Plasma Cu-decorated TiO2-x/CoP particle-level hierarchical heterojunctions with enhanced photocatalytic-photothermal performance

Efficient Charge Separation in Ag/PCN/UPDI Ternary Heterojunction for Optimized Photothermal-Photocatalytic Performance via Tandem Electric Fields

Charge separation driven by the internal electric field is a research hotspot in photocatalysis. However, it remains challenging to accurately control the electric field to continuously accelerate the charge transfer. Herein, a strategy of constructing a tandem electric field to continuously accelerate charge transfer in photocatalysts is proposed. The plasma electric field, interface electric field, and intramolecular electric field are integrated into the Ag/g-C3N4/urea perylene imide (Ag/PCN/UPDI) ternary heterojunction to achieve faster charge separation and longer carrier lifetime. The triple electric fields function as three accelerators on the charge transport path, promoting the separation of electron-hole pairs, accelerating charge transfer, enhancing light absorption, and increasing the concentration of energetic electrons on the catalyst. The H2 evolution rate of Ag/PCN/UPDI is 16.8 times higher than that of pristine PDI, while the degradation rate of oxytetracycline is increased by 4.5 times. This new strategy will provide a groundbreaking idea for the development of high-efficiency photocatalysts.

Hollow g-C3N4@Ag3PO4 Core-Shell Nanoreactor Loaded with Au Nanoparticles: Boosting Photothermal Catalysis in Confined Space

Low solar energy utilization efficiency and serious charge recombination remain major challenges for photocatalytic systems. Herein, a hollow core-shell Au/g-C3N4@Ag3PO4 photothermal nanoreactor is successfully prepared by a two-step deposition method. Benefit from efficient spectral utilization and fast charge separation induced by the unique hollow core-shell heterostructure, the H2 evolution rate of Au/g-C3N4@Ag3PO4 is 16.9 times that of the pristine g-C3N4, and the degradation efficiency of tetracycline is increased by 88.1%. The enhanced catalytic performance can be attributed to the ordered charge movement on the hollow core-shell structure and a local high-temperature environment, which effectively accelerates the carrier separation and chemical reaction kinetics. This work highlights the important role of the space confinement effect in photothermal catalysis and provides a promising strategy for the development of the next generation of highly efficient photothermal catalysts.

Guiding the Driving Factors on Plasma Super-Photothermal S-Scheme Core-Shell Nanoreactor to Enhance Photothermal Catalytic H2 Evolution and Selective CO2 Reduction

Light-induced heat has a non-negligible role in photocatalytic reactions. However, it is still challenging to design highly efficient catalysts that can make use of light and thermal energy synergistically. Herein, the study proposes a plasma super-photothermal S-scheme heterojunction core-shell nanoreactor based on manipulation of the driving factors, which consists of α-Fe2 O3 encapsulated by g-C3 N4 modified with gold quantum dots. α-Fe2 O3 can promote carrier spatial separation while also acting as a thermal core to radiate heat to the shell, while Au quantum dots transfer energetic electrons and heat to g-C3 N4 via surface plasmon resonance. Consequently, the catalytic activity of Au/α-Fe2 O3 @g-C3 N4 is significantly improved by internal and external double hot spots, and it shows an H2 evolution rate of 5762.35 µmol h-1 g-1 , and the selectivity of CO2 conversion to CH4 is 91.2%. This work provides an effective strategy to design new plasma photothermal catalysts for the solar-to-fuel transition.

Synergistic activation of P and orbital coupling effect for ultra-sensitive and selective electrochemical detection of Cd(II) over Fe-doped CoP

Despite significant advancements in the detection of cadmium (Cd(II)) based on nanomaterial adsorbability, limited research has been conducted on ultra-sensitive and selective detection mechanisms, resulting in a lack of guidance for designing efficient interface materials to detect Cd(II). Herein, reductive Fe doping on CoP facilitates an efficient Fe-Co-P electron transfer path, which renders P the electron-rich site and subsequently splits a new orbital peak that matches with that of Cd(II) for excellent electrochemical performance. The sensitivity of Cd(II) was remarkably up to 109.75 μA μM-1 on the Fe-CoP modified electrode with excellent stability and repeatability, surpassing previously reported findings. Meanwhile, the electrode exhibits exceptional selectivity towards Cd(II) ions compared to some bivalent heavy metal ions (HMIs). Moreover, X-ray absorption fine structure (XAFS) analysis reveals the interaction between P and Cd(II), which is further verified via density functional theory (DFT) calculation with the new hybrid peaks resulting from the splitting peak of P atoms coupled with the orbital energy level of Cd(II). Generally, doping engineering for specific active sites and regulation of orbital electrons not only provides valuable insights for the subsequent regulation of electronic configuration but also lays the foundation for customizing highly sensitive and selectivity sensors.

