Separation Of Holes Research Articles

Inorganic/organic hybrid interfacial internal electric field modulated charge separation of resorcinol-formaldehyde resin for boosting photocatalytic H2O2 production

The strategy of inorganic/organic semiconductor material hybridization is of great significance for the development of highly active photocatalysts. Resorcinol-formaldehyde (RF) resin with a special donor-acceptor (D-A) structure shows excellent performance in the photocatalytic production of H2O2. However, the lack of an internal driving force for the separation and transfer of photogenerated electrons and holes in RF resin greatly limits the performance of H2O2 production. Herein, an inorganic/organic hybrid core-shell structure ZnS@RF photocatalyst was prepared by directionally induced coating of RF resin shells of different thicknesses on the surface of monodisperse ZnS nanospheres. Consequently, the photocatalytic H2O2 performance of ZnS@RF with the optimal RF resin shell thickness reaches 367.9 μmol L−1, which is 69 and 2 times that of ZnS and HRF, respectively. Density functional theory (DFT) calculations and related characterization results collectively demonstrate that the excellent photocatalytic H2O2 production performance of ZnS@RF photocatalyst is mainly attributed to the internal electric field (IEF) formed at the hybrid interface of ZnS and RF heterojunction and the optimization of RF shell thickness, which significantly enhances the separation and transfer of photogenerated carriers and modulates the interfacial catalytic reaction kinetics. This work opens up an avenue for designing inorganic/organic hybrid heterojunction photocatalyst materials with excellent photocatalytic activity.

Cu-based composite materials derived from MOFs for visible light PMS activation in tetracycline removal

The degradation of recalcitrant antibiotics through the activation of peroxymonosulfate (PMS) is an important branch of advanced oxidation processes (AOPs), with widespread attention given to the application of metal-organic frameworks (MOFs) in this field. The article successfully synthesized CuxO/N-doped carbon/Cu-MOF (CuxO/NC/Cu-MOF) nanocomposites by low-temperature thermal treatment of Cu-MOF precursors. Compared with the original MOF, these partially decomposed composite materials exhibit significantly stronger catalytic activity towards PMS, efficiently removing organic pollutants such as tetracycline (TC). After optimization, the sample treated at 400 °C, under visible light with PMS assistance, achieves an impressive degradation rate, almost completely degrading a 50 mL TC solution (10 mg/L) after 80 min. This achievement surpasses the degradation rate observed with the original Cu-MOF by 2.1 times. In the composite system of CuxO/NC/Cu-MOF+PMS+Vis, the significant enhancement of activity is credited to the effective spatial separation of photogenerated electrons and holes, as well as the utilization of 1O2 as the primary active oxygen species. This work provides a simple preparation strategy for the development of Cu-based PMS activators with excellent photocatalytic performance.

Facile synthesis of a novel CeCO3OH@(H/C–CdS) catalyst with synergistic effect of heterophase junction and heterojunction for enhanced visible-light photocatalytic degradation efficiency at room temperature

A new CeCO3OH@(hexagonal/cubic phases–CdS) (CeCO3OH@(H/C–CdS)) composite catalyst was facilely synthesized by a simple microinjection titration–stirring method, in which CdS nanoparticles were dispersed on the surface of CeCO3OH nanolines. The optimal conditions for the preparation of composite catalysts with high photocatalytic performance were determined by single-factor experiments and response surface experiments. Under these conditions, the degradation rate of 30 mL 2.000 g/L rhodamine B (Rh B) by CeCO3OH@(H/C-CdS) in a photocatalytic reaction for 1 h at 25 °C was up to 86.81 % and its degradation rate in a photocatalytic reaction for 150 min was up to 99.62 %. The degradation rate could be maintained above 80 % even after six times recycling. Especially, the photocatalytic degradation efficiency of 2.000 g/L Rh B on the composite catalyst under sunlight and at room temperature for 30 min reached 97.66 %. Meanwhile, the large size of CeCO3OH considerably alleviated the agglomeration of CdS, providing more adsorption and active sites for visible light-mediated degradation of Rh B. Importantly, the Z-scheme charge transfer realized by CdS and CeCO3OH enhanced the efficient separation of photogenerated electrons and holes, and successfully inhibited the recombination of photogenerated electrons with holes. At the same time, owing to the low energy band difference between the two phases of CdS, charge was transferred between the hexagonal and cubic phases, leaving more effective photogenerated charge to participate in the degradation of Rh B. The synergism of the heterophase junction and heterojunction and the presence of oxygen and sulfur vacancies considerably enhanced the degradation performance of the catalyst. Thus, this study provides a new strategy for the modification and enhanced visible-light catalysis performance of CdS-based catalysts.

