. This enhancement was attributed to the MOF's increased hormone sorption, with no synergistic interaction observed between the photocatalyst and the adsorbent. In real water supply matrices, the photoelectrocatalytic removal rate of E1 using Nt/Ti-5.0W modified UiO-66 under UV-vis radiation and 1.3 V was 0.168 s-1, while for EE2, it was 0.310 min-1, approximately 1.78 and 18.21 times faster than obtained with the unmodified photocatalyst. The slower degradation rate of EE2 compared to that of E1 is attributed to the formation of denser intermediates that compete with smaller organic molecules in the real matrix. The cooperative effect between NT/TixW and UiO-66 favored the confinement of pollutants and by-products within the UiO-66 cavity, minimizing the diffusion effects and promoting the degradation of these compounds by the OH· radical generated at the oxide/solution interface. Among the tested electrodes, NT/Ti5W modified with UiO-66 demonstrated the highest efficiency and stability during the recycle tests. This highlights its promise for applications in photocatalytic processes for treating water supplies with low pollutant concentrations.

Heterojunction semiconductor nanocatalysts as cancer theranostics

Cancer nanotechnology is a promising area of cross-disciplinary research aiming to develop facile, effective, and noninvasive strategies to improve cancer diagnosis and treatment. Catalytic therapy based on exogenous stimulus-responsive semiconductor nanomaterials has shown its potential to address the challenges under the most global medical needs. Semiconductor nanocatalytic therapy is usually triggered by the catalytic action of hot electrons and holes during local redox reactions within the tumor, which represent the response of nontoxic semiconductor nanocatalysts to pertinent internal or external stimuli. However, careful architecture design of semiconductor nanocatalysts has been the major focus since the catalytic efficiency is often limited by facile hot electron/hole recombination. Addressing these challenges is vital for the progress of cancer catalytic therapy. In recent years, diverse strategies have been developed, with heterojunctions emerging as a prominent and extensively explored method. The efficiency of charge separation under exogenous stimulation can be heightened by manipulating the semiconducting performance of materials through heterojunction structures, thereby enhancing catalytic capabilities. This review summarizes the recent applications of exogenous stimulus-responsive semiconducting nanoheterojunctions for cancer theranostics. The first part of the review outlines the construction of different heterojunction types. The next section summarizes recent designs, properties, and catalytic mechanisms of various semiconductor heterojunctions in tumor therapy. The review concludes by discussing the challenges and providing insights into their prospects within this dynamic and continuously evolving field of research.

Photocatalytic Enhancement and Recyclability in Visible-Light-Responsive 2D/2D g-C3N4/BiOI p-n Heterojunctions via a Z-Scheme Charge Transfer Mechanism

With the intensification of the energy crisis and the growing concern over environmental pollution, particularly the discharge of organic dye pollutants in industrial wastewater, photocatalytic degradation of these contaminants using solar energy has emerged as an effective, eco-friendly solution. In this study, we successfully synthesized 2D/2D g-C3N4/BiOI p-n heterojunctions via a simple precipitation method and a high-temperature calcination method. The unique 2D structures of g-C3N4 nanosheets (NSs) and BiOI NSs, coupled with the synergistic effect between the two materials, significantly enhanced the photocatalytic degradation performance of the heterojunctions under simulated sunlight. The band structures, as determined by Tauc curves, Mott-Schottky curves and XPS-VB analysis, revealed a Z-scheme charge transfer mechanism that efficiently reduced charge carrier recombination and improved electron-hole separation. The photocatalytic activity of 2D/2D g-C3N4/BiOI p-n heterojunctions for rhodamine B (Rh B) degradation reached 99.7% efficiency within 60 min, a 2.37-fold and 1.27-fold improvement over pristine BiOI NSs and g-C3N4 NSs, respectively. Furthermore, the heterojunction exhibited excellent recyclability stability, with the degradation efficiency decreasing by only 1.2% after five cycles. Radical scavenging experiments confirmed the involvement of superoxide radicals (∙O2-) and hydroxyl radicals (∙OH) as the primary reactive species in the degradation process. This work highlights the potential of 2D/2D g-C3N4/BiOI p-n heterojunctions for efficient photocatalytic applications in environmental remediation.

