Accelerated Charge Separation Research Articles

Oxygen vacancies-tuned BiOBr nanosheets for accelerating CO2 and Cr(VI) photoreduction

Unsatisfactory charge separation ability and insufficient active sites are the main factors leading to low efficiency for photocatalytic CO2 conversion and Cr(VI) reduction. Constructing surface defects to accelerate charge separation is an effective strategy for promoting photocatalytic process. Herein, the oxygen vacancies modulated BiOBr nanosheets were constructed by NaBH4 solution treatment. Density functional theory calculation results found that the formed oxygen vacancies would increase the electron density around Bi atoms near the oxygen vacancies, and inhibiting recombination of the photoinduced carriers. Besides, abundant oxygen vacancies can effectively enhance the adsorption of CO2 molecules. Therefore, the BiOBr with rich oxygen vacancies (BiOBr-ROV) shows higher evolution rates for CO (15.66 μmol g−1) and CH4 (0.22 μmol g−1) under irradiation of 300 W Xe lamp for 4 h compared with pristine BiOBr nanosheets (BiOBr) and BiOBr with deficient oxygen vacancies (BiOBr-DOV). The intermediate products in the CO2 reduction process have been detected by in-situ Fourier-transform infrared spectroscopy. Besides, the photodegradation activity of Cr(VI) over BiOBr-ROV is 98.65% under 80 min of irradiation, which is higher than that of BiOBr (78.01%) and BiOBr-DOV (53.67%). The work provides a new possibility to construct photocatalysts with high-performance for solar energy conversion.

Coordination engineering of the interfacial chemical bond and sulfur vacancies modulated S‐scheme charge transfer for efficient photocatalytic CO2 reduction

Surface charge localization and poor carrier separation efficiency limited the of photocatalytic CO2 reduction (PCR) activity. Creating heterojunctions between the interfacial layers was an important strategy used to enhance catalytic activity. Here, a core-shell structure S-scheme catalyst was constructed by growing of Bi2WO6 (BWO) nanospheres on the surface of Zn0.5Cd0.5S(VS-ZCS) nanospheres with abundant sulfur defect, and which was coordinated by the interface bonding and the sulfur vacancies (VS) for efficient PCR. Meanwhile, the surface potential was 91 mV, indicating the creation of strong interface electric field (IEF). As part of the strong synergy of the Bi-S bond, IEF and VS, the improved photocatalyst exhibited high CO evolution rate of 86.16 μmol⋅g−1, which was about 9.23 fold of the pristine VS-ZCS. This was attributed to production of *COOH intermediates on the VS-ZCS/BWO surface that had been proved to be crucial for PCR generation CO. Besides, electrons quickly migrated through the formed Bi-S bonds to the catalytic sites, accelerating charge separation. The use of VS as electron traps was beneficial for regulating the localization of photogenerated charges on the surface of S-scheme heterostructure. The Bi-S bonds and VS modulated S‐scheme charge transfer for efficient photocatalytic CO2 reduction provides new insights into photocatalytic CO2 reduction.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation.

The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation-decomposition (NID) strategy that is effective in peeling off BCN into few-layer C3N4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g-1 h-1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on-site formed H2O2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2 % and record-high production rate of 1893 μmol g-1 h-1 among the metal-free C3N4-based photocatalysts.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation

AbstractThe exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts.

Accelerating Charge Separation and CO2 Photoreduction in Aqueous Phase under Visible Light with Ru Nanoparticles Loaded on Ga-Doped NiTiO3 in a Batch Photoreactor.

Titanate perovskite (ATiO3) semiconductors show prospects of being active photocatalysts in the conversion of CO2 to chemical fuels such as methanol (CH3OH) in the aqueous phase. Some of the challenges in using ATiO3 are limited light-harvesting capability, rapid bulk charge recombination, and the low density of catalytic sites participating in CO2 reduction. To address these challenges, Ga-doped NiTiO3 (GNTO) photocatalysts in which Ga ions substitute for Ti ions in the crystal lattice to form electron trap states and oxygen vacancies have been synthesized in this work. The synthesized GNTO was then loaded with Ru nanoparticles to accelerate charge separation and enable excellent CO2 photoreduction activity under visible light. CO2 photoreduction was conducted in a batch photoreactor charged with a 0.1 M NaHCO3 aqueous solution at room temperature and a 3.5 bar pressure using a 1.0 wt % Ru-GNTO photocatalyst to yield methanol at a rate of 84.45 μmol g-1 h-1. A small amount of methane was produced as a side product at 21.35 μmol g-1 h-1, which is also a fuel molecule. We attribute this high catalytic activity toward CO2 photoreduction to a synergistic combination of our novel heterostructured 1.0 wt % Ru-GNTO photocatalyst and the implementation of a pressurized photoreactor. This work demonstrates an effective strategy for metal doping with active nanospecies functionality to improve the performance of ATiO3 photocatalysts in valorizing CO2 to solar fuels.