Construction of S‐Scheme Alkalized C3N4/ZnO Piezo‐Photocatalyst with Improved Degradation Activity

AbstractThe construction of heterojunctions is often considered an effective strategy for achieving visible light driven photocatalytic degradation of organic pollutants. In this work, defective g‐C3N4 ultrathin nanosheets were synthesized via alkaline etching method. Subsequently, a S‐scheme heterojunction was constructed between the contact interface of ZnO nanorods and alkaline C3N4 (aC3N4) to promote the electron transfer, resulting in a novel piezo‐photocatalyst (aC3N4/ZnO). The piezo‐photocatalytic performance of aC3N4/ZnO samples with different ratios was studied by adjusting the addition amount aC3N4. In addition, optimum 7 %‐aC3N4/ZnO samples exhibited the highest piezo‐photocatalytic degradation activity under light and ultrasonic irradiation with MB as the target pollutant, exhibiting the 99.89 % degradation rate and 65.68 % mineralization rate within 50 minutes. The capture experiments showed that 1O2,⋅O2− and ⋅OH were active substances in promoting the performance of piezo‐photocatalysis. The mechanism studies indicated that the enhanced piezo‐photocatalytic activity can be attributed to the synergistic effect of the piezoelectric properties of ZnO and the S‐scheme heterojunction formed at the aC3N4/ZnO interfaces, which provides power for the separation and transport of electron and hole. This work highlights the importance of carefully construction S‐scheme heterojunction and defective structures to precisely understand the catalytic properties, benefiting catalytic design and development.

Piezoelectric Bilayer Nickel-Iron Layered Double Hydroxide Nanosheets with Tumor Microenvironment Responsiveness for Intensive Piezocatalytic Therapy.

Piezocatalytic therapy (PCT) based on 2D layered materials has emerged as a promising non-invasive tumor treatment modality, offering superior advantages. However, a systematic investigation of PCT, particularly the mechanisms underlying the reactive oxygen species (ROS) generation by 2D nanomaterials, is still in its infancy. Here, for the first time, biodegradable piezoelectric 2D bilayer nickel-iron layered double hydroxide (NiFe-LDH) nanosheets (thickness of ≈1.86nm) are reported for enhanced PCT and ferroptosis. Under ultrasound irradiation, the piezoelectric semiconducting NiFe-LDH exhibits a remarkable ability to generate superoxide anion radicals, due to the formation of a built-in electric field that facilitates the separation of electrons and holes. Notably, the significant excitonic effect in the ultrathin NiFe-LDH system enables long-lived excited triplet excitons (lifetime of ≈5.04µs) to effectively convert triplet O2 molecules into singlet oxygen. Moreover, NiFe-LDH exhibited tumor microenvironment (TME)-responsive peroxidase (POD)-like and glutathione (GSH)-depleting capabilities, further enhancing oxidative stress in tumor cells and inducing ferroptosis. To the best of knowledge, this is the first report on piezoelectric semiconducting sonosensitizers based on LDHs for PCT and ferroptosis, providing a comprehensive understanding of the piezocatalysis mechanism and valuable references for the application of LDHs and other 2D materials in cancer therapy.

Theoretical Analysis of Superior Photodegradation of Methylene Blue by Cerium Oxide/Reduced Graphene Oxide vs. Graphene.