One-Step Construction of Hierarchical Porous and Defect-Rich Zn2+-Doped NH2-MIL-125(Ti) to Enhance Photocatalytic Degradation of Tetracycline Hydrochloride

The development of efficient metal-organic framework (MOF) photocatalysts for the degradation of tetracycline hydrochloride (TC) is crucial for environmental and public health. Herein, NH2-MIL-125(Ti) flakes (namely, ZnxTi1-x-NML), featuring defect-rich and Zn2+-doping, were synthesized using a one-step solvothermal method. For the first time, the crystal structure of Zn-doped NML was determined by combining extended X-ray absorption with fine structure spectroscopy. The formation mechanisms of the flake morphology with hierarchical porous structures were thoroughly investigated. Compared to NH2-MIL-125(Ti), Zn0.15Ti0.85-NML achieved a 3.4-fold increase in removal of TC under simulated sunlight. The adjusted electronic structure enhances superoxide radical production, coupled with a flake-like and porous architecture that promotes reaction sites, improved mass transfer, and reduced charge distances. Combined with theoretical calculations of the density of states and electrostatic potential, the ligand-metal-metal charge transfer process was elucidated. The possible pathway for the photocatalytic degradation of TC by Zn0.15Ti0.85-NML was further speculated. Moreover, the safety of the photocatalytic pathway was assessed by predicting the toxicity of the degradation intermediates. Our findings link the structure of MOFs to their catalytic efficiency, guiding the creation of sustainable photocatalysts.

Biogenic fabrication of NiO-ZnO-CaO ternary nanocomposite using Azadirachta Indica (Neem) leaves extract with proficient photocatalytic degradation of rhodamine B dye

In the current study, a ternary nanocomposite (NiO–ZnO–CaO) was successfully synthesized through the co-precipitation method using Azadirachta Indica (neem) leaves extract as green approach. The characterization of prepared nanocomposite was conducted using FT-IR, XRD, SEM and EDS to determine the metal oxides absorption bands, structural properties, elemental composition, and surface morphology of the nanocomposite. FT-IR analysis revealed characteristic vibrational peaks at 621, 684, and 721 cm−1, corresponding to Ni-O, Zn-O, and Ca-O bond vibrations, respectively. XRD patterns showed distinct diffraction peaks, indicative of the hexagonal structure of ZnO and the cubic structures of NiO and CaO. EDS analysis confirmed the presence of calcium, nickel, zinc, and oxygen with weight percentages of 9.2%, 14.4%, 15.1%, and 20.9%, respectively. SEM images displayed an irregular cube like morphology with noticeable clustering within the nanocomposite. The ternary nanocomposite was employed as photocatalyst and exhibited degradation efficiency (97%) against rhodamine B dye under 180 min of irradiation time. The kinetic studies of dye on the photocatalyst surface were accurately explained by a first-order kinetics model, with all R2 > 95, signifying a strong correlation between time and dye concentration. The potocatalytic degradation mechanism of ternary nanocomposite was proposed based on band positions of of NiO, ZnO and CaO forming double type II heterojunction. Furthermore, species trapping experiments employing different scavengers were carried out, revealing the active participation of OH● and O2●─ radicals in the degradation mechanism.

The Influence of Heat Treatment on the Photoactivity of Amine-Modified Titanium Dioxide in the Reduction of Carbon Dioxide

Modification of titanium dioxide using ethylenediamine (EDA), diethylamine (DEA), and triethylamine (TEA) has been studied. As the reference material, titanium dioxide prepared by the sol-gel method using titanium(IV) isopropoxide as a precursor was applied. The preparation procedure involved heat treatment in the microwave reactor or in the high-temperature furnace. The obtained samples have been characterized in detail. The phase composition was determined through the X-ray diffraction method, and the average crystallite size was calculated based on it. Values for specific surface areas and the total pore volumes were calculated based on the isotherms obtained through the low-temperature nitrogen adsorption method. The bang gap energy was estimated based on Tauc's plots. The influence of the type and content of amine, as well as heat treatment on the photocatalytic activity of modified titanium dioxide in the photocatalytic reduction of carbon dioxide, was determined and discussed. It was clear that, regardless of the amount and content of amine introduced, the higher photoactivity characterized the samples prepared in the microwave reactor. The highest amounts of hydrogen, carbon monoxide, and methane have been achieved using triethylamine-modified titanium dioxide.