Construction of Photothermo-Electro Coupling Field Based on Surface Modification of Hydrogenated TiO2 Nanotube Array Photoanode and Its Improved Photoelectrochemical Water Splitting

Solar water splitting has gained increasing attention in converting solar energy into green hydrogen energy. However, the construction of a photothermo-electro coupling field by harnessing light-induced heat and its enhancement on solar water splitting were seldom studied. Herein, we developed a full-spectrum responsive photoanode by depositing CdxZn1-xS onto the surface of hydrogenated TiO2 nanotube array (H-TNA), followed by modification with Ni2P. The resulting ternary photoanode exhibits a photocurrent density of 4.99 mA·cm-2 at 1.23 V vs. RHE with photoinduced heating, which is 11.9-fold higher than that of pristine TNA, with an optimal ABPE of 2.47%. The characterization results demonstrate that the ternary photoanode possesses superior full-spectrum absorption and efficient photogenerated carrier separation driven by the interface electric fields. Additionally, Ni2P reduces the hole injection barrier and increases surface active sites, accelerating the consumption of holes accumulating on the relatively unstable CdxZn1-xS to simultaneously improve the activity and stability of water splitting. Moreover, temperature-dependent measurements reveal that H-TNA and Ni2P significantly motivate the photothermal conversion to construct a photothermo-electro coupling field, optimizing photoelectric conversion and charge carrier-induced surface reactions. This work contributes to understanding the synergistic effect of the photothermo-electro coupling field on the photoelectrochemical water splitting.

Easily Repairable and High-Performance Carbon Nanostructure Absorber for Solar Photothermoelectric Conversion and Photothermal Water Evaporation

Carbon materials are a category of broadband solar energy harvesting materials that can convert solar energy into heat under irradiation, which can be used for photothermal water evaporation and photothermoelectric power generation. However, destruction of the carbon nanostructure during usage will significantly decrease the light-trapping performance and, thus, limit their practical applications. In this article, an easily repairable carbon nanostructure absorber with full-solar-spectrum absorption and a hierarchically porous structure is prepared. The carbon absorber shows a superhigh light absorption of above 97% across the whole solar spectrum because of multiple scatterings within the carbon nanostructure and photon interaction with the carbon nanoparticles. The excellent light absorption performance directly leads to a good photothermal effect. As a consequence, the carbon absorber integrated with a thermoelectric module can obtain a large power (133.3 μW cm^-2) output under 1 sun. In addition, the carbon absorber combined with the sponge can achieve a high photothermal water evaporation efficiency of 83.6% under 1 sun. Its high-efficiency solar-to-electricity and photothermal water evaporation capabilities demonstrate that the carbon absorber with superhigh absorption, simple fabrication, and facile repairability shows great potential for practical fresh water production and electric power generation.

Recent Advances in Black TiO2 Nanomaterials for Solar Energy Conversion

Titanium dioxide (TiO₂) nanomaterials have been widely used in photocatalytic energy conversion and environmental remediation due to their advantages of low cost, chemical stability, and relatively high photo-activity. However, applications of TiO₂ have been restricted in the ultraviolet range because of the wide band gap. Broadening the light absorption of TiO₂ nanomaterials is an efficient way to improve the photocatalytic activity. Thus, black TiO₂ with extended light response range in the visible light and even near infrared light has been extensively exploited as efficient photocatalysts in the last decade. This review represents an attempt to conclude the recent developments in black TiO₂ nanomaterials synthesized by modified treatment, which presented different structure, morphological features, reduced band gap, and enhanced solar energy harvesting efficiency. Special emphasis has been given to the newly developed synthetic methods, porous black TiO₂, and the approaches for further improving the photocatalytic activity of black TiO₂. Various black TiO₂, doped black TiO₂, metal-loaded black TiO₂ and black TiO₂ heterojunction photocatalysts, and their photocatalytic applications and mechanisms in the field of energy and environment are summarized in this review, to provide useful insights and new ideas in the related field.

