Single Photocatalyst Research Articles

Highly Active Photoreduction of Atmospheric‐Concentration CO2 into CH3COOH over Palladium Particles on Nb2O5 Nanosheets

AbstractThe endeavor to drive CO2 photoreduction towards the synthesis of C2 products is largely thwarted by the colossal energy hurdle inherent in C−C coupling. Herein, we load active metal particles on metal oxide nanosheets to build the dual metal pair sites for steering C−C coupling to form C2 products. Taking Pd particles anchored on the Nb2O5 nanosheets as an example, the high‐angle annular dark‐field image and X‐ray photoelectron spectroscopy demonstrate the presence of Pd−Nb metal pair sites on the Pd‐Nb2O5 nanosheets. Density functional theory calculations reveal these sites exhibit a low reaction energy barrier of only 1.02 eV for C−C coupling, implying that the introduction of Pd particles effectively tailors the reaction step to form C2 products. Therefore, the Pd‐Nb2O5 nanosheets achieve a CH3COOH evolution rate of 13.5 μmol g−1 h−1 in photoreduction of atmospheric‐concentration CO2, outshining all other single photocatalysts reported to date under analogous conditions.

Hierarchical Ag3VO4 Nanorods as an Excellent Visible Light Photocatalyst for CO2 Conversion to Solar Fuels

The potential of photocatalytic CO2 conversion is significant for the production of fuels and chemicals, while simultaneously mitigating CO2 emissions and addressing environmental concerns. Despite the current drawbacks of single metal-based photocatalysts, such as lower performance, uncontrollable selectivity, and instability, this study focuses on the synthesis of Ag3VO4 nanorods using the sol–gel method. The goal is to create a highly effective catalyst for visible light-responsive CO2 conversion. The successful synthesis of Ag3VO4 nanorods with a nanorod structure, functional under visible light, resulted in the highest yields of CH4 and dimethyl ether (DME) at 271 and 69 µmole/g-cat, respectively. The optimized Ag3VO4 nanorods demonstrated performance improvements, with CH4 and DME production 6.4 times and 4.5 times higher than when using V2O5 samples. This suggests that Ag3VO4 nanorods facilitate electron transfer to CO2, offer short pathways for electron transfer, and create empty spaces within the nanorods as electron reservoirs, enhancing the photoactivity. The prolonged stability of Ag3VO4 in the CO2 conversion system confirms that the nanorod structure provides controllable selectivity and stability. Therefore, the fabrication of nanorod structures holds promise in advancing high-performance photocatalysts in the field of photocatalytic CO2 conversion to solar fuels.

Carbosulfonylation of Alkynes: A Direct Conversion of sp-C to sp3-C through Visible Light-Mediated 3-Component Reaction.

A 3-component metal-free carbosulfonylation of alkynes is reported using readily available alkyl carboxylic acids and arylsulfinates under visible light irradiation. This photochemical approach gives direct conversion of sp-C to sp3-C yielding highly functionalized alkyl sulfones. It employs feedstock chemicals as starting materials and shows a broad substrate scope and moderate diastereoselectivity. The method's utility is highlighted in the synthesis of sedum alkaloids. A single photocatalyst is proposed to be active in two distinct photocatalytic cycles operating in tandem.

Highly Active Photoreduction of Atmospheric-Concentration CO2 into CH3COOH over Palladium Particles on Nb2O5 Nanosheets.

The endeavor to drive CO2 photoreduction towards the synthesis of C2 products is largely thwarted by the colossal energy hurdle inherent in C-C coupling. Herein, we load active metal particles on metal oxide nanosheets to build the dual metal pair sites for steering C-C coupling to form C2 products. Taking Pd particles anchored on the Nb2O5 nanosheets as an example, the high-angle annular dark-field image and X-ray photoelectron spectroscopy demonstrate the presence of Pd-Nb metal pair sites on the Pd-Nb2O5 nanosheets. Density functional theory calculations reveal these sites exhibit a low reaction energy barrier of only 1.02 eV for C-C coupling, implying that the introduction of Pd particles effectively tailors the reaction step to form C2 products. Therefore, the Pd-Nb2O5 nanosheets achieve a CH3COOH evolution rate of 13.5 μmol g-1 h-1 in photoreduction of atmospheric-concentration CO2, outshining all other single photocatalysts reported to date under analogous conditions.