Photorefinery of Biomass and Plastics to Renewable Chemicals using Heterogeneous Catalysts

The photocatalytic conversion of biomass and plastic waste provides opportunities for sustainable fuel and chemical production. Heterogeneous photocatalysts, typically composed of semiconductors with distinctive redox properties in their conduction band (CB) and valence band (VB), facilitate both the oxidative and reductive valorization of organic feedstocks. This article provides a comprehensive overview of recent advancements in the photorefinery of biomass and plastics from the perspective of the redox properties of photocatalysts. We explore the roles of the VB and CB in enhancing the value-added conversion of biomass and plastics via various pathways. Our aim is to bridge the gap between photocatalytic mechanisms and renewable carbon feedstock valorization, inspiring further development in photocatalytic refinery of biomass and plastics.

Defect-engineered dual Z-scheme core-shell MoS2/WO3-x/AgBiS2 for antibiotic and dyes degradation in photo and night catalysis: Mechanism and pathways

Water pollution caused by antibiotics and synthetic dyes and imminent energy crises due to limited fossil fuel resources are issues of contemporary decades. Herein, we address them by enabling the multifunctionality in dual Z-scheme MoS2/WO3-x/AgBiS2 across photolysis, photo Fenton-like, and night catalysis. Defect, basal, and facet-engineered WO3-x is modified with MoS2 and AgBiS2, which extended its photoresponse from the UV-NIR region, inhibited carrier recombination, and reduced carrier transfer resistance. The electric field rearrangement leads to a flow of electrons from MoS2 and AgBiS2 to WO3-x and intensifies the electron population, which is crucial for night catalysis. When MoS2/WO3-x/AgBiS2 was employed against doxycycline hydrochloride (DOXH), it removed 95.65, 81.11, and 77.92 % of DOXH in 100 min during photo-Fenton (PFR), night-Fenton (NFR), and photocatalytic (PCR) reactions, respectively. It also effectively removed 91.91, 98.17, 99.01, and 98.99 % of rhodamine B (RhB), Congo red (CR), methylene blue (MB), and methylene orange (MO) in Fenton reactions, respectively. ESR analysis consolidates the ROS generation feature of MoS2/WO3-x/AgBiS2 using H2O2 with and without irradiation. This work provides a strategy to eliminate the deficiencies of WO3-x and is conducive to the evolution of applications seeking to combat environmental and energy crises.

Physicochemical reactions in e-waste recycling

Electronic waste (e-waste) recycling is becoming a global concern owing to its immense quantity, hazardous character and the potential loss of valuable metals. The many processes involved in e-waste recycling stem from a mixture of physicochemical reactions, and understanding the principles of these reactions can lead to more efficient recycling methods. In this Review, we discuss the principles behind photochemistry, thermochemistry, mechanochemistry, electrochemistry and sonochemistry for metal recovery, polymer decomposition and pollutant elimination from e-waste. We also discuss how these processes induce or improve reaction rates, selectivity and controllability of e-waste recycling based on thermodynamics and kinetics, free radicals, chemical bond energy, electrical potential regulation and more. Lastly, key factors, limitations and suggestions for improvements of these physicochemical reactions for e-waste recycling are highlighted, wherein we also indicate possible research directions for the future.

Synthesis of visible-light-activated CeO2-x/BiCrO3 photocatalysts with S-scheme mechanism: Effectual performances in detoxification of various antibiotics and organic pollutants

In today's world, the development of an efficient water treatment strategy requires a prospective approach for the production of active and stable photocatalysts. The construction of heterojunctions with different semiconductors is a promising procedure for improving photocatalytic performances. In the present research, binary CeO2-x/BiCrO3 photocatalysts were synthesized using a hydrothermal route preceded by a calcination step. The CeO2-x/BiCrO3 (15%) photocatalyst proved its unique performance of 29.3, 11.4, 11.7, and 23.0 times better than CeO2 for photodegradation of respectively tetracycline hydrochloride (TCH), metronidazole (MET), azithromycin (AZM), and cephalexin (CPN), as antibiotic pollutants, upon visible light. The effective photocatalytic ability, which was caused by the impressive suppression of charge carriers, can be understood by the developed S-scheme mechanism. Moreover, the lower resistance of CeO2-x/BiCrO3 (15%) compared to CeO2, CeO2-x, and BiCrO3 against the charges transfer was another confirmation for boosted photocatalytic performance of the CeO2-x/BiCrO3 (15%) nanocomposite. Ultimately, the boosted activity, repeated utilization for five runs, and biocompatibility confirmation of the purified solution through pinto bean cultivation exhibited that CeO2-x/BiCrO3 photocatalysts could have the promising capability for detoxification of polluted water.

