Separation Of Photoinduced Carriers Research Articles

Preparation and Application of a Novel S-Scheme Nanoheterojunction Photocatalyst (LaNi0.6Fe0.4O3/g-C3N4).

Rapid recombination of photogenerated electrons and holes affects the performance of a semiconductor device and limits the efficiency of photocatalytic water splitting for hydrogen production. The use of an S-scheme nanoscale heterojunction catalyst for the separation of photogenerated charge carriers is a feasible approach to achieve high-efficiency photocatalytic hydrogen evolution. Therefore, we synthesized a three-dimensional S-scheme nanoscale heterojunction catalyst (LaNi0.6Fe0.4O3/g-C3N4) and investigated its activity in photocatalytic water splitting. An analysis of the band structure (XPS, UPS, and Mott-Schottky) indicated effective interfacial charge transfer in an S-scheme nanoscale heterojunction composed of two n-type semiconductors. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy confirmed that the light-induced charge transfer followed the S-scheme mechanism. Based on the capture test (EPR) of •OH free radicals, it can be seen that the enhanced activity is attributed to the S-scheme carrier migration mechanism in heterojunction, which promotes the rapid adsorption of H+ by the abundant amino sites in g-C3N4, thus effectively generating H2. The 2D/2D LaNi0.6Fe0.4O3/g-C3N4 heterojunction has a good interface and produces a built-in electric field, improving the separation of e- and h+ while increasing the oxygen vacancy. The synergistic effect of the heterostructure and oxygen vacancy makes the photocatalyst significantly better than LaNi0.6Fe0.4O3 and g-C3N4 in visible light. The hydrogen evolution rate of the composite catalyst (LaNi0.6Fe0.4O3/g-C3N4-70 wt %) was 34.50 mmol·h-1·g-1, which was 40.6 times and 9.2 times higher than that of the catalysts (LaNiO3 and g-C3N4), respectively. After 25 h of cyclic testing, the catalyst (LaNi0.6Fe0.4O3/g-C3N4-70 wt %) composite material still exhibited excellent hydrogen evolution performance and photostability. It was confirmed that the synergistic effect between abundant active sites, enriched oxygen vacancies, and 2D/2D heterojunctions improved the photoinduced carrier separation and the light absorption efficiency of visible light. This study opens up new possibilities for the logical design of efficient photodecomposition using 2D/2D heterojunctions combined with oxygen vacancies.

C3N5/TiO2 S-scheme heterojunction film for efficient photocatalytic removal of gatifloxacin

Constructing efficient and recyclable photocatalysts is a promising method to solve antibiotic pollution. Herein, we designed and fabricated C3N5/TiO2 S-scheme heterojunction film on flexible Ti foils through the self-absorbed. The C3N5 nanosheet was tightly anchored on the TiO2 arrays with an intimate TiO2-C3N5 interface. The heterojunction exhibited an excellent photocatalytic performance and the reaction rate constant of photocatalytic degradation gatifloxacin (GAT) over C3N5/TiO2 up to 0.0252 min−1, which was 1.85 folds that of pure TiO2 arrays. The outstanding photocatalytic performance was ascribed to high-efficiency transfer and separation of photoinduced carriers and highly hydrophilic surfaces. The removal rate of GAT under different parameters suggested that the as-prepared C3N5/TiO2 has high adaptability. Moreover, the three possible GAT degradation pathways over C3N5/TiO2 were proposed based on the results of the liquid chromatograph-mass spectrometer (LC-MS) and density functional theory (DFT). Finally, a reasonable S-scheme heterojunction was proposed based on the results of experiments and DFT calculation. This work may help in designing an S-scheme heterojunction for the degradation of antibiotic pollutants.

Two-Dimensional GeC/MXY (M = Zr, Hf; X, Y = S, Se) Heterojunctions Used as Highly Efficient Overall Water-Splitting Photocatalysts.