Enhanced photocatalytic activity of BiOCl/BiOBr/SnS2 heterojunction using a superfine SnS2 and double S-scheme

Photocatalysis is a green approach to solving energy and environmental problems, and researchers are still pursuing high-performance photocatalysts. Although BiOX (X = Cl or Br) has a suitable bandgap and good stability, its photoresponse is mostly concentrated in the UV region. Conversely, SnS2 has a wide photoresponse range but exhibits perceptible photocorrosion and poor stability. To exploit the advantages of both BiOX and SnS2, this study hydrothermally synthesized and introduced superfine SnS2 (∼30 nm in size) into a BiOCl/BiOBr binary system to fabricate BiOCl/BiOBr/SnS2 composites. Subsequently, the degradation performance of these composites in a Rhodamine B solution under visible light was investigated. Results show that the BiOCl/BiOBr/SnS2 heterojunctions were successfully prepared and the composites exhibited the best photocatalytic performance with 6% mass fraction of SnS2 (BiOCl-to-BiOBr mol ratio = 1:1). The formation of a double S-schedule heterojunction between BiOCl/BiOBr and SnS2 not only accelerated charge separation and transfer but also broadened the photoresponse range and reduced photoelectron–hole recombination under full-spectrum irradiation. Loading a small narrow-bandgap photocatalyst onto a large photocatalyst provides an effective way to construct heterojunctions with excellent photocatalytic performance. The ternary photocatalyst presents a favorable photocatalytic stability, and its photodegradation rate is 4.6, 4.5 and 220.5 times that of BiOCl, BiOBr and SnS2, respectively.

Revealing the impact of different precursors and solvents for supramolecular complex formation and in-situ C-doping in g-C3N4 with enhanced photocatalytic H2O2 production

The reinforced light-harvesting capability suppresses photocarrier recombination and increases the specific surface area, representing the possibility of excellent photocatalytic performance for graphitic carbon nitride (CN) photocatalysts. Herein, the remarkable photocatalytic properties of porous carbon-doped g-C3N4 (CCN) were enhanced through the incorporation of a supramolecular complex, M-CA-U (melamine-cyanuric acid-urea), in DMSO as the carbon dopant source. Through the diverse characterization methods, the successful formation of the supramolecular g-C3N4 using varying polarity of solvent was verified, achieved through a simple hydrothermal/solvothermal process. The CCN-MCAU-DMSO photocatalyst achieved the maximum photocatalytic H2O2 production rate, 1.3-fold higher than other prepared samples. The outstanding performances of CCN-MCAU-DMSO were probably attributed to the extended specific surface area, robust visible light response, adjusted electronic band structure, accelerated charge separation, and limited charge recombination. The photocurrent response and photoluminescence spectroscopy analysis confirmed excellent charge carriers and separation. Overall, this work provided a new idea to design and construct high-efficiency porous supramolecular assembly of CCN photocatalysts for photocatalytic studies.

Oxygen vacancies generation in CeO2 via Y/Nd co-doping with accelerated charge separation by decorating on rGO sheets for sunlight-driven photodegradation of hazardous dyes

In the present study, Y/Nd co-doped CeO2 (CeYNdO2) nanoparticles and rGO-supported CeYNdO2/rGO nanocomposite were synthesized via sol-gel route. The obtained nanocomposite has outstanding redox features, highlighting a large surface area, excellent light-capturing response, abundant oxygen vacancies, remarkable photodestruction performance, and promising stability compared with CeYNdO2 nanoparticles. Especially, using the optimal condition, the photodestruction efficiencies of MB, SO, and EY reached up to 99.2 %, 71.8 %, and 99.7 % only in 60 min of irradiation for CeYNdO2/rGO nanocomposite, respectively. The several influencing parameters including catalyst dose, dye amount, pH variation, and main reactive radicals were tested to evaluate the CeYNdO2/rGO nanocomposite performance. The stability of the CeYNdO2/rGO nanocomposite was also tested for the repetitive 6th cycles. Moreover, the probable photodestruction pathways, and reasonably boosted performance were thoroughly investigated given in Scheme- 1. The obtained results highlight that the Y/Nd doping and rGO synergy is promising for environmental remediation, and propose a reasonable low-cost strategy to modify the performance of CeO2-based composite materials, especially in photodestruction of toxic dyes.