Density functional theory and a semi-empirical quantum chemical approach were used to evaluate the photocatalytic efficiency of ceria (CeO2) combined with reduced graphene oxide (rGO) and graphene (GP) for degrading methylene blue (MB). Two main aspects were examined: the adsorption ability of rGO and GP for MB, and the separation of photogenerated electrons and holes in CeO2/rGO and CeO2/GP. Our results, based on calculations of the adsorption energy, population analysis, bond strength index, and reduced density gradient, show favorable energetics for MB adsorption on both rGO and GP surfaces. The process is driven by weak, non-covalent interactions, with rGO showing better MB adsorption. A detailed analysis involving parameters like fractional occupation density, the centroid distance between molecular orbitals, and the Lewis acid index of the catalysts highlights the effective charge separation in CeO2/rGO compared to CeO2/GP. These findings are crucial for understanding photocatalytic degradation mechanisms of organic dyes and developing efficient photocatalysts.

Advancing Electrically Conductive Metal-Organic Frameworks for Photocatalytic Energy Conversion.

ConspectusPhotocatalytic energy conversion is a pivotal process for harnessing solar energy to produce chemicals and presents a sustainable alternative to fossil fuels. Key strategies to enhance photocatalytic efficiency include facilitating mass transport and reactant adsorption, improving light absorption, and promoting electron and hole separation to suppress electron-hole recombination. This Account delves into the potential advantages of electrically conductive metal-organic frameworks (EC-MOFs) in photocatalytic energy conversion and examines how manipulating electronic structures and controlling morphology and defects affect their unique properties, potentially impacting photocatalytic efficiency and selectivity. Moreover, with a proof-of-concept study of photocatalytic hydrogen peroxide production by manipulating the EC-MOF's electronic structure, we highlight the potential of the strategies outlined in this Account.EC-MOFs not only possess porosity and surface areas like conventional MOFs, but exhibit electronic conductivity through d-p conjugation between ligands and metal nodes, enabling effective charge transport. Their narrow band gaps also allow for visible light absorption, making them promising candidates for efficient photocatalysts. In EC-MOFs, the modular design of metal nodes and ligands allows fine-tuning of both the electronic structure and physical properties, including controlling the particle morphology, which is essential for optimizing band positions and improving charge transport to achieve efficient and selective photocatalytic energy conversion.Despite their potential as photocatalysts, modulating the electronic structure or controlling the morphology of EC-MOFs is nontrivial, as their fast growth kinetics make them prone to defect formation, impacting mass and charge transport. To fully leverage the photocatalytic potential of EC-MOFs, we discuss our group's efforts to manipulate their electronic structures and develop effective synthetic strategies for morphology control and defect healing. For tuning electronic structures, diversifying the combinations of metals and linkers available for EC-MOF synthesis has been explored. Next, we suggest that synthesizing ligand-based solid solutions will enable continuous tuning of the band positions, demonstrating the potential to distinguish between photocatalytic reactions with similar redox potentials. Lastly, we present incorporating a donor-acceptor system in an EC-MOF to spatially separate photogenerated carriers, which could suppress electron-hole recombination. As a synthetic strategy for morphology control, we demonstrated that electrosynthesis can modify particle morphology, enhancing electrochemical surface area, which will be beneficial for reactant adsorption. Finally, we suggest a defect healing strategy that will enhance charge transport by reducing charge traps on defects, potentially improving the photocatalytic efficiency.Our vision in this Account is to introduce EC-MOFs as an efficient platform for photocatalytic energy conversion. Although EC-MOFs are a new class of semiconductor materials and have not been extensively studied for photocatalytic energy conversion, their inherent light absorption and electron transport properties indicate significant photocatalytic potential. We envision that employing modular molecular design to control electronic structures and applying effective synthetic strategies to customize morphology and defect repair can promote charge separation, electron transfer to potential reactants, and mass transport to realize high selectivity and efficiency in EC-MOF-based photocatalysts. This effort not only lays the foundation for the rational design and synthesis of EC-MOFs, but has the potential to advance their use in photocatalytic energy conversion.