Preparation and photocatalytic mechanism of magnetic Ag2S/CoFe1.95Dy0.05O4 Z‐scheme heterojunction

AbstractThe synthesis of high‐efficiency magnetic composite photocatalyst by doping magnetic cobalt ferrite and compounding single semiconductor photocatalyst is a promising strategy to improve the oxidation ability of photocatalytic systems. In this paper, CoFe1.95Dy0.05O4 (CFDO) was prepared by doping Dy element into magnetic CoFe2O4, and Ag2S (AS)/CFDO with high‐efficiency magnetic photocatalyst was synthesized by compounding AS with CFDO as the substrate. The photocatalytic samples were characterized by different advanced characterization methods, and their photocatalytic degradation of methylene blue (MB) was studied. The results show that AS/CFDO exhibits higher visible light response, excellent photogenerated charge separation ability and migration efficiency, and excellent catalytic performance in the catalytic degradation system. The photocatalytic activity of AS/CFDO was the highest, and its photocatalytic degradation kinetic constant K was 2.48 and 1.54 times that of AS and CFDO, respectively. In addition, the catalyst contained in the catalytically contaminated solution can be effectively separated by an external magnetic field to achieve multiple cycles of degradation and recycling. The cyclic degradation experiments showed that AS/CFDO exhibited high degradation stability during the photodegradation process. After the fifth reuse, the degradation efficiency was still more than 88.0%. Finally, the possible photocatalytic mechanism of the samples was discussed. Therefore, this work provides an effective solution for the construction of photocatalysts with high efficiency, magnetic recovery, and cyclic degradation stability and avoids the secondary pollution of catalysts to organic wastewater. It is of great significance to create an environmentally friendly catalytic method for efficient cyclic degradation of organic wastewater.

Improvement of photocatalytic hydrogen production performance of ZnO with Bi2X3 (X = Te, Se)

ABSTRACT Harnessing photocatalysts to facilitate the visible-light-driven breakdown of water molecules is esteemed as a highly auspicious and ecologically sustainable approach for hydrogen production. This study aimed to improve the hydrogen production performance of single ZnO photocatalysts by preparing efficient Bi2Te3/ZnO and Bi2Se3/ZnO composite photocatalysts by microwave method. During the synthesis process, both Bi2Te3 and Bi2Se3 were fully fused and reacted with ZnO to form heterojunctions using magnetic stirring and microwave heating. The experimental results indicate a significant enhancement in the hydrogen production activity of the BT-Z and BS-Z composite photocatalysts. When the Bi2Te3 content is 5%, with a microwave temperature maintained at 135 °C and a microwave time of 90 min, the hydrogen production rate reaches 664.286 μmol∙h−1∙g−1 within 4 hr. On the other hand, when the Bi2Se3 content is 5%, with a microwave temperature maintained at 135 °C and a microwave time of 90 min, the hydrogen production rate reaches 515.306 μmol∙h−1∙g−1 within 4 hr.