Key Strategies on Cu2O Photocathodes toward Practical Photoelectrochemical Water Splitting.

Cuprous oxide (Cu2O) has been intensively in the limelight as a promising photocathode material for photoelectrochemical (PEC) water splitting. The state-of-the-art Cu2O photocathode consists of a back contact layer for transporting the holes, an overlayer for accelerating charge separation, a protection layer for prohibiting the photocorrosion, and a hydrogen evolution reaction (HER) catalyst for reducing the overpotential of HER, as well as a Cu2O layer for absorbing sunlight. In this review, the fundamentals and recent research progress on these components of efficient and durable Cu2O photocathodes are analyzed in detail. Furthermore, key strategies on the development of Cu2O photocathodes for the practical PEC water-splitting system are suggested. It provides the specific guidelines on the future research direction for the practical application of a PEC water-splitting system based on Cu2O photocathodes.

Super-strong Zn and S atomic terminals in an organic/inorganic hybrid S-scheme polyimide based heterojunction for efficient photocatalytic treatment of mixed pollutant wastewater

Integrated oxidation and reduction reactions in the field of wastewater treatment with mixed high concentrations of sewage achieved by photocatalysis are highly desirable but still challenging. The construction of the S-scheme heterojunction system is expected to be a promising strategy to provide carriers with strong redox ability for oxidation of oxytetracycline hydrochloride (OTC) with simultaneous reduction of hexavalent chromium (Cr(VI)). Reduced graphene oxide (rGO) and ZnIn2S4 (ZIS) were successively assembled on perylene diimide polymer (PDIP) nanorods to form the S-scheme ZIS/rGO/PDIP heterojunction. The construction of organic–inorganic systems achieves wide light absorption, enhanced exciton dissociation and accelerated charge separation. A non-radiation-quenched electron transport path is formed in the ZIS/rGO/PDIP system from the conduction band of PDIP through rGO to the valence band of ZIS. The electronic energy state of the S-scheme ZIS/rGO/PDIP heterojunction was changed, and the Zn and S atomic terminals can realize strong adsorption of OTC and Cr(VI).

Piezoelectric polarization accelerated charge separation in Zinc stannate based Schottky barrier for high-efficiency hydrogen evolution

Piezoelectric polarization can effectively improve the separation and transfer of the carriers in photocatalyst. Herein, a dimension-matched piezo-photocatalyst was designed based on plate-like orthorhombic perovskite Zinc stannate (ZnSnO3)@reduced graphene oxide (rGO), which verified the prominent hydrogen (H2) evolution performance. Driven by the mechanical vibration induced piezoelectric field, the limitation of photocatalytic H2 evolution on the proper band edge position had been breached. The band of ZnSnO3 could be tilted more negative than H2O/H2 redox potential under the piezoelectric field, making it possible to achieve H2 evolution which was originally unsatisfactory. Moreover, on the basis of piezoelectric field, the Schottky barriers established in the catalyst further accelerated the electron separation. The electron paramagnetic resonance results demonstrated that the strongest ·O2− and ·OH radical intensities could only be observed when under the synergistic of light and ultrasonic. The effect of contents, size, surface chemistry of rGO and the ultrasonic power on piezo-photocatalytic performance were also optimized. Satisfactory, the ZnSnO3@rGO exhibited superior piezo-photocatalytic H2 evolution (5.66 mmol g−1), which was four times more than that of ZnSnO3 (1.37 mmol g−1). This work sheds light on the essentially synergistic effect of the mechanical and luminous energy in H2 evolution through piezo-phototronic process.