Controlling nanoparticle placement in Au/TiO2 inverse opal photocatalysts

Gold nanoparticle-loaded titania (Au/TiO2) inverse opals are highly ordered three-dimensional photonic structures with enhanced photocatalytic properties. However, fine control over the placement of the Au nanoparticles in the inverse opal structures remains challenging with traditional preparative methods. Here, we present a multi-component co-assembly strategy to prepare high-quality Au/TiO2 inverse opal films in which Au nanoparticles are either located on, or inside the TiO2 matrix, as verified using electron tomography. We report that Au nanoparticles embedded in the TiO2 support exhibit enhanced thermal and mechanical stability compared to non-embedded nanoparticles that are more prone to both leaching and sintering.

Machine learning analysis to interpret the effect of the photocatalytic reaction rate constant (k) of semiconductor-based photocatalysts on dye removal

Photocatalytic reactions with semiconductor-based photocatalysts have been investigated extensively for application to wastewater treatment, especially dye degradation, yet the interactions between different process parameters have rarely been reported due to their complicated reaction mechanisms. Hence, this study aims to discern the impact of each factor, and each interaction between multiple factors on reaction rate constant (k) using a decision tree model. The dyes selected as target pollutants were indigo and malachite green, and 5 different semiconductor-based photocatalysts with 17 different compositions were tested, which generated 34 input features and 1527 data points. The Boruta Shapley Additive exPlanations (SHAP) feature selection for the 34 inputs found that 11 inputs were significantly important. The decision tree model exhibited for 11 input features with an R2 value of 0.94. The SHAP feature importance analysis suggested that photocatalytic experimental conditions, with an importance of 59%, was the most important input category, followed by atomic composition (39%) and physicochemical properties (2%). Additionally, the effects on k of the synergy between the metal cocatalysts and important experimental conditions were confirmed by two feature SHAP dependence plots, regardless of importance order. This work provides insight into the single and multiple factors that affect reaction rate and mechanism.

Sulfur-Doped g-C3N4 Heterojunctions for Efficient Visible Light Degradation of Methylene Blue

The discharge of synthetic dyes from different industrial sources has become a global issue of concern. Enormous amounts are released into wastewater each year, causing concerns due to the high toxic consequences. Photocatalytic semiconductors appear as a green and sustainable form of remediation. Among them, graphitic carbon nitride (g-C3N4) has been widely studied due to its low cost and ease of fabrication. In this work, the synthesis, characterization, and photocatalytic study over methylene blue of undoped, B/S-doped, and exfoliated heterojunctions of g-C3N4 are presented. The evaluation of the photocatalytic performance showed that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75 mass % of S-doped (g-C3N4) present enhanced activity with an apparent reaction rate constant (kapp) of 1.92 × 10-2 min-1 for the 75% sample. These results are supported by photoluminescence (PL) experiments showing that this heterojunction presents the less probable electron-hole recombination. UV-vis diffuse reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS) allowed the calculation of the band-gap and the valence band positions, suggesting a band structure diagram describing a type I heterojunction. The photocatalytic activities calculated demonstrate that this property is related to the surface area and porosity of the samples, the semiconductor nature of the g-C3N4 structure, and, in this case, the heterojunction that modifies the band structure. These results are of great importance considering that scarce reports are found concerning exfoliated B/S-doped heterojunctions.

