CuOx/TiO2光催化水蒸气还原CO2

以商品TiO2-P25为原料,通过浸渍法负载一定量过渡金属Cu,得到一系列不同含量的CuOx/TiO2光催化剂。利用X射线衍射（XRD）,X－射线光电子能谱（XPS）,BET,高分辨率透射镜（HRTEM）,X射线荧光光谱（XRF）和光致发光光谱（PL）等方法对催化剂进行了详细表征,在自建的光催化反应器中评价了气态水光催化还原CO2反应的活性和CH4收率。结果表明负载CuOx后的TiO2纳米材料光催化性能显著提高,其中1%CuOx/TiO2样品紫外光照72 h后,CH4生成量达到了24.86 µmol•gTi-1。同时,CuOx负载量、反应温度、反应时间等因素对CH4收率均有显著影响。     

Metal-Organic Frameworks for Photocatalytic Water Splitting and CO2 Reduction

Photocatalytic water splitting and carbon dioxide (CO₂) reduction provide promising solutions to global energy and environmental issues. In recent years, metal-organic frameworks (MOFs), a class of crystalline porous solids featuring well-defined and tailorable structures as well as high surface areas, have captured great interest toward photocatalytic water splitting and CO₂ reduction. In this review, the semiconductor-like behavior of MOFs is first discussed. We then summarize the recent advances in photocatalytic water splitting and CO₂ reduction over MOF-based materials and focus on the unique advantage of MOFs for clarifying the structure-property relationship in photocatalysis. In addition, some representative characterization techniques have been presented to unveil the photocatalytic kinetics and reaction intermediates in MOF-based systems. Finally, the challenges, and perspectives for future directions are proposed.     

Electronic Transmission Channels Promoting Charge Separation of Conjugated Polymers for Photocatalytic CO2 Reduction with Controllable Selectivity

Conjugated polymers (CPs) represent a promising platform for photocatalytic CO₂ fixation owing to their suitable band structures that meet the requirements of the reduction potential of CO₂ to value-added fuels. However, the photocatalytic performance of CPs is rather restrained by the low charge transfer efficiency. Herein, we rationally designed three CPs with a more delocalized electronic transmission channel and planar molecular structure, which are regarded to evidently reduce the exciton binding energy (E_b) and accelerate the internal charge transfer process. Besides, the assembly of suitable electron-output “tentacles” and cocatalysts on the surface of CPs could effectively facilitate interfacial electron delivery. Accordingly, the optimal P-2CN exhibits an apparent quantum yield of 4.6 % at 420 nm for photocatalytic CO₂ to CO. Further adjusting the amounts of cyano groups and cocatalysts, the CO selectivity could be obtained in the range of 0–80.5 %.     

Modulating the Reaction Configuration by Breaking the Structural Symmetry of Active Sites for Efficient Photocatalytic Reduction of Low-concentration CO2

Photocatalytic conversion of low-concentration CO₂ is considered as a promising way to simultaneously mitigate the environmental and energy issues. However, the weak CO₂ adsorption and tough CO₂ activation process seriously compromise the CO production, due to the chemical inertness of CO₂ molecule and the formed fragile metal-C/O bond. Herein, we designed and fabricated oxygen vacancy contained Co₃O₄ hollow nanoparticles on ordered macroporous N-doped carbon framework (Vo−HCo₃O₄/OMNC) towards photoreduction of low-concentration CO₂. In situ spectra and ab initio molecular dynamics simulations reveal that the constructed oxygen vacancy is able to break the local structural symmetry of Co−O−Co sites. The formation of asymmetric active site switches the CO₂ configuration from a single-site linear model to a multiple-sites bending one with a highly stable configuration, enhancing the binding and structural polarization of CO₂ molecules. As a result, Vo−HCo₃O₄/OMNC shows unprecedent activity in the photocatalytic conversion of low-concentration CO₂ (10 % CO₂/Ar) under laboratory light source or even natural sunlight, affording a syngas yield of 337.8 or 95.2 mmol g⁻¹ h⁻¹, respectively, with an apparent quantum yield up to 4.2 %.     

Ni2P纳米片用于光催化二氧化碳还原

Artificial photosynthesis is an ideal method for solar-to-chemical energy conversion, wherein solar energy is stored in the form of chemical bonds of solar fuels. In particular, the photocatalytic reduction of CO₂ has attracted considerable attention due to its dual benefits of fossil fuel production and CO₂ pollution reduction. However, CO₂ is a comparatively stable molecule and its photoreduction is thermodynamically and kinetically challenging. Thus, the photocatalytic efficiency of CO₂ reduction is far below the level of industrial applications. Therefore, development of low-cost cocatalysts is crucial for significantly decreasing the activation energy of CO₂ to achieving efficient photocatalytic CO₂ reduction. Herein, we have reported the use of a Ni₂P material that can serve as a robust cocatalyst by cooperating with a photosensitizer for the photoconversion of CO₂. An effective strategy for engineering Ni₂P in an ultrathin layered structure has been proposed to improve the CO₂ adsorption capability and decrease the CO₂ activation energy, resulting in efficient CO₂ reduction. A series of physicochemical characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM) were used to demonstrate the successful preparation of ultrathin Ni₂P nanosheets. The XRD and XPS results confirm the successful synthesis of Ni₂P from Ni(OH)₂ by a low temperature phosphidation process. According to the TEM images, the prepared Ni₂P nanosheets exhibit a 2D and near-transparent sheet-like structure, suggesting their ultrathin thickness. The AFM images further demonstrated this result and also showed that the height of the Ni₂P nanosheets is ca 1.5 nm. The photoluminescence (PL) spectroscopy results revealed that the Ni₂P material could efficiently promote the separation of the photogenerated electrons and holes in [Ru(bpy)₃]Cl₂·6H₂O. More importantly, the Ni₂P nanosheets could more efficiently promote the charge transfer and charge separation rate of [Ru(bpy)₃]Cl₂·6H₂O compared with the Ni₂P particles. In addition, the electrochemical experiments revealed that the Ni₂P nanosheets, with their high active surface area and charge conductivity, can provide more active centers for CO₂ conversion and accelerate the interfacial reaction dynamics. These results strongly suggest that the Ni₂P nanosheets are a promising material for photocatalytic CO₂ reduction, and can achieve a CO generation rate of 64.8 μmol·h^-1, which is 4.4 times higher than that of the Ni₂P particles. In addition, the XRD and XPS measurements of the used Ni₂P nanosheets after the six cycles of the photocatalytic CO₂ reduction reaction demonstrated their high stability. Overall, this study offers a new function for the 2D transition-metal phosphide catalysts in photocatalytic CO₂ reduction.     