Dual function of magnetic field in enhancing antibiotic wastewater treatment by an integrated photocatalysis and fluidized bed biofilm reactor (FBBR)

The integrated photocatalysis and fluidized bed biofilm reactor (FBBR) is an attractive wastewater treatment technique for managing wastewater containing antibiotics. However, the fast recombination of photoinduced charge and low microbial activity limit the degradation and mineralization efficiency for antibiotics. To address this, we attempt to introduce magnetic field (MF) to the integrated system with B-doped Bi3O4Cl as the photocatalysts to effectively improve removal and mineralization of ciprofloxacin (CIP). As a consequence, the degradation rate reaches 96% after 40 d in integrated system with MF. The biofilm inside the integrated system with MF carrier can mineralize the photocatalytic products, thereby increasing the total organic carbon (TOC) degradation rate by more than 32%. The electrochemical experiment indicates the Lorentz force generated by MF can accelerate charge separation, increasing the electron concentration. Simultaneously, the increased amounts of electrons lead to the generation of more ·OH and ·O2−. MF addition also results in increased biomass, increased biological respiratory activity, microbial community evolution and accelerated microbial metabolism, enabling more members to biodegrade photocatalytic intermediates. Therefore, applied MF is an efficient method to enhance CIP degradation and mineralization by the integrated system.

Sulfur vacancies promoted highly efficient visible light photocatalytic degradation of antibiotic and phenolic pollutants over WS2/rGO heterostructure

Antibiotic and phenolic contaminations are severe and have become a significant source of worry in recent years. A multifunctional sulfur vacancy-induced WS2/rGO heterostructure was fabricated by a simple hydrothermal process for the photocatalytic degradation of antibiotic and phenolic compounds. The sulfur-based defects can reduce bandgap energies and enhance visible light absorption. The sulfur-enriched WS2/rGO heterostructure exhibited efficient photocatalytic activity towards Ciprofloxacin (CIP) and 4-Nitrophenol (4-NP) degradation under visible light illumination, and the deceptive rate constant is about 13 and 22 times higher than pristine WS2, and the removal efficiency was 16 and 13 times higher than pristine GO catalysts. The degradation efficiency and kinetic rate constants of 4-NP and CIP were 96.95 %, 92.30 %, and 0.113 min−1, 0.027 min−1, respectively. The excellent photocatalytic activity of WS2/rGO heterostructure was due to rGO acts as an electron mediator, and helps to accelerate charge separation and reduce the recombination rates. In addition, rGO improved the surface appearance of the heterostructure and provided more adsorption and reaction sites. The photocurrent measurement and time-resolved spectrum were used to investigate the photogenerated charge separation. Furthermore, the superoxide radical was the dominant reactive species of 4-NP and CIP degradation, as demonstrated by electron spin resonance and scavenger experiments. The possible degradation pathway and mechanism of 4-NP were proposed using liquid chromatography-mass spectroscopy.

How the π bridge in donor-π-acceptor type covalent triazine frameworks influenced their photocatalytic hydrogen evolution performance

Covalent triazine frameworks (CTFs) have recently emerged as promising organic semiconductor materials for use in hydrogen evolution reactions (HERs) under visible light radiations. Nevertheless, how to favorably tune the CTF structure and optimize the photo-induced electron transfer pathway for highly efficient HERs still remains a challenge. Herein, we designed a thiophene-bridged electron-donating triphenylamine moiety-based donor-π-acceptor (D-π-A) type CTF, SCTF, which is found to be a more feasible photocatalyst for HER in comparison with the benzene-bridged one, BCTF. The HER rate by using SCTF could reach 977.1 μmol h−1, which is 6.81 times that by BCTF. Further studies on the thermodynamics and kinetics of charge separation in resulted CTFs suggested that the employment of thiophene π bridge in SCTF rather than benzene in BCTF could lead to the broader light absorption, optimize charge transfer pathway in crystalline CTFs and enhance the built-in electric field to dramatically accelerate charge separation and transfer. The in-depth exploration of the photocatalytic process has further revealed the role of thiophene bridge in promoting the photocatalytic HER efficiency for D-π-A type CTFs. Overall, we have offered a promising strategy to finely tune CTF structure and the photogenerated carriers transfer pathway for efficient CTF-based photocatalytic HER catalysts.