Tocilizumab degradation via photo-catalytic ozonation process from aqueous

Following the advent of the coronavirus pandemic, tocilizumab has emerged as a potentially efficacious therapeutic intervention. The utilization of O3-Heterogeneous photocatalytic process (O3-HPCP) as a hybrid advanced oxidation technique has been employed for the degradation of pollutants. The present study employed a solvothermal technique for the synthesis of the BiOI-MOF composite. The utilization of FTIR, FESEM, EDAX, XRD, UV-vis, BET, TEM, and XPS analysis was employed to confirm the exceptional quality of the catalyst. the study employed an experimental design, subsequently followed by the analysis of collected data in order to forecast the most favorable conditions. The purpose of this study was to investigate the impact of several factors, including reaction time (30-60 min), catalyst dose (0.25-0.5 mg/L), pH levels (4-8), ozone concentration (20-40 mMol/L), and tocilizumab concentration (10-20 mg/L), on the performance of O3-HPCP. The best model was discovered by evaluating the F-value and P-value coefficients, which were found to be 0.0001 and 347.93, respectively. In the given experimental conditions, which include a catalyst dose of 0.46 mg/L, a reaction time of 59 min, a pH of 7.0, and an ozone concentration of 32 mMol/L, the removal efficiencies were found to be 92% for tocilizumab, 79.8% for COD, and 59% for TOC. The obtained R2 value of 0.98 suggests a strong correlation between the observed data and the predicted values, indicating that the reaction rate followed first-order kinetics. The coefficient of synergy for the degradation of tocilizumab was shown to be 1.22. The catalyst exhibited satisfactory outcomes, but with a marginal reduction in efficacy of approximately 3%. The sulfate ion (SO42-) exhibited no influence on process efficiency, whereas the nitrate ion (NO3-) exerted the most significant impact among the anions. The progress of the process was impeded by organic scavengers, with methanol exhibiting the most pronounced influence and sodium azide exerting the least significant impact. The efficacy of pure BiOI and NH2-MIL125 (Ti) was diminished when employed in their pure form state. The energy consumption per unit of degradation, denoted as EEO, was determined to be 161.8 KWh/m3-order.

Research progress of TiO2-based photocatalytic degradation of wastewater: bibliometric analysis

The pollution caused by modernization and industrialization has caused serious harm to the biodiversity of the earth. TiO2-based photocatalyst has been widely studied as an effective and sustainable water environment remediation material. In this study, we analyzed the status and research trends of TiO2-based photocatalytic degradation of wastewater in depression from 2003 to 2023 to provide a reference for further research. "Doping", "Modification" and "Heterojunction" were used as keywords, and 817 related academic literatures were screened out by using Web of Science database. Through the visualization software VOSviewer and CiteSpace, the authors, institutions and literature keywords were clustered. The results show that since 2008, the annual number of published papers on TiO2-based photocatalytic degradation of wastewater has increased from 9 to 114. Among them, China has published 432 articles and made great contributions, and there are many representative research teams. Chinese universities are the main body to study TiO2-based photocatalytic degradation of wastewater, but the cooperation between universities is not as close as that abroad. This paper comprehensively analyzes the research hotspots of TiO2-based photocatalytic degradation of wastewater, such as the doping of TiO2 and the construction of different types of heterojunctions of TiO2. It is expected that these analysis results will provide new research ideas for researchers to carry out future research on related topics and let researchers know in-depth research institutions and possible collaborators to conduct academic exchanges and discussions with active institutions.

A Review on Pulsed Laser Fabrication of Nanomaterials in Liquids for (Photo)catalytic Degradation of Organic Pollutants in the Water System

The water pollution caused by the release of organic pollutants has attracted remarkable attention, and solutions for wastewater treatment are being developed. In particular, the photocatalytic removal of organic pollutants in water systems is a promising strategy to realize the self-cleaning of ecosystems under solar light irradiation. However, at present the semiconductor-based nanocatalysts can barely satisfy the industrial requirements because their wide bandgaps restrict the effective absorption of solar light, which needs an energy band modification to boost the visible light harvesting via surface engineering. As an innovative approach, pulsed laser heating in liquids has been utilized to fabricate the nanomaterials in catalysis; it demonstrates multi-controllable features, such as size, morphology, crystal structure, and even optical or electrical properties, with which photocatalytic performances can be precisely optimized. In this review, focusing on the powerful heating effect of pulsed laser irradiation in liquids, the functional nanomaterials fabricated by laser technology and their applications in the catalytic degradation of various organic pollutants are summarized. This review not only highlights the innovative works of pulsed laser-prepared nanomaterials for organic pollutant removal in water systems, such as the photocatalytic degradation of organic dyes and the catalytic reduction of toxic nitrophenol and nitrobenzene, it also critically discusses the specific challenges and outlooks of this field, including the weakness of the produced yields and the relevant automatic strategies for massive production.