Plasma Ag-Modified α-Fe2O3/g-C3N4 Self-Assembled S-Scheme Heterojunctions with Enhanced Photothermal-Photocatalytic-Fenton Performances

Low spectral utilization and charge carrier compounding limit the application of photocatalysis in energy conversion and environmental purification, and the rational construction of heterojunction is a promising strategy to break this bottleneck. Herein, we prepared surface-engineered plasma Ag-modified α-Fe₂O₃/g-C₃N₄ S-Scheme heterojunction photothermal catalysts by electrostatic self-assembly and light deposition strategy. The local surface plasmon resonance effect induced by Ag nanoparticles broadens the spectral response region and produces significant photothermal effects. The temperature of Ag/α-Fe₂O₃/g-C₃N₄ powder is increased to 173 °C with irradiation for 90 s, ~3.2 times higher than that of the original g-C₃N₄. The formation of 2D/2D structured S-Scheme heterojunction promotes rapid electron-hole transfer and spatial separation. Ternary heterojunction construction leads to significant enhancement of photocatalytic performance of Ag/α-Fe₂O₃/g-C₃N₄, the H₂ photocatalytic generation rate up to 3125.62 µmol g^-1 h^-1, which is eight times higher than original g-C₃N₄, and the photocatalytic degradation rate of tetracycline to reach 93.6%. This thermally assisted photocatalysis strategy improves the spectral utilization of conventional photocatalytic processes and provides new ideas for the practical application of photocatalysis in energy conversion and environmental purification.

Annealing and Plasma Effects on the Structural and Photocatalytic Properties of TiO2 Fibers Produced by Electrospinning

In this study, a combined method of heat treatment and plasma surface modification was used to improve the nanostructures and photocatalytic activity of electrospun TiO2 fibers. Based on the tuning effect of the annealing temperature from 500 to 800 °C, further improvements via the generation of H2 radiofrequency plasma reactions on the fiber’s surface were investigated. It was found that the anatase–rutile phase transition starts to occur at around 700 °C, which is higher than the common temperature for TiO2. The interfacial effect is generated by the symbiosis relationship between these two phases in the fibers, which can enhance photocatalytic activity since the anatase–rutile heterojunction in mixed-phase TiO2 is formed. The dramatic rise in oxygen vacancies on the fiber’s surface is created by the H2 plasma; this leads to the number of trapped electrons increasing and results in an accelerated separation between the photogenerated electrons and holes. Therefore, the photocatalytic mechanism, including the anatase–rutile heterojunction and the TiO2 fiber band structure containing oxygen vacancies, is predicted. The degradation rate was significantly enhanced (1.5 times) by increasing the annealing temperature up to 700 °C, which can be further improved upon after treatment with surface H2 plasma.

Integrating Reactive Chlorine Species Generation with H2 Evolution in a Multifunctional Photoelectrochemical System for Low Operational Carbon Emissions Saline Sewage Treatment

Conventional wastewater treatment plants (WWTPs) suffer from high carbon emissions and are inefficient in removing emerging organic pollutants (EOPs). Consequently, we have developed a low operational carbon emissions multifunctional photoelectrochemical (PEC) system for saline sewage treatment to simultaneously remove organic pollutants, ammonia, and bacteria, coupled with H₂ evolution. A reduced BiVO₄ (r-BiVO₄) photoanode with enhanced PEC properties, ascribed to constructing sufficient oxygen vacancies and V⁴⁺ species, was synthesized for the aforementioned technique. The PEC/r-BiVO₄ process could treat saline sewage to meet local WWTPs' discharge standard in 40 min at 2.0 V vs Ag/AgCl and completely degrade carbamazepine (one of EOPs), coupled with 633 μmol of H₂ production; 93.29% reduction in operational carbon emissions and 77.82% decrease in direct emissions were achieved by the PEC/r-BiVO₄ process compared with large-scale WWTPs, attributed to the restrained generation of CH₄ and N₂O. The PEC system activated chloride ions in sewage to generate numerous reactive chlorine species and facilitate ^•OH production, promoting contaminants removal. The PEC system exhibited operational feasibility at varying pH and total suspended solids concentrations and has outstanding reusability and stability, confirming its promising practical potential. This study proposed a novel PEC reaction for reducing operational carbon emissions from saline sewage treatment.