Hydrogen generation by photocatalytic water-splitting holds great promise for addressing the serious global energy and environmental crises, and has recently received significant attention from researchers. In this work, a method of assembling GeC/MXY (M = Zr, Hf; X, Y = S, Se) heterojunctions (HJs) by combining GeC and MXY monolayers (MLs) to construct direct Z-scheme photocatalytic systems is proposed. Based on first-principles calculations, we found that all the GeC/MXY HJs are stable van der Waals (vdW) HJs with indirect bandgaps. These HJs possess small bandgaps and exhibit strong light-absorption ability across a wide range. Furthermore, the built-in electric field (BIEF) around the heterointerface can accelerate photoinduced carrier separation. More interestingly, the suitable band edges of GeC/MXY HJs ensure sufficient kinetic potential to spontaneously accomplish water redox reactions under light irradiation. Overall, the strong light-harvesting ability, wide light-absorption range, small bandgaps, large heterointerfacial BIEFs, suitable band alignments, and carrier migration paths render GeC/MXY HJs highly efficient photocatalysts for overall water decomposition.

Bidirectional heterojunctions photocatalyst engineered with separated dual reduction sites for hydrogen evolution

Photocatalytic technology is identified as one of the most clean and sustainable routes for hydrogen generation. Nonetheless, inadequate photoinduced carrier separation limits photocatalytic performance. Rationally designing bidirectional heterojunctions that leverage single/two-photon co-excitation pathways and dual reduction sites, thereby inhibiting recombination of the photoinduced carriers and exposing active sites to increase photocatalytic activity. This study proposes bidirectional heterojunctions consisting of 0D carbon dots (CDs) and nickel phthalocyanines co-modified sulfur-doped multivesicular carbon nitride tubes (denoted as 7CDs/SMVCTs/Ni0.5 %). The as-prepared photocatalyst displays a remarkable yield of 16,363.62 μmol g−1 h−1, with a rate 23.2 times that of pristine carbon nitride (denoted as PCN, 704.23 μmol g−1 h−1). The improvement of photocatalytic performance is attributed to the efficient separation and transportation of photoexcited electron-hole pairs induced by the coexistence of single/two-photon excitation pathways and dual reduction sites. The efficient combination of lateral and vertical heterostructures plays an essential role in the photocatalytic process and is exhaustively studied using catalyst rational design and modification technology.

Revealing the Enhanced Visible-light-driven Photocatalytic Activity of In2S3/CeO2 Heterojunction: Bandgap Structure Analysis and Active Radicals Determination

Background: The widespread presence of persistent organic pollutants, such as dyes in effluent from printing and textile industries, poses a significant threat to aquatic life and human health. Photocatalytic degradation is widely recognized as a promising technology to address this pollution crisis. The efficiency of photocatalysis is intricately tied to both the active radicals and the band structure of the catalyst. These factors play a crucial role in governing the photodegradation of dye molecules. Methods: In2S3/CeO2 heterojunctions were synthesized using an in-situ precipitation method and subsequently analyzed through SEM, XRD, and XPS techniques. Notably, the bandgap structure of the heterojunctions was examined through UV-Vis DRS. The photocatalytic performance of the synthesized samples was assessed by studying the degradation of methyl orange. To further validate the photocatalytic process, EPR spectroscopy was employed to confirm the presence of radicals generated within the heterojunction. Results: The heterojunction displayed a characteristic type-II structure, enhancing light absorption and facilitating the separation of photoinduced carriers. Among the In2S3/CeO2 composites, the one with a 15 wt% CeO2 content exhibited the highest photocatalytic activity, achieving an 88% degradation of methyl orange after 90 min of exposure to visible light irradiation. Additionally, •O2 − is identified as the primary active species responsible for degradation. Conclusion: UV-Vis DRS illustrated the improved transfer and separation of photogenerated electrons attributed to the optimized band structure of the heterojunction. EPR spectroscopy yielded valuable information on active radicals, thereby proposing the photocatalytic degradation mechanism.