Hydrogen Bond-Induced Activation of Photocatalytic and Piezophotocatalytic Properties in Calcium Nitrate Doped Electrospun PVDF Fibers

In this study, polyvinylidene fluoride (PVDF) fibers doped with hydrated calcium nitrate were prepared using electrospinning. The samples were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD), optical spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Raman, and photoluminescence (PL) spectroscopy. The results are complementary and confirm the presence of chemical hydrogen bonding between the polymer and the dopant. Additionally, there was a significant increase in the proportion of the electroactive polar beta phase from 72 to 86%. It was shown that hydrogen bonds acted as a transport pathway for electron capture by the conjugated salt, leading to more than a three-fold quenching of photoluminescence. Furthermore, the optical bandgap of the composite material narrowed to the range of visible light energies. For the first time, it the addition of the salt reduced the energy of the PVDF exciton by a factor of 17.3, initiating photocatalytic activity. The calcium nitrate-doped PVDF exhibited high photocatalytic activity in the degradation of methylene blue (MB) under both UV and visible light (89 and 44%, respectively). The reaction rate increased by a factor of 2.4 under UV and 3.3 under visible light during piezophotocatalysis. The catalysis experiments proved the efficiency of the membrane design and mechanisms of catalysis are suggested. This study offers insight into the nature of chemical bonds in piezopolymer composites and potential opportunities for their use.

Experimental and computational study of metal oxide nanoparticles for the photocatalytic degradation of organic pollutants: a review

Photocatalysis is a more proficient technique that involves the breakdown or decomposition of different organic contaminants, various dyes, and harmful viruses and fungi using UV or visible light solar spectrum. Metal oxides are considered promising candidate photocatalysts owing to their low cost, efficiency, simple fabricating method, sufficient availability, and environment-friendliness for photocatalytic applications. Among metal oxides, TiO2 is the most studied photocatalyst and is highly applied in wastewater treatment and hydrogen production. However, TiO2 is relatively active only under ultraviolet light due to its wide bandgap, which limits its applicability because the production of ultraviolet is expensive. At present, the discovery of a photocatalyst of suitable bandgap with visible light or modification of the existing photocatalyst is becoming very attractive for photocatalysis technology. However, the major drawbacks of photocatalysts are the high recombination rate of photogenerated electron-hole pairs, the ultraviolet light activity limitations, and low surface coverage. In this review, the most commonly used synthesis method for metal oxide nanoparticles, photocatalytic applications of metal oxides, and applications and toxicity of different dyes are comprehensively highlighted. In addition, the challenges in the photocatalytic applications of metal oxides, strategies to suppress these challenges, and metal oxide studied by density functional theory for photocatalytic applications are described in detail.

Recent advances in the removal of emerging contaminants from water by novel molecularly imprinted materials in advanced oxidation processes-A review

Recently, there has been a global focus on effectively treating emerging contaminants (ECs) in water bodies. Advanced oxidation processes (AOPs) are the primary technology used for ECs removal. However, the low concentrations of ECs make it difficult to overcome the interference of background substances in complex water quality, which limits the practical application of AOPs. To address this limitation, many researchers are developing new catalysts with preferential adsorption. Molecular imprinting technology (MIT) combined with conventional catalysts has been found to effectively enhance the selectivity of catalysts for the targeted catalytic degradation of pollutants. This review presents a comprehensive summary of the progress made in research on molecularly imprinted polymers (MIPs) in the selective oxidation of ECs in water. The preparation methods, principles, and control points of novel MIP catalysts are discussed. Furthermore, the performance and mechanism of the catalysts in photocatalytic oxidation, electrocatalytic oxidation, and persulfate activation are analyzed with examples. The possible ecotoxicological risks of MIP catalysts are also discussed. Finally, the challenges and prospects of applying MIP catalysts in AOP are presented along with proposed solutions. This review provides a better understanding of using MIP catalysts in AOPs to target the degradation of ECs.

Recent advances on catalysts for photocatalytic selective hydrogenation of nitrobenzene to aniline

Selective hydrogenation of nitrobenzene (SHN) is an important approach to synthesize aniline, an essential intermediate with extremely high research significance and value in the fields of textiles, pharmaceuticals and dyes. SHN reaction requires high temperature and high hydrogen pressure via the conventional thermal-driven catalytic process. On the contrary, photocatalysis provides an avenue to achieve high nitrobenzene conversion and high selectivity towards aniline at room temperature and low hydrogen pressure, which is in line with the sustainable development strategies. Designing efficient photocatalysts is a crucial step in SHN. Up to now, several photocatalysts have been explored for photocatalytic SHN, such as TiO2, CdS, Cu/graphene and Eosin Y. In this review, we divide the photocatalysts into three categories based on the characteristics of the light harvesting units, including semiconductors, plasmonic metal-based catalysts and dyes. The recent progress of the three categories of photocatalysts is summarized, the challenges and opportunities are pointed out and the future development prospects are described. It aims to give a clear picture to the catalysis community and stimulate more efforts in this research area.