Recent Advancements in Photocatalysis Coupling by External Physical Fields

Photocatalysis is one of the most promising green technologies to utilize solar energy for clean energy achievement and environmental governance, such as artificial photosynthesis, water splitting, pollutants degradation, etc. Despite decades of research, the performance of photocatalysis still falls far short of the requirement of 5% solar energy conversion efficiency. Combining photocatalysis with the other physical fields has been proven to be an efficient way around this barrier which can improve the performance of photocatalysis remarkably. This review will focus on the recent advances in photocatalysis coupling by external physical fields, including Thermal-coupled photocatalysis (TCP), Mechanical-coupled photocatalysis (MCP), and Electromagnetism-coupled photocatalysis (ECP). In this paper, coupling mechanisms, materials, and applications of external physical fields are reviewed. Specifically, the promotive effect on photocatalytic activity by the external fields is highlighted. This review will provide a detailed and specific reference for photocatalysis coupling by external physical fields in a deep-going way.

Cu-Modified La2Si2O7/TiO2 composite materials: preparation, characterization and photothermal properties

Cu-Modified La₂Si₂O₇/TiO₂ composite materials were prepared by the molten salt method and a solid-phase reduction strategy. Due to the surface plasmon resonance (SPR) of copper, the optical response from the UV to the visible region and near-infrared is increased. In the meantime, it enhances the absorption of visible light by the titanium dioxide and acts as a plasma catalyst. The combination enhances the photothermal properties of the composite. The particle size of Cu/La₂Si₂O₇/TiO₂ is in the range of 100 to 230 nm. Results show that the composite has a good photothermal effect. The 1 mg ml^-1 solution can be warmed up to 63.1 °C at 0.5 W cm^-2 laser power density with a maximum temperature difference of 45 °C. It has potential applications in solar energy conversion, photothermal catalysis, etc.

Sunlight-active phytol-ZnO@TiO2 nanocomposite for photocatalytic water remediation and bacterial-fouling control in aquaculture: A comprehensive study on safety-level assessment

With a growing consciousness of the importance of nature stewardship, researchers are focusing their efforts on utilizing renewable energy, particularly solar energy, to address environmental concerns. In this context, photocatalysis has long been viewed as one of the most promising cleaning methods. Hence, we have prepared a sunlight-active phytol-assisted ZnO-TiO₂ nanocomposite (PZTN) for photocatalytic bacterial deactivation and dye degradation process. The PZTN-photocatalysis effectively deactivated the bacterial pathogens as well as malachite green dye within 240 min under direct-sunlight. Moreover, this will be the first complete study on safety level assessment of photocatalytically-remediated water through toxicity studies. The obtained results evidenced that photocatalytically-deactivated bacteria and MG-dye showed to have no toxic effects, signifying that the PZTN-photocatalyzed water seems to be extremely safe for the environment. As a result of this research, we suggest that the PZTN could be a promising sunlight-active photocatalyst for environmental water treatment. On the other hand, biofouling is a ubiquitous phenomenon in the marine environment. Bacteria are the first organisms to foul surfaces and produce biofilms on man-made submerged materials. Interestingly, PZTN-coated PVC plastic-films effectively disallowed biofilms on their surface. This part of this research suggests that PZTN coated PVC-plastics are the best alternative for biofouling management.

Efficient Electron Transfer by Plasmonic Silver in SrTiO3 for Low-Concentration Photocatalytic NO Oxidation

Photocatalysis presents a feasible option to control low-concentration NO emissions from industrial burning facilities, and increasing excitons in quantity and improving surface activity are the crucial issues to be solved. Plasmonic silver with the orientation of the (111) plane is uniformly distributed on the Ti-O termination of the SrTiO₃ (STO) (100) plane (major). The NO conversion rate has a sixfold increment compared to pristine STO. Meanwhile, the toxic NO₂ had a significant decline in the absence of water. This high performance could be attributed to the unique property of the localized surface plasmonic resonance of silver particles, which increases the optical response range of the catalyst. Meanwhile, the formation of a Schottky junction could promote the charge separation and enhance the lifetime of excitons via the electron transfer from silver particles to STO. More importantly, the Ag-O bond of the heterojunction increases the charge density of adjacent Ti, preferring to bond with the antibonding orbital electron of adsorbed molecules, which offers a favorable channel for the NO adsorption and activation of reactive oxidation species.

Strategies for preparing TiO2/CuS nanocomposites with cauliflower-like protrusions for photocatalytic water purification

A simple and controllable method was developed to prepare TiO2/CuS nanocomposites with high photocatalytic efficiency.