Signal-on sensor using MOF-MoS2 with high-performance photoelectrochemical activity for specific detection of Hg2+

Mercury is a common, bioaccumulative, and highly toxic pollutant, and its harmful effects on the human body and environment should not be underestimated. In this study, an enzyme-free photoelectrochemical (PEC) analysis method based on signal-on detection was developed using a novel photoelectrochemically active material, metal–organic framework (MOF)-MoS2, for the specific detection of Hg2+. Driven by visible light, MOF-MoS2 can be used as a PEC sensitizer and Hg2+ recognition probe. With the addition of Hg2+, the active sulfur sites on the MOF-MoS2/F-doped tin oxide surface specifically combined to yield HgS, which was further used for signal amplification and specifically turned on the photocurrent response of the electrode. In addition, the p–n junction formed between the MOF-MoS2/HgS complexes triggered the development of MOF-MoS2 composites in the direction of electron–hole separation, leading to an increase in optoelectronic signals. Importantly, the PEC sensor detected Hg2+ over a wide linear range from 0.01 to 1000 nM, with a limit of detection of 0.25 pM. The fabricated sensor exhibited good stability, excellent reproducibility, and specificity. The PEC platform may provide new insights into the non-intrusive detection of Hg2+ in human and water samples.

Surface Oxygen Vacancies and Corona Polarization of Bi4Ti3O12 Nanosheets for Synergistically Enhanced Sonopiezoelectric Therapy.

Sonopiezoelectric therapy, an ultrasound-activated piezoelectric nanomaterial for tumor treatment, has emerged as a novel alternative modality. However, the limited piezoelectric catalytic efficiency is a serious bottleneck for its practical application. Excellent piezoelectric catalysts with high piezoelectric coefficients, good deformability, large mechanical impact surface area, and abundant catalytically active sites still need to be developed urgently. In this study, the classical ferroelectric material, bismuth titanate (Bi4Ti3O12, BTO), is selected as a sonopiezoelectric sensitizer for tumor therapy. BTO generates electron-hole pairs under ultrasonic irradiation, which can react with the substrates in a sonocatalytic-driven redox reaction. Aiming to further improve the catalytic activity of BTO, modification of surface oxygen vacancies and treatment of corona polarization are envisioned in this study. Notably, modification of the surface oxygen vacancies reduces its bandgap and inhibits electron-hole recombination. Additionally, the corona polarization treatment immobilized the built-in electric field on BTO, further promoting the separation of electrons and holes. Consequently, these modifications greatly improve the sonocatalytic efficiency for in situ generation of cytotoxic ROS and CO, effectively eradicating the tumor.

Constructing cascade electric fields and sulfur vacancies in Ni3S4/NiS2/v-Zn3In2S6 photocatalyst for efficient degradation of contaminants and H2 production

The increasing environmental pollution and looming energy crisis necessitate the development of advanced photocatalysts that demonstrate efficient separation and transfer of the photo-generated holes and electrons, as well as multiple functions to address the above issues. Herein, a bifunctional Ni3S4/NiS2/v-Zn3In2S6 photocatalyst has been constructed to degrade environmental hormones and antibiotics with simultaneous H2 production. Sulfur vacancies have been engineered in the Zn3In2S6 from a kinetic point of view to accelerate the separation of photogenerated charge carriers and act as active sites. Ni3S4 and NiS2 are introduced to construct cascade electric fields with Zn3In2S6 via ohmic junctions for spatially separated charge carriers and reduced hydrogen evolution potential. As a result, the composite exhibits enhanced photocatalytic H2 production and efficient degradation of bisphenol A, norfloxacin, and tetracycline, respectively. Specifically, the degradation pathways of BPA have been investigated based on Fukui calculations and liquid chromatography-mass spectrometry techniques. This work may shed new light on the design and construction of dual-function photocatalysts for wastewater treatment and H2 production.