Recent research progress of MOFs-based heterostructures for photocatalytic hydrogen evolution

The growing serious energy crisis and environmental pollution expedite the development of green hydrogen energy. Photocatalytic water splitting technology, converting solar energy into chemical energy directly, provides a clean and economical way for hydrogen evolution. For the past few years, metal–organic frameworks (MOFs) semiconductor materials have become a research hotspot in the field of photocatalytic hydrogen evolution (PHE) due to their multiple advantages, including adjustable structure, high porosity, large specific surface area, abundant active sites, and so forth. Besides this, the construction of heterogeneous structures based on MOFs materials can further improve PHE performance through the effective internal electric field directional transfer of photogenerated electrons and the superior utilization rate of sunlight in comparison to the single MOFs photocatalyst. Herein, in this minireview, we summed up the varieties of synthesis methods of diverse types of MOFs heterojunction complex materials, discussed the H2 evolution efficiency based on this heterostructure photocatalyst in detail, and lastly proposed the advantages, limitations, and outlook of MOFs composites in the PHE field. We sincerely hope this review can provide a reference for future research based on MOFs materials for alleviating the current energy crisis.

Attuned band structure in triple S-scheme heterojunctions for naproxen degradation under visible light

The limited charge carrier separation and transportation in single semiconductor photocatalysts has lobbied research and development in rational design and fabrication of heterojunction photocatalysts which has become a hot topic in the last decade. In-depth investigation of a four-component semiconductors interfacial charge transfer analysis considering the contribution of all components was done for the first time to deduce triple S-scheme heterojunction. This work investigated four-component semiconductors (Cu3(PO4)2, BaWO4, C-MgO and LDH) heterojunction photocatalyst formation by the solvothermal method for visible light degradation of NPX. The degradation rate of CBLM-B (0.0429 min−1) with high BaWO4 content was two times the degradation rate of CBLM-A (0.0203 min−1) with high LDH/C-MgO content. XPS, electrochemistry, and band structure analysis were used to propose a triple S-scheme heterojunction with high electron mobility and charge separation that enhanced the formation of OH• >•O2− > h+ species as supported by radical trapping experiments due to presence of two oxidative and two reductive sites for stable generation of ROSs. Internal electric field (IEF) and band bending modulated an S-S interfacial strategy at the three junctions. Cu leaching affected the catalyst stability, and NPX degradation pathways were investigated with QTOF-HPLC-MS. This work demonstrated band structure adjustment for design of highly efficient triple S-Scheme heterojunctions application in environmental pollution remediation as a new development to advance scientific knowledge on four-component heterojunctions which may also be described using the Z-scheme charge transfer model.

Hot Electrons Induced by Localized Surface Plasmon Resonance in Ag/g-C3N4 Schottky Junction for Photothermal Catalytic CO2 Reduction.

Converting carbon dioxide (CO2) into high-value-added chemicals using solar energy is a promising approach to reducing carbon dioxide emissions; however, single photocatalysts suffer from quick the recombination of photogenerated electron-hole pairs and poor photoredox ability. Herein, silver (Ag) nanoparticles featuring with localized surface plasmon resonance (LSPR) are combined with g-C3N4 to form a Schottky junction for photothermal catalytic CO2 reduction. The Ag/g-C3N4 exhibits higher photocatalytic CO2 reduction activity under UV-vis light; the CH4 and CO evolution rates are 10.44 and 88.79 µmol·h-1·g-1, respectively. Enhanced photocatalytic CO2 reduction performances are attributed to efficient hot electron transfer in the Ag/g-C3N4 Schottky junction. LSPR-induced hot electrons from Ag nanoparticles improve the local reaction temperature and promote the separation and transfer of photogenerated electron-hole pairs. The charge carrier transfer route was investigated by in situ irradiated X-ray photoelectron spectroscopy (XPS). The three-dimensional finite-difference time-domain (3D-FDTD) method verified the strong electromagnetic field at the interface between Ag and g-C3N4. The photothermal catalytic CO2 reduction pathway of Ag/g-C3N4 was investigated using in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS). This study examines hot electron transfer in the Ag/g-C3N4 Schottky junction and provides a feasible way to design a plasmonic metal/polymer semiconductor Schottky junction for photothermal catalytic CO2 reduction.