Electronic Interactions on Platinum/(Metal-Oxide)-Based Photocatalysts Boost Selective Photoreduction of CO2 to CH4

By supporting platinum (Pt) and cadmium sulfide (CdS) nanoparticles on indium oxide (In₂O₃), we fabricated a CdS/Pt/In₂O₃ photocatalyst. Selective photoreduction of carbon dioxide (CO₂) to methane (CH₄) was achieved on CdS/Pt/In₂O₃ with electronic Pt−In₂O₃ interactions, with CH₄ selectivity reaching to 100 %, which is higher than that on CdS/Pt/In₂O₃ without electronic Pt−In₂O₃ interactions (71.7 %). Moreover, the enhancement effect of electronic Pt-(metal-oxide) interactions on selective photoreduction of CO₂ to CH₄ also occurs by using other common metal oxides, such as photocatalyst supports, including titanium oxide, gallium oxide, zinc oxide, and tungsten oxide. The electronic Pt-(metal-oxide) interactions separate photogenerated electron-hole pairs and convert CO₂ into CO₂^δ−, which can be easily hydrogenated into CH₄ via a CO₂^δ−→HCOO*→HCO*→CH*→CH₄ path, thus boosting selective photoreduction of CO₂ to CH₄. This offers a new way to achieve selective photoreduction of CO₂.     

偏硼酸锶/碳酸锶复合催化剂光催化还原CO2生成CH4的研究

采用溶胶-凝胶法制备出SrB₂O₄和SrCO₃复合催化剂(SrB₂O₄/SrCO₃). 紫外光催化还原CO₂生成CH₄的实验证明, SrB₂O₄/SrCO₃复合催化剂的光催化活性已超过SrB₂O₄和TiO₂(P25)催化剂. 利用X 射线电子衍射(XRD)谱、透射电子显微镜(TEM)和等温氮气吸附-脱附分析确定了催化剂的晶相结构、粒子尺寸和比表面积.利用紫外-可见(UV-Vis)漫反射吸收光谱、X射线光电子能谱(XPS)的价带谱和荧光光谱(PL)确定了催化剂的能带结构, 结果表明: SrB₂O₄/SrCO₃复合催化剂异质结构有利于光生载流子的分离, 从而抑制了光生电子和光生空穴的复合, 提高了光生电子和光生空穴在固液界面参加光催化反应的利用率. 因此, SrB₂O₄/SrCO₃复合催化剂的紫外光催化活性得到了有效的提高.     

An Unlocked Two-Dimensional Conductive Zn-MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production

Developing highly efficient catalytic sites for O₂ reduction to H₂O₂, while ensuring the fast injection of energetic electrons into these sites, is crucial for artificial H₂O₂ photosynthesis but remains challenging. Herein, we report a strongly coupled hybrid photocatalyst comprising polymeric carbon nitride (CN) and a two-dimensional conductive Zn-containing metal–organic framework (Zn-MOF) (denoted as CN/Zn-MOF(lc)/400; lc, low crystallinity; 400, annealing temperature in °C), in which the catalytic capability of Zn-MOF(lc) for H₂O₂ production is unlocked by the annealing-induced effects. As revealed by experimental and theoretical calculation results, the Zn sites coordinated to four O (Zn-O₄) in Zn-MOF(lc) are thermally activated to a relatively electron-rich state due to the annealing-induced local structure shrinkage, which favors the formation of a key *OOH intermediate of 2e⁻ O₂ reduction on these sites. Moreover, the annealing treatment facilitates the photoelectron migration from the CN photocatalyst to the Zn-MOF(lc) catalytic unit. As a result, the optimized catalyst exhibits dramatically enhanced H₂O₂ production activity and excellent stability under visible light irradiation.     

Engineering an Oxygen-Binding Protein for Photocatalytic CO2 Reductions in Water

While native CO₂-reducing enzymes display remarkable catalytic efficiency and product selectivity, few artificial biocatalysts have been engineered to allow understanding how the native enzymes work. To address this issue, we report cobalt porphyrin substituted myoglobin (CoMb) as a homogeneous catalyst for photo-driven CO₂ to CO conversion in water. The activity and product selectivity were optimized by varying pH and concentrations of the enzyme and the photosensitizer. Up to 2000 TON(CO) was attained at low enzyme concentrations with low product selectivity (15 %), while a product selectivity of 74 % was reached by increasing the enzyme loading but with a compromised TON(CO). The efficiency of CO generation and overall TON(CO) were further improved by introducing positively charged residues (Lys or Arg) near the active stie of CoMb