Constructing ZnIn2S4@WO3·H2O Z-type heterojunction to boost photocatalytic efficiency under visible-light irradiation

In this paper, hexagonal ZnIn2S4 nanoflowers were grown in situ on tetragonal WO3·H2O nanosheets, yielding a compact ZnIn2S4@WO3·H2O (ZIS@WO) core-shell heterojunction. The formation of the ZIS@WO heterojunction was optimized by meticulously adjusting the quantity of WO3·H2O nanosheets incorporated. The crystal structure and microstructure of ZIS@WO were comprehensively examined using XRD, TEM and EDS analyses. The photocatalytic properties of ZIS@WO heterojunctions were evaluated through the degradation of organic pollutants under visible light irradiation. The results demonstrated a marked enhancement in photocatalytic efficiency for the ZIS@WO heterojunction. Further investigation into the separation and transport of photogenerated carriers were performed using PL spectroscopy and photoelectrochemical measurement. Compared to the individual components of ZnIn2S4 nanoflowers and WO3·H2O nanosheets, the ZIS@WO heterojunction creates an internal electric field at the interface, along with a compact core-shell configuration. This internal electric field, in conjunction with the band structure of the heterojunction, effectively accelerates the separation of photogenerated electrons and holes. Additionally, a comprehensive analysis of the photocatalytic degradation mechanisms were presented, elucidating the intricate processes.

Nanofibrous La0.95K0.05MnO3 perovskite with improved photoelectrical properties for photocatalytic degradation of antibiotics

Potassium doped lanthanum manganese perovskite oxides, La1−xKxMnO3, with nanofibrous structure, are prepared and used for Photo-Fenton degradation of antibiotics, including ciprofloxacin (CIP), tetracycline (TC), and sulfathiazole (ST). Effects of K doping on the textural structure, optical property, band gap and surface chemistry of LaMnO3 are investigated, showing that La0.95K0.05MnO3 (LKMO-5) has the optimal properties. The photoelectric measurements, including photoluminescence (PL), photocurrent response (PCR) and electrochemical impedance spectroscopy (EIS), also suggest that the LKMO-5 has the best electron–hole separation efficiency, the most amounts of irradiated electrons and the lowest impedance. Photocatalytic tests indicate that LKMO-5 not only shows the best activity for CIP degradation, but also exhibits good stability in the reaction, with negligible activity loss within four cycles. Mechanism investigations, explored by the radical trapping experiments and with the reference of band positions, indicate that superoxide radical ions (·O2−) and holes (h+) are the major reactive species of the reaction.

Femtosecond laser ablated trench array for improving performance of commercial solid oxide cell

The performance of electrode-supported solid oxide cells (SOCs) is limited adversely by gas diffusion impedance in thick and porous support. This work focuses on the improvement of gas transport properties of commercial Ni-YSZ anode-supported SOFC by femtosecond laser-based micromachining where micro-holes of identical depth but different hole separations pitches with minimal heated affected zones were imposed. The polarization resistance calculations and DRT analysis revealed that the presence of the micro-holes improves fuel transport in the anode active zone of commercial SOFC. The presence of the micro-holes resulted in up to 20.8 % and up to 17.2 % reduction in polarization resistance for dry H2 and wet H2 gas-fueled SOFC samples, respectively. Moreover, the decrease in intensity of peaks responsible for fuel diffusion with increasing micro-holed density was observed. Therefore, dense and sparse cells exhibited a performance augmentation of 25 % and 11 % in dry H2 and enhancement of 16 % and 15.6 % in wet H2, respectively. Fs-laser ablation appeared as a unique capability for the post-processing of SOFC elements via imposing different gas channel geometries.