Chemically bonded CdBiO2Br/BiOI heterojunction with strong interfacial electric field for enhanced photocatalysis

Semiconductor-based photocatalysis shows a large potential for contaminant purification, however, a single semiconductor photocatalyst suffers from low utilization efficiency of photogenerated carriers, leading to inferior photocatalytic activity. Herein, CdBiO2Br@BiOI (CBOB@BiOI) heterojunction with a close interface interaction is prepared by a facile precipitation method at the ambient atmosphere. X-ray photoelectron spectroscopy and Density Functional Theory calculations on work function consistently disclose that the formation of CdBiI bonds at the interface induces the electron migration from BiOI to CdBiO2Br, which allows CBOB@BiOI heterojunction to have a strong interfacial electric field (IEF) for efficiently separating photocharges. In-situ Kelvin-probe Force Microscopy measurement demonstrates that CBOB@BiOI heterojunction shows a larger surface potential than CdBiO2Br and BiOI in dark and a potential decrease under illumination, which can be ascribed to the photoinduced electron migration within heterojunction driven by the IEF. Thus, the CBOB@BiOI heterojunction shows a much more efficient photocatalytic activity for the breakdown of tetracycline hydrochloride (TC), which is 2.44 and 3.99 times higher than CdBiO2Br and BiOI, respectively. Electron Paramagnetic Resonance test also confirms that the CBOB@BiOI heterojunction produces much more superoxide radicals and holes as reactive species than CdBiO2Br and BiOI. Furthermore, the latent degradation pathways of TC are investigated by Liquid Chromatograph Mass Spectrometer. This work may provide new ideas for constructing intimately bonded heterojunction photocatalysts with a strong IEF for efficient photocatalytic activity.

The Role of Point Defects in Heterojunction Photocatalysts: Perspectives and Outlooks

AbstractThe development of efficient photocatalysts is a mainstay for the advancement of photocatalytic technology. Heterojunction photocatalysts can overcome the inherent limitations of single photocatalysts, integrating the advantages of each component, and achieving efficient separation of photogenerated charges, making them a research focus in the field of photocatalysis. The role of point defects in photocatalytic reactions is diverse and can significantly influence the performance of photocatalysts. This review comprehensively summarizes the latest advancements in point defect engineering for the modulation of heterojunction photocatalysts. First, the types of point defects and their impact on photocatalytic processes are introduced. Subsequently, the common types of heterojunction photocatalysts are presented. Then, in accordance with recent research progress, the regulatory mechanisms of point defects within heterojunction photocatalysts are outlined, with a particular focus on their functions on surface/interfacial properties and photogenerated charge transfer processes. Finally, the challenges faced by point defect engineering in optimizing heterojunction photocatalysts and promising solutions are proposed. This review provides an in‐depth understanding of the role of point defect engineering in heterojunction photocatalysts, with the expectation of offering insights into the development of highly active photocatalytic materials.

Metal single atom photocatalysts for sunlight-driven hydrogen production: Recent and future development

Photocatalytic hydrogen evolution has been considered the most compelling approach for green hydrogen technology. Heretofore, restricted light adsorption, fast charge recombination, and limited surface-active sites have been considered as bottle-neck issues, causing poor catalytic performance. In this context, metal single atom-incorporated photocatalysts have attracted tremendous attention for their ability to overcome these obstacles while maximizing atomic metal utilization efficiency. The presented perspective aims at highlighting the cutting-edge development of metal single-atom photocatalysts. Indeed, the formation manner and features of metal single atom- anchored photocatalysts are presented. Also, various preparation methods employed to deploy metal atoms onto parent materials are unveiled. Furthermore, recent outstanding metal single atom- anchored semiconductors, which are precious, transition, dual metal single atom- decorated are discussed in detail. In addition, it is also expected to pave the way for the next generation of photocatalysts for sunlight-driven hydrogen generation and contribute to fill the missing puzzles in the picture of green hydrogen production.