Visible-light induced tetracycline degradation catalyzed by dual Z-scheme InVO4/CuBi2O4/BiVO4 composites: The roles of oxygen vacancies and interfacial chemical bonds

Dual Z-scheme InVO4/CuBi2O4/BiVO4 (CuInBi) composites with rich oxygen vacancies and chemical bonds at the heterojunction interfaces were fabricated, for the first time, through hydrothermal method with post annealing treatment, in which CuBi2O4 acts as a bridge to connect InVO4 and BiVO4. The as-prepared composites exhibited superior photocatalytic activity compared with the individual semiconductors. Specifically, the degradation rate of tetracycline (20 mg/L) in the presence of CuInBi-1 (1.0 g/L) was up to 5.4, 2.8, and 3.1 times faster than those in the presence of CuBi2O4, InVO4, and BiVO4, respectively. The enhanced photocatalytic performance could be partially attributed to the good light absorption of CuBi2O4, which broadens the visible light response of the InVO4/CuBi2O4/BiVO4 composites. Meanwhile, the interfacial chemical bonds in the dual Z-scheme heterojunction help accelerate charge separation and maintain strong redox activity. In addition, the oxygen vacancies, induced mainly by the low-valent vanadium atoms, facilitate the production of singlet oxygen (1O2) through energy transfer, which easily attacks the electron-rich groups, including phenolic group, dimethylamino group, amine group, and double bonds, in tetracycline. The InVO4/CuBi2O4/BiVO4 composite exhibited excellent reusability and stability, and performed well in photocatalytic degradation of tetracycline in river water and under natural sunlight, demonstrating great potential for practical application. The probable photocatalytic mechanism of InVO4/CuBi2O4/BiVO4 composite was proposed according to the results of density functional theory (DFT) calculations, and the reactive oxygen species (ROSs) and major degradation intermediates detected in the photocatalytic system. This work demonstrates the important roles of oxygen vacancies and interfacial chemical bonds in boosting the photocatalytic activity of Z-scheme heterojunctions and provides a reference for the construction of high-activity photocatalysts for efficient degradation of antibiotics.

Effect of perylene assembly shapes on photoelectrochemical properties and ultrasensitive biosensing behaviors toward dopamine.

In this study, a photoelectrochemical (PEC) sensor based on perylene diimide derivatives (PDIs) was developed for the ultrasensitive quantification of dopamine (DA). PDIs were able to form self-assembled semiconductor nanostructures by strong π-π stacking, suitable for photoactive substances. Moreover, the shape of the PDI significantly affected the PEC properties of these nanostructures. The results showed that amino PDI with two-dimensional (2D) wrinkled layered nanostructures exhibited superior PEC properties relative to one-dimensional (1D) nanorods and fiber-based nanostructures (methyl and carboxyl PDIs). Based on these results, a mechanism for PEC sensor action was then proposed. The presence of 2D amino-PDI resulted in accelerated charge separation and transport. Furthermore, dopamine acted as effective electron donor to cause an increase in photocurrent. The as-obtained sensor was then used to detect small molecules like DA. A blue light optimized sensor at an applied potential of 0.7V showed a detection limit of 1.67nM with a wide linear range of 5nM to 10μM. On the other hand, the sensor presented acceptable reliability in determining DA in real samples. A recovery rate between 97.99 and 101.0% was obtained. Overall, controlling the morphology of semiconductors can influence PEC performance, which is a useful finding for the future development of PEC sensors.

Engineering D-A polymer polarity in heterostructure photocatalyst for improved interfacial charge transfer efficiency

Conventional inorganic semiconducting photocatalysts are facing insufficient light harvesting as well as severe charge recombination problems. Constructing heterostructures is a well-known strategy for accelerating charge separation, especially when hybridizing with donor–acceptor (D-A) conjugated polymers, which features tunable bandgap and high absorption coefficient, these problems can be simultaneously eased. However, the singlet exciton binding energy of D-A polymers is too high for efficient exciton dissociation. In this work, we designed fluorine substituted D-A polymer PxF-T (x = 1, 2, 4) and studied polarity effect on the interfacial charge transfer in CdS/PxF-T. By adjusting the numbers of F substitutions in the acceptor unit, the electron-withdrawing ability of A site can be improved while the polarity of the whole organic molecules is tuned. Among 1, 2, 4 substitutions, the photocatalytic hydrogen production results show that the single F substitution induces the most efficient hydrogen production activity of 6327.7 μmol·g−1·h−1, which is 30.1 times higher than that of pristine CdS. In addition, electrochemical test and time-resolved transient absorption study further confirmed the improved charge transfer activity. Density functional theory calculations reveal that the F introduction induced polarity change is responsible for the improved interfacial charge transfer efficiency, however the increased number of substitutions is not necessarily favorable for improved polarity. This work uncovers the effect of fluorine substitution on the intramolecular polarity of D-A semiconductor for the fabrication of efficient hybrid photocatalysts.