Designing Zn-MOF/AgCl composites for the photocatalytic degradation of rhodamine B dye and tetracycline antibiotic

The agglomeration tendency of AgCl, as a photocatalyst, hampers its advancement and practical application. In this paper, a simple composite method is designed based on the precipitation characteristics of AgCl. Ag+ ions introduced from outside combines with Cl− anions in complex [Zn(L)Cl]n (M1) [L = 2-(1-(carboxymethyl)-1H-benzo [d] imidazol-3-ium-3-yl)acetate)] to directly form Zn-MOF/AgCl composites (ZA-x, x = 0.5, 1 and 2), which may effectively prevent agglomeration of AgCl. The morphology and structure analysis displays a remarkable dispersity of AgCl. Further characterization and analysis of PL, UV–Vis, EIS, and TPC reveal that the composites have potential as excellent photocatalysts. The subsequent visible light catalytic degradation of Rhodamine B (RhB) and tetracycline hydrochloride (TC) has shown that the optimal composite ZA-0.5 with M1 to AgCl ratio of 1:0.5 exhibits the highest degradation efficiency in the 20 mg/L solution of RhB or TC, achieving 99.1 % for RhB within 20 min and 81.9 % for TC within 50 min. The free radical trapping test shows that ⋅O2− is the main catalytic species in the degradation process. In addition, the possible degradation mechanism was analyzed by VB-XPS and LC-MS. In a word, the in-situ combination of Cl− in M1 with Ag+ improves the dispersity of AgCl, enhances the interaction between M1 and AgCl, and leads to the effetive separation of electrons and holes, therefore improving the photocatalytic performance.

Wood Ion Pumps Enabled by Light-Responsive MoS2-Decorated Nanocellulosic Channels.

Light-driven active ion transport discovered in nanomaterials (e.g., graphene, metal-organic framework, and MXene) implicates crucial applications in membrane-based technology and energy conversion systems. However, it remains a challenge to achieve bulk assembly. Herein, we employ the scalable wood as a framework for in situ growth of MoS2 nanosheets to facilitate light-responsive ion transport. Owing to the aligned and negatively charged wood nanochannels, the MoS2-decorated wood exhibits an excellent nanofluidic conductivity of 8.3 × 10-5 S cm-1 in 1 × 10-6 M KCl. Asymmetric light illumination creates the separation of electrons and holes in MoS2 nanosheets, enabling ions to move uphill against a wide range of concentration gradients. As a result, the MoS2-decorated wood can pump ions uphill against a 20-fold concentration gradient at a light intensity of 300 mW cm-2. When the illumination is applied to the opposite side, the osmotic current along the 20-fold concentration gradient can be enhanced to 75.1 nA, and the corresponding osmotic energy conversion power density increases to more than 12.6 times that of the nonilluminated state. Based on the light-responsive behaviors, we are extending the use of MoS2-decorated wood as the ionic elements for nanofluidic circuits, such as ion switches, ion diodes, and ion transistors. This work provides a facile and scalable strategy for fabricating light-controlled nanofluidic devices from biomass materials.

The electronic stopping power of self-irradiated molybdenum in different charge states

Molybdenum is not only an excellent photovoltaic material but also a crucial component in semiconductors. However, its high bandgap restricts its application in optoelectronic devices. This limitation arises primarily because the energy barrier between photogenerated electron-hole pairs cannot be directly overcome by sunlight. Self-irradiation can overcome these barriers, allowing efficient separation of photogenerated electrons and holes, making molybdenum an excellent light-absorbing material. By altering the charge state of molybdenum-based materials, their light absorption can be adjusted. This project aims to systematically study the optical properties and electronic stopping power of molybdenum-based materials in different charge states through theoretical calculations and experiments.

Integrating Polyoxometalates and Silver Clusters into Atomically Precise Molecular Heterojunction.

The Ag cluster-POM assemblies have been shown to possess interesting and potentially useful properties. However, there is no precedent example of atomically precise Ag cluster-POM assemblies showing heterojunction effects in photocatalysis. Herein, the synthesis and total structure determination of the periodically distributed molecular heterojunction [Ag12(SCy)6(CH3CN)12(PW12O40)]n (Ag12-PW12) are reported. The assembly of Ag/W clusters into 3D network can endow the resulting binary structure with an aesthetic topology and unique physicochemical properties. More remarkably, the incorporation of Ag12 cluster with PW12 can efficiently facilitate the separation of photogenerated electrons and holes, thus significantly promoting the catalytic efficiency in selective oxidation of sulfides. The Ag12-PW12 heterojunction can be recovered and reused five times with no drastic change in the catalytic performance. This research is expected to assist in the rational design of cluster-based heterojunction catalysts. The increase of catalytic activity of the Ag12-PW12 assembly in comparison with the unassembled Ag12 and PW12 clusters is attributed to the synergistic effect of Ag12 and PW12 clusters, offering the splendid opportunity for deciphering structure-reactivity relationship of heterostructure-coupled photosystem.