Oxygen Vacancies Trigger Rapid Charge Transport Channels at the Engineered Interface of S-Scheme Heterojunction for Boosting Photocatalytic Performance.

Although oxygen vacancies (Ovs) have been intensively studied in single semiconductor photocatalysts, exploration of intrinsic mechanisms and in-depth understanding of Ovs in S-scheme heterojunction photocatalysts are still limited. Herein, a novel S-scheme photocatalyst made from WO3-Ov/In2S3 with Ovs at the heterointerface is rationally designed. The microscopic environment and local electronic structure of the S-scheme heterointerface are well optimized by Ovs. Femtosecond transient absorption spectroscopy (fs-TAS) reveals that Ovs trigger additional charge movement routes and therefore increase charge separation efficiency. In addition, Ovs have a synergistic effect on the thermodynamic and kinetic parameters of S-scheme photocatalysts. As a result, the optimal photocatalytic performance is significantly improved, surpassing that of single component WO3-Ov and In2S3 (by 35.5 and 3.9 times, respectively), as well as WO3/In2S3 heterojunction. This work provides new insight into regulating the photogenerated carrier dynamics at the heterointerface and also helps design highly efficient S-scheme photocatalysts.

Oxygen Vacancies Trigger Rapid Charge Transport Channels at the Engineered Interface of S‐Scheme Heterojunction for Boosting Photocatalytic Performance

AbstractAlthough oxygen vacancies (Ovs) have been intensively studied in single semiconductor photocatalysts, exploration of intrinsic mechanisms and in‐depth understanding of Ovs in S‐scheme heterojunction photocatalysts are still limited. Herein, a novel S‐scheme photocatalyst made from WO3‐Ov/In2S3 with Ovs at the heterointerface is rationally designed. The microscopic environment and local electronic structure of the S‐scheme heterointerface are well optimized by Ovs. Femtosecond transient absorption spectroscopy (fs‐TAS) reveals that Ovs trigger additional charge movement routes and therefore increase charge separation efficiency. In addition, Ovs have a synergistic effect on the thermodynamic and kinetic parameters of S‐scheme photocatalysts. As a result, the optimal photocatalytic performance is significantly improved, surpassing that of single component WO3‐Ov and In2S3 (by 35.5 and 3.9 times, respectively), as well as WO3/In2S3 heterojunction. This work provides new insight into regulating the photogenerated carrier dynamics at the heterointerface and also helps design highly efficient S‐scheme photocatalysts.

Fe-Doped g-C3N4/Bi2MoO6 Heterostructured Composition with Improved Visible Photocatalytic Activity for Rhodamine B Degradation.

The binary heterostructured semiconducting visible light photocatalyst of the iron-doped graphitic carbon nitride/bismuth molybdate (Fe-g-C3N4/Bi2MoO6) composite was prepared by coupling with Fe-doped g-C3N4 and Bi2MoO6 particles. In the present study, a comparison of structural characteristics, optical properties, and photocatalytic degradation efficiency and activity between Fe-doped g-C3N4 particles, Bi2MoO6 particles, and Fe-g-C3N4/Bi2MoO6 composite was investigated. The results of X-ray diffraction (XRD) examination indicate that the hydrothermal Bi2MoO6 particles have a single orthorhombic phase and Fourier transform infrared (FTIR) spectroscopy analysis confirms the formation of Fe-doped g-C3N4. The optical bandgaps of the Fe-doped g-C3N4 and Bi2MoO6 particles are 2.74 and 2.73 eV, respectively, as estimated from the Taut plots obtained from UV-Vis diffuse reflectance spectroscopy (DRS) spectra. This characteristic indicates that the two semiconductor materials are suitable for absorbing visible light. The transmission electron microscopy (TEM) micrograph reveals the formation of the heterojunction Fe-g-C3N4/Bi2MoO6 composite. The results of photocatalytic degradation revealed that the developed Fe-g-C3N4/Bi2MoO6 composite photocatalyst exhibited significantly better photodegradation performance than the other two single semiconductor photocatalysts. This property can be attributed to the heterostructured nanostructure, which could effectively prevent the recombination of photogenerated carriers (electron-hole pairs) and enhance photocatalytic activity. Furthermore, cycling test showed that the Fe-g-C3N4/Bi2MoO6 heterostructured photocatalyst exhibited good reproducibility and stability for organic dye photodegradation.