Fabrication of stannous sulfide nanoparticles for photodegradation of thiazine derivative and evaluation of its antibacterial activity

The photocatalytic degradation of environmentally harmful chemicals has been extensively explored using a variety of photocatalysts and approaches. However, achieving efficient decomposition and removal of persistent contaminants from the aquatic environment remains a challenging factor. In this study, we report stannous sulfide nanoparticles (SnS2 NPs) prepared by a simple hydrothermal technique and characterized using various analytical methods. The prepared SnS2 NPs were used for the degradation of Methylene Blue (MB) dye under visible light irradiation, which resulted in outstanding degradation compared to other photocatalysts. According to our results, the SnS2 NPs can destroy 98.4 % of MB dye (10 ppm) in 60 minutes effectively, owing to a narrowed band energy gap and photo-induced carrier separation. Based on the results of free-radical scavenging experiment, we confirmed that hydroxyl radicals (•OH) are the key reactive species, and on this basis elucidated the possible degradation mechanism. Moreover, the SnS2 NPs photocatalyst exhibited good stability in degrading MB even after four recycles. Additionally, we analyzed the antibacterial activity of the prepared SnS2 NPs against pathogenic bacteria. As a result of this research, the proposed photocatalyst shows high potential for environmental remediation of harmful contaminants.

Fabrication of 2D/2D InVO4/BiVO4 Heterojunction with Synergistic Effects for Enhanced Photocatalytic Degradation and Photoelectrochemical Applications

In this work, we report a novel 2D/2D InVO4/BiVO4 heterojunction nanocomposite constructed through a simple hydrothermal approach. The morphological analysis demonstrated that BiVO4 nanoflakes to be anchored on the surface of InVO4 nanosheets. The InVO4/BiVO4 heterojunction nanocomposite displayed increased light absorption promoting their visible light harvesting. The photoactivity of the prepared InVO4/BiVO4 heterojunction was explored for the degradation of tetracycline (TC) under light treatment. InVO4/BiVO4 heterojunction exhibited superior photocatalytic activity than that of bare InVO4 and BiVO4. The as-prepared InVO4/BiVO4 heterojunction photoanodes achieved a higher photocurrent density of 60 μA/cm2 under illumination in 0.5 M Na2SO4 electrolyte. The enhanced photoelectrochemical performance is attributed to the synergistic effect and interface formation between InVO4 and BiVO4 and can effectively promote the charge separation and transfer of photoinduced carriers in heterojunction.

In-situ synthesis of V2AlC@V2O5/TiO2 immobilized over honeycomb support with vanadium oxide electron transfer mediator for stimulating selective CO2 photoreduction through bi-reforming in a monolith reactor

Photocatalytic CO2 reduction to valuable chemicals and fuels is a practical approach for climate action; however, available photocatalysts and photoreactors are less efficient. In this work, well-designed V2AlC@V2O5 supported TiO2 and immobilized over honeycomb support for CO2 photoreduction in a monolith reactor have been investigated. The catalysts were loaded over the monolithic support using the sol-gel dip-coating method and found promising for higher light absorbance and charge separation. The performance of V2AlC@V2O5/TiO2 composite for photocatalytic CO2 reduction with water and bi-reforming of methanol was performed using a fixed bed and monolith photoreactor. Using V2AlC@V2O5/TiO2 with a fixed bed reactor and methanol–water mixture, a CO yield of 13.75 mmol g−1h−1 was produced, 26.39 and 38.19-fold higher than using water and pristine TiO2, respectively. Similarly, CH4 production was 1.97 and 12.33 folds higher than using water and TiO2 only, whereas, using water, production of H2 was not detected. The higher photoactivity of the composite with methanol was due to efficient photo-induced carrier separation due to the synergistic effect of V2AlC/V2O5 and more production of protons. Using a monolith photoreactor, CH4, CO and H2 production rates of 55.44, 35.51 and 1.638 mmol g−1h−1 were obtained, 166.50, 2.58 and 3.05 times more than those produced using a fixed bed reactor. This significantly higher photoactivity with monolith photoreactor was due to higher photon flux utilization with surface reactions, resulting in more production and utilization of photoinduced charge carriers. The highest QY after five consecutive cycles was 48.374, 25.358 and 1.51 % for CH4, CO and H2, which is 200.5, 2.54 and 3.87 folds higher than using the fixed bed, respectively. This work provides a new approach to designing and fabricating higher efficient and stable photocatalytic system for CO2 recycling, and it can be further employed for other energy-related applications.

Photoselectively modulating main products by changing the wavelength of visible light over D-π-A-D conjugated polymers

The diversity of catalytic products determines the difficulty of selective product modulation, which usually relies on adjusting the catalyst and reaction conditions to obtain different main products selectively. Herein, we synthesized D-π-A-D conjugated organic polymers (TH-COP) using cyclotriphosphonitrile, alkyne, 2H-benzimidazole, and sulfur units as electron donors, π bridges, electron acceptors, and electron donors, respectively. TH-COP exhibited excellent photoinduced carrier separation and redox ability under different visible light wavelengths, and the main products of its CO2 reduction are CH4 (1000.0 μmol g−1) and CO (837.0 μmol g−1) under 400–420 nm and 420–560 nm, respectively. In addition, TH-COP could completely convert phenylmethyl sulfide to methyl phenyl sulfone at 400–420 nm and diphenyl disulfide at 480–485 nm in yields up to 95 %. This study presents a novel strategy for the targeted fabrication of various main products using conjugated polymers by simply changing the wavelength range of visible light.

In-situ assembling novel N-Ti3C2/BiOClxBr1−x composites with enhanced photocatalytic degradation and nitrogen reduction activity

Herein, a collection of novel N-Ti3C2/BiOClxBr1−x composites are fabricated via a simple in-situ sonochemical process. Not only the preparation method for N-Ti3C2 but also the photocatalytic system of N-Ti3C2/BiOClxBr1−x are firstly developed. Multiple characterizations jointly demonstrate the successful fabrication of the composites. Compared to that of BiOClxBr1−x, the maximum improvements of 1.16, 1.25 and 1.26 folds are severally confirmed for the photocatalytic degradation of levofloxacin, Rhodamine B, and methylene blue over N-Ti3C2/BiOClxBr1−x composites. In addition, through radicals trapping tests, the primary active species in photocatalytic degradation process are verified to be O2−. Moreover, N-Ti3C2/BiOClxBr1−x composites also exhibit 1.18 and 1.14 times enhancements for NH3 production compared with that of BiOClxBr1−x with or without the presence of methanol, respectively. In addition, the maximum improvements of photo-current and photo-potential for BiOClxBr1−x are 1.29 and 1.86 folds with the introduction of N-Ti3C2, respectively. The enhanced photocatalytic activity of N-Ti3C2/BiOClxBr1−x composites is owing to the heightened light absorption, increased specific surface area, and accelerated separation of photoinduced carriers. Additionally, the stable photocatalytic properties of N-Ti3C2/BiOClxBr1−x are confirmed by three photocatalytic recycle tests on pollutant degradation and nitrogen reduction combined with X-ray diffraction patterns before and after three recycles. This study suggests that N-Ti3C2 is an efficient ornamentation for boosting photocatalytic activity ofBiOClxBr1−x, which can also be expanded as a promising modifier for other semiconductors.

Nitrate promoted ATZ degradation in Z-scheme Cs3Bi2I9/BiVO4 photocatalytic system: Coupling ·OH and RNS mediated reduction and oxidation