Nitrogen vacancy-modified g-C3N4 nanosheets controlled by deep eutectic solvents for highly efficient photocatalytic atrazine degradation: Non-radical dominated holes oxidation

Metal-free photocatalysts like graphitic carbon nitride (g-C3N4) can have their electronic structures altered by vacancy defect engineering, greatly increasing their catalytic activity. Here, we have synthesized nitrogen vacancy mediated carbon nitride (DCNA) modified by deep eutectic solvents for the first time, DCNA showed 4.93-fold improvement compared to pristine g-C3N4 towards photocatalytic degradation of atrazine (ATZ). Besides, we have revealed the role of photogenic holes as the main active species for the photocatalytic degradation of ATZ. This improvement is attributed to the increased nitrogen vacancy, which increases the adsorption of N–H on the ATZ side chain, accelerates the process of photoelectron and hole separation, and allows more holes to participate in ATZ degradation. Moreover, the wheat growth toxicity test significantly reduced the degradation byproducts’ toxicity. This study provides an effective method for preparing environmentally friendly metal-free photocatalysts with high catalytic performance.

Nanoengineering construction of g-C3N4/Bi2WO6 S-scheme heterojunctions for cooperative enhanced photocatalytic CO2 reduction and pollutant degradation

S-scheme heterojunction photocatalysts featuring efficient charge transport paths provide a promising strategy for cooperative achieving photocatalytic CO2 reduction reaction (CO2RR) and Rhodamine B (RhB) degradation. In this work, S-scheme heterojunctions composed of g-C3N4 nanosheets coated on Bi2WO6 nanosheets were prepared by a one-step hydrothermal method, resulting in broad-spectrum light absorption, high electron–hole separation efficiency, and excellent photocatalytic CO2 reduction and RhB oxidization performance. Mechanistic analysis revealed the formation of a directional charge transport path at the interface of the heterojunction, which maintained a high oxidation and reduction potential and improved the efficiency of photoexcited carrier separation. In particular, the synergistic reaction system showed excellent photoredox activity compared with the two separate half-reactions. The optimal catalyst 15CN/BWO displayed the highest CO2 conversion efficiency, with CO and CH4 generation rates of 4.3 and 2.7 μmol g−1h−1, respectively, and the degradation efficiency of the composite heterojunction was significantly higher than that of its constituent materials. This work provides a new possibility for designing a novel dual-function photocatalytic reaction system.

Dual–Acceptor Engineering in Pyrene‐Based Covalent Organic Frameworks for Boosting Photocatalytic Hydrogen Evolution

AbstractThe integration of electron donor (D) and acceptor (A) units into covalent organic frameworks (COFs) has received increasing interest due to its potential for efficient photocatalytic hydrogen (H2) evolution from water. Nevertheless, the advancement of D–A COFs is still constrained by the limited investigations on acceptor engineering, which enables the highly effective charge transfer pathways in COFs to deliver photoexcited electrons in a preferential orientation to enhance photocatalytic performance. Herein, two systems with D–A and D–A–A configurations based on the acceptor molecular engineering strategy are proposed to construct three distinct COFs. Specifically, TAPPy‐DBTDP‐COF merging one pyrene‐based donor and two benzothiadiazole acceptors realized an average H2 evolution rate of 12.7 mmol h−1 g−1 under visible light, among the highest ever reported for typical D–A‐type COF systems. The combination of experimental and theoretical analysis signifies the crucial role of the dual‐acceptor arrangement in promoting exciton dissociation and carrier migration. These findings underscore the significant potential of D–A–A structural design, which is conducive to the efficient separation of photoexcited electrons and holes resulting in superior photocatalytic activities.