A novel noble-metal-free FeS2/Mn0.5Cd0.5S heterojunction for enhancing photocatalytic H2 production activity: Carrier separation, light absorption, active sites

BackgroundThe development of efficient and noble-metal-free photocatalysts is greatly essential for photocatalytic hydrogen production. However, the photocatalytic activity of a single photocatalyst is usually limited for various reasons. MethodsHerein, FeS2/Mn0.5Cd0.5S (FSMCS) heterojunctions were constructed by a simple solvent evaporation method. The morphological characterizations revealed a raspberry-like hollow microsphere structure for FeS2 and irregular granularity for Mn0.5Cd0.5S. Photoluminescence (PL) and electrochemical experiments indicated that the FSMCS composite effectively facilitated the separation of photogenerated electron-hole pairs. The UV–vis diffuse reflectance spectrum (DRS) showed that, in FSMCS composite, the visible light absorption range was effectively expanded to the full visible light. Significant findingsExcellent photocatalytic activity in FSMCS heterojunctions without loading noble metals because FeS2 could serve an active site for hydrogen production. The optimum FSMCS composite had excellent photocatalytic hydrogen production activity (6.1 mmol·g−1·h−1), which was 5.6 and 2.3 times higher than that of the pristine Mn0.5Cd0.5S (1.1 mmol·g−1·h−1) and Mn0.5Cd0.5S-1 %Pt (2.7 mmol·g−1·h−1). Meanwhile, in four round-robin tests, the activity of the 5FSMCS photocatalyst did not significantly decrease. This work proved that combining Mn0.5Cd0.5S and non-precious metal cocatalysts to construct heterojunctions is a promising strategy for photocatalytic hydrogen production.

Selective Photocatalytic CO2 Reduction Through Plasmonic Z‐Scheme Ag‐Bi2O3‐ZnO Heterostructures

AbstractCombination of plasmonic noble metal with semiconductors offers a promising and potential solar energy harvesting and conversion route. Herein, plasmonic Z‐scheme Ag‐Bi2O3‐ZnO (AgBZ) heterostructure is designed and synthesized via solution combustion and photo‐deposition method. Metallic Ag nanoparticles (NPs) were deposited over Bi2O3‐ZnO heterostructure; thus, they exhibit strong visible light absorption owing to surface plasmon resonance (SPR). The photocatalytic efficiency of the synthesized catalysts is investigated by the photocatalytic CO2 reduction to fuels under simulated solar light irradiation. The present system has shown an outstanding photocatalytic CO2 reduction and excellent selectivity of CO. The evolved rate of CO fuel, the amount of CO produced per unit time, over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was (96.74 μmol g−1/h) which was approximately 12 times larger than that of Bi2O3‐ZnO (0AgBZ) and 49‐fold than the quantity of evolved CO fuels over pure ZnO photocatalyst. The percentage of evolved CO to CH4 fuels over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was about 50 : 1compared to that of 2 : 3 over Bi2O3‐ZnO (0AgBZ). The great improvement and the high selectivity would be ascribed to the synergistic effect of metallic surface plasmon resonance and the Z‐scheme charges transfer system. This work would open a window to construct a single photocatalyst with different charge separation systems and excellent CO2 reduction selectivity. Finally, the mechanism for the enhanced photocatalytic performance by the synergistic effect was described and discussed.

High-Throughput Computational Screening of Novel Two-Dimensional Covalent Organic Frameworks for Efficient Photocatalytic Overall Water Splitting.