Nitrate, widely present in water, can be excited by UV light and generate reactive nitrogen species (RNS) etc., facilitating pollutants selective degradation. In this work, the promoting effect of nitrate on atrazine removal in the Z-scheme Cs3Bi2I9/BiVO4 (CBI/BVO) photocatalytic system was studied. The CBI/BVO composite utilized CBI and BVO excitation to enhance photogenerated carriers production, and the Z-scheme heterojunction to increase photoinduced carriers separation yield, with a maximum value of 15.41 times that of pure BVO, releasing CBI electrons and BVO holes with powerful redox ability. Thanks to nitrate addition, the atrazine degradation improved, whose kinetic constant was 14.46 and 2.37 times higher than that of nitrate photolysis and 0.32-CBI/BVO photocatalysis. DFT, HPLC-MS, EPR, and toxicity assessments indicated the electron rich portion of atrazine and its intermediates were susceptible to RNS attack and underwent dechlorination, that combined with the oxidation brought by ·OH, synergistically promoting atrazine degradation, mineralization, and detoxification.

Template-Free Synthesis of Boron-Doped Graphitic Carbon Nitride Porous Nanotubes for Enhanced Photocatalytic Hydrogen Evolution.

The photocatalytic activity of g-C3N4 can be enhanced by improving photoinduced carrier separation and exposing sufficient reactive sites. In this study, we synthesized B-doped porous tubular g-C3N4 (BCNT) using a H3BO3-assisted supramolecular self-template method, wherein H3BO3 helped in B-doping, building a porous structure, and maintaining one-dimensional nanotubes. The tubular structure had an ultrathin tube wall and large aspect ratio, which are conducive to the directional transmission and separation of photogenerated carriers; moreover, the abundant pore structure of the tube wall could fully expose the reactive sites. The introduction of B and the cyano group modulated the bandgap of g-C3N4 and elevated the position of the conduction band, thus enhancing the photoreduction ability and effectively improving the hydrogen evolution performance. Consequently, the hydrogen evolution of BCNT-2 (220.8, 53.2 μmol·h-1) was 1.82 and 1.54 times that of ultrathin g-C3N4 nanosheets (CNN, 121.3, 34.6 μmol·h-1) under simulated sunlight and LED lamp irradiation, respectively. Thus, this work provides in-depth insights into the rational design of one-dimensional g-C3N4 nanotubes with high hydrogen evolution activity under visible irradiation.

DFT Predirected Molecular Engineering Design of Donor-Acceptor Structured g-C3N4 for Efficient Photocatalytic Tetracycline Abatement.

The photocatalytic environmental decontamination ability of carbon nitride (g-C3N4, CN) typically suffers from their inherent structural defects, causing rapid recombination of photogenerated carriers. Conjugating CN with tailored donor-acceptor (D-A) units to counteract this problem through electronic restructuring becomes a feasible strategy, where confirmation by density functional theory (DFT) calculations becomes indispensable. Herein, DFT is employed to predirect the copolymerization modification of CN by benzene derivatives, screening benzaldehyde as the optimal electron-donating candidate for the construction of reoriented intramolecular charge transfer path. Experimental characterization and testing corroborate the formation of a narrowed bandgap as well as high photoinduced carrier separation. Consequently, the optimal BzCN-2 exhibited superior photocatalytic capacity in application for tetracycline hydrochloride degradation, with 3.73 times higher than that of CN. Besides, the BzCN-2-based photocatalytic system is determined to have a toxicity-mitigating effect on TC removal via T.E.S.T and prefers the removal of dissociable TC2- species under partial alkalinity. This work provides insight into DFT guidance for the design of D-A conjugated polymer and its application scenarios in photocatalytic decontamination.

Electronic metal-support interaction-induced space charge polarization for boosting photoelectrochemical water splitting

Overcoming the inherent transportation of charge constraint of the photoanode has been critical for seeking feasible photoelectrochemical (PEC) water splitting. Here, we propose to utilize electron metal-support interactions (EMSI) between Cu nanoparticles (NPs) and N-C support for modifying the electronic structure of CuNPs-N-C/SnS2 photoanode and analyze the impact of EMSI on the process of PEC water splitting. The combination of detailed theoretical simulation calculations and comprehensive characterizations indicates that the charge imbalance induced by EMSI within the CuNPs-N-C and SnS2 interfaces results in an enhanced interfacial polarized electric field and boosts the separation of photo-induced carriers at the CuNPs-N-C and SnS2 interfaces. The optimal CuNPs-N-C/SnS2 photoanode displays remarkable properties with a considerably upgraded photocurrent of 2.33 mA cm−2 at 1.23 VRHE, which is 6.30 beyond the value of SnS2 (0.37 mA cm−2). This work paves a way to developing high-performance photoanodes for efficient PEC water splitting.

Enhanced Spin-Polarized Electric Field Modulating p-Band Center on Ni-Doped CdS for Boosting Photocatalytic Hydrogen Evolution.

It is a challenge to regulate charge separation dynamics and redox reaction kinetics at the atomic level to synergistically boost photocatalytic hydrogen (H2) evolution. Herein, a robust Ni-doped CdS (Ni-CdS) photocatalyst is synthesized by incorporating highly dispersed Ni atoms into the CdS lattice in substitution for Cd atoms. Combined characterizations with theoretical analysis indicate that local lattice distortion and S-vacancy of Ni-CdS induced by Ni incorporation lead to an increased dipole moment and enhanced spin-polarized electric field, which promotes the separation and transfer of photoinduced carriers. In this contribution, charge redistribution caused by enhanced internal electric field results in the downshift of the S p-band center, which is conducive to the desorption of intermediate H* for boosting the H2 evolution reaction. Accordingly, the Ni-CdS photocatalyst shows a remarkably improved photocatalytic performance with an H2 evolution rate of 20.28mmolg-1h-1 under visible-light irradiation, which is 5.58 times higher than that of pristine CdS. This work supplied an insightful understanding that the enhanced polarization electric field governs the p-band center for efficient photocatalytic H2 evolution activity.

Grinding preparation of 2D/2D g-C3N4/BiOCl with oxygen vacancy heterostructure for improved visible-light-driven photocatalysis

A novel 2D/2D g-C3N4/BiOCl (CN/BOC) heterojunction photocatalyst was synthesized by grinding appropriate amounts of CN, Bi(NO3)3·5H2O, glacial acetic acid and KCl at room temperature. The porous CN nanosheets not only facilitate the in situ nucleation and growth of BOC to form thin nanosheets and constitute an intimate contact interface, but also introduce more oxygen vacancies (OVs) in the grinding process. The 2D/2D CN/BOC heterojunction had a good interface and generates a built-in electric field, which can improve the separation of e− and h+. The synergistic effect of the heterostructure and OVs made the photocatalyst have significantly better performance than CN and BOC alone under visible light. The most efficient CN/BOC-5 could achieve a tetracycline (TC) degradation rate of 89.8% within 2 h, which was 1.9 and 1.2 times faster than CN and BOC, respectively. It catalyzed the reduction of CO2 to CO at a rate of 2.00 μ mol h−1 g−1, 1.1 and 3.2 times faster than CN and BOC, respectively. The mechanism for the photocatalysis of CN/BOC-5 was revealed. It was confirmed that the efficiency of photo-induced carrier separation and visible-light photo-absorption were both considerably increased by the synergistic interaction between OVs and 2D/2D heterojunction. This research may open up new possibilities for the logical design of efficient photocatalysts through combining 2D/2D heterojunctions with OVs for environmental remediation.Graphical

PdCu alloy anchored defective titania for photocatalytic conversion of carbon dioxide into methane with 100% selectivity

The photoreduction of CO2 into CH4 with simultaneous high activity and selectivity is a promising strategy to increase energy supply and alleviate global warming. However, the absence of the active sites that is responsible for the adsorption and activation of CO2 and the generation of CO and H2 via side reactions often lead to poor efficiency and low selectivity of the catalyst. Herein, Cu, Pd, and PdCu metal clusters cocatalyst-anchored defective TiO2 nanotubes (Cu/TiO2-SBO, Pd/TiO2-SBO, and Pd1Cu1/TiO2-SBO) were designed via a simple solution impregnation reduction and applied for photocatalytic conversion of CO2 to CH4. The Pd1Cu1/TiO2-SBO photocatalyst exhibits excellent catalytic performance among the other catalysts for photoreduction of CO2 into CH4. More interestingly, the product selectivity of CH4 reaches up to 100% with a rate of 25 µmol g−1 h−1. In-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) simulations indicate that the main reasons for the high selectivity of CH4 are attributed to the PdCu alloy and oxygen vacancies, which jointly enhance the photoinduced carrier separation and lower energy barriers of key intermediates. Moreover, due to the tunable d-band center of the Cu site in the PdCu alloy, the generated intermediates can be well prevented from poisoning and promoted to participate in further reactions. Hopefully, the current study will provide insight into the development of new, highly selective photocatalysts for the visible light-catalytic reduction of CO2 into CH4.

In-situ construction of Z-scheme 2D/2D g-C3N4/BiOBr heterojunction with enhanced photocatalytic CO2 reduction

A novel series of g-C3N4/BiOBr (CN/BOB) Z-scheme heterojunction catalysts with two-dimensional/two-dimensional (2D/2D) morphology were synthesized by an in-situ hydrolysis method for photocatalytic CO2 reduction. Without adding any sacrificial agents or co-catalysts, the optimal CN/BOB heterostructure exhibits a boosted CO generation rate of 20.1 μmol·g-1·h-1 under the simulated solar light irradiation, severally being 1.7 and 3.7 times that of pristine BiOBr and g-C3N4. The enhanced performance principally benefit from the 2D/2D microstructure and Z-scheme heterojunction of photocatalysts. The intimate contact of 2D/2D morphology signifies more transmission channels and shorter transfer interface distance of photogenerated charges. While relevant characterizations and first-principles calculations jointly demonstrate that the Z-scheme heterojunction could significantly accelerate the spatial separation and transfer of photo-induced carriers, and evidently promote the redox ability of photocatalysts. The research furnishes a novel strategy to construct a promising bismuth oxyhalide based heterojunction catalyst for the application of photocatalytic CO2 reduction.

NiCS3: A cocatalyst surpassing Pt for photocatalytic hydrogen production

Cocatalysts play a key role in improving photocatalytic performance by enhancing conductivity and providing an enormous number of active sites simultaneously. However, cocatalysts are usually made of noble metals such as Pt, which are expensive and rare. Therefore, cocatalysts derived from cheap and abundant elements are highly desirable. Here, for the first time, we demonstrate that NiCS3, which is made from nickel that is abundant and costs less than 0.04 % of Pt, is an effective substitute for Pt cocatalysts for the photocatalytic activity of CdS nanorods in hydrogen evolution reaction (HER). Under visible light, the NiCS3/CdS composite with NiCS3 as the cocatalyst achieved an astonishing H2 production of 61.9 mmol·g−1·h−1 while maintaining high stability, which is 14 times higher than that observed when using CdS alone and nearly 2 times higher than that of Pt/CdS. We also established that the metallicity of NiCS3 results in good carrier conductivity, which promotes the electron transfer and the separation of photo-induced carriers. Due to the appropriate adsorption energy ΔGH*, NiCS3 more readily adsorbs hydrogen protons and desorbs molecular hydrogen during the photocatalytic process compared with Pt. Additionally, NiCS3 can effectively inhibit the photo-corrosion effect of CdS itself, ensuring a good stability of HER. These results suggest that NiCS3 is a promising substitute for Pt cocatalysts.

Efficient liquid phase photothermal catalysis realized by Ag2O/Bi4O5I2via heat-localization in a microreactor.

By constructing a Ag2O/Bi4O5I2 p-n heterojunction and applying a heat-localization microreactor, efficient photocatalysis enhanced by both photoinduced carrier separation and the photothermal effect was realized. This work focuses on the utilization of near-infrared light to broaden the absorption spectrum and accelerate the transportation of carriers. Through the production and localization of heat, it provides a novel thought for full-spectrum photocatalysis.