Peroxymonosulfate‐Assisted Phenol Degradation via a Magnetic Covalent‐Triazine‐Framework‐Based Photocatalyst

AbstractThe development of efficient heterostructures combining covalent organic frameworks (COFs) and ideal semiconductors can significantly improve photocatalytic performance for pollutant degradation. Herein, we present the design, synthesis, and characterization of a core‐shell‐structured nanocomposite comprising covalent triazine framework‐encased Fe3O4 magnetic particles employed as a heterojunction photocatalyst for activating peroxymonosulfate (PMS) in phenol degradation. The distinctive internal structure between the TpMa shell (Tp=2,4,6‐trihydroxy‐1,3,5‐benzenetricarboxaldehyde, Ma=melamine) and the Fe3O4 core (Fe3O4@TpMa) facilitated charge transfer and accelerated charge separation. Furthermore, PMS served as an electron acceptor, enhancing photogenerated charge separation and maximizing the production of reactive oxygen species. The Fe3O4@TpMa/PMS system demonstrated remarkable photocatalytic performance and stability, achieving complete phenol degradation (10 mg L−1) in 40 min. The exceptional photocatalytic activity resulted from the synergistic effect of ⋅OH, SO4⋅−, O2⋅−, 1O2, and h+ generated in the Fe3O4@TpMa/PMS system during the degradation process. Overall, this material offers excellent potential for solar‐driven pollutant degradation and enables the development of COF‐based materials for wastewater treatment applications.

Synergistic effects of cocatalyst and homojunction/heterojunction with boosted photocatalytic H2 evolution over Zn0.5Cd0.5S/NDs

For improved photocatalytic hydrogen evolution, building heterojunction structures has been considered as a promising strategy to promote charge separation and transportation. Herein, an in-situ hydrothermal process was used to prepare the novel twin Zn0.5Cd0.5S/NDs (ZCND-x) homojunction/heterojunction photocatalyst of nanodiamonds (NDs) dots anchored twin Zn0.5Cd0.5S (T-ZCS). Among all the composites, the ZCND-10 hybrid exhibits a much higher H2 performance of 160.035 mmol/g/h with a mixture of Na2S and Na2SO3 (pH = 13.82) as hole eliminator agent, which is considerably 5.3 times that of pure T-ZCS nanoparticles. Furthermore, the optimum apparent quantum yield (AQY) of ZCND-10 is up to 32.42% at λ = 420 ± 15 nm. At the same time, ZNCD-10 heterojunction owns excellent H2 evolution cycle activity and photostability. Simultaneously, photocatalyst depicts good photocatalytic overall water splitting performance. Meanwhile, experimental characterization results indicate extend light response, high surface area, as well as accelerate charge separation of homojunction/heterojunction induced phase junctions by the interfacial synergistic effect between T-ZCS and NDs, endowed with excellent H2 evolution performance and chemical stability. Theoretical work functions, electron density distribution and in-situ XPS further clarify the electron transfer pathway between T-ZCS and NDs. The potential mechanism of photocatalytic enhancement of ZCND-x hybrid is proposed, which may lead to a new thinking for the efficient preparation of other photocatalytic materials.

Engineering single Pt Atoms on hybrid amorphous/crystalline CoFe layered double hydroxide accelerates the charge transfer for solar water splitting

Owing to the sluggish kinetics suppressing the oxygen evolution reaction, developing single atoms (SAs) catalyst oxygen evolution reaction catalysts on photoelectrodes is challenging for accelerating charge separation and transfer on photoelectrochemical water splitting. Herein, we elaborately demonstrate the decoration of platinum SAs on hybrid crystalline/amorphous CoFe LDH, and assess the role of SAs on the photogenerated charge carrier separation and transport of photoelectrode. The crystalline/amorphous CoFe LDH is capable of embedding the platinum SAs in its structure by modulating the electronic structure. The single atoms platinum in catalyst enables the effective charge transfer and suppress the charge recombination of the BiVO4 photoelectrode. The SAs Pt/AC-CoFe catalyst delivers an overpotential of 230 mV at 10 mA cm−2, obviously lower than those of AC-CoFe without the introduction of SAs Pt. The SAs Pt/AC-CoFe/BiVO4 exhibits an excellent PEC performance, a current density of 5.14 mA cm−1 obtained at 1.23 VRHE in 1 M KBi under one sun illumination with a stability of 20 h. This work proposes a rational design of single atoms catalysts decorated on semiconductors and reveals the potential of the single atoms to boost charge carrier kinetics.