The pursuit of efficient photocatalysts toward photocatalytic water splitting has attracted wide attention. However, the low efficiency of photocatalytic reactions due to the rapid electron-hole recombination and the time-consuming searching process hinder the development of high-performance photocatalysts. Here, we proposed a data-driven screening procedure for covalent organic frameworks (COFs) as overall solar water-splitting photocatalysts. Based on a COF database through assembling different Cores and Linkers, three COFs are predicted to be efficient photocatalysts for overall solar water splitting after high-throughput computational screening. We found that the photogenerated electrons and holes are well separated on single COF photocatalysts without material engineering, and both hydrogen and oxygen evolution reactions can occur spontaneously on the three screened COFs under visible light radiation. This kind of novel COF screened by a data-driven screening procedure offers new perspectives for advancing efficient photocatalysts.

Three-dimension TiO2@NiFe-layered double hydroxide core-shell heterostructures for enhanced photocatalytic phenol hydroxylation

One-step selectively photocatalytic phenol hydroxylation to produce Dihydroxybenzenes (DHB) is an attractive and challenging strategy. However, the rapid recombination of photogenerated carriers existed in single component photocatalyst seriously hinders the photocatalytic efficiency. The heterojunction strategy can optimize the band structure of the photocatalyst, and effectively improve the carriers' separation and transfer during the photocatalytic process. Herein, we successfully designed and prepared a 3D TiO2@Ni3Fe1-LDH core-shell heterostructure photocatalyst by coupling TiO2 nanorods with Ni3Fe1-LDH nanosheets for the photocatalytic phenol hydroxylation to produce DHB. The results showed that the 3D TiO2@Ni3Fe1-LDH core-shell heterostructure had a suitable energy band structure for the photocatalytic phenol hydroxylation and the heterostructure accelerated the carriers’ separation and transfer. Meanwhile, the high porosity and abundant active sites were conducive to the adsorption of H2O2 and the photogenerated carriers transfer efficiency from the photocatalyst to H2O2. The 3D TiO2@Ni3Fe1-LDH core-shell heterostructure showed excellent photocatalytic performance of phenol hydroxylation, where the phenol conversion was 48.6%, and the selectivity of DHB was 81.1% at 25 °C and 4 h of light illumination. Furthermore, the as-prepared photocatalysts exhibited good stability after four cycles of experiment. This work provided a convenient and efficient method for the green synthesis of DHB.

Porous C3N4 nanosheet supported Au single atoms as an efficient catalyst for enhanced photoreduction of CO2 to CO

Artificial photosynthesis utilizing solar energy to convert carbon dioxide (CO2) and water (H2O) into fuels and high-value chemicals offers a promising technology for mitigating energy consumption and environmental pollution. However, the development of efficient photocatalysts with high product selectivity remains a big challenge due to the sluggish dynamic transfer of photogenerated charge carriers. Herein, porous C3N4 nanosheet supported Au single atoms photocatalyst (Au1@CN) with AuN4 coordination is fabricated via a facile “impregnation + freeze-drying” process. The as-synthesized Au1@CN exhibits efficient and stable CO2 photoreduction activity with a CO evolution rate of 0.58 μmol h−1 (amount of catalyst: 10 mg), CO selectivity of 94 %, and a turnover frequency (TOF) of 10.0 h−1 using H2O as the reductant, which exceed most previous works on C3N4-based single-atom photocatalysts for CO2 reduction. Experimental studies and density functional theory (DFT) calculations reveal that the unique Au—N4 coordination promotes the dynamic transfer of photogenerated charge carriers, facilitates the adsorption/activation of CO2 molecules and generation of *COOH intermediate, thereby significantly enhancing the CO2 photoreduction activity with high CO selectivity. This study demonstrates an effective strategy for the design of M—N4 coordinated single-atom catalyst toward efficient and selective photoreduction of CO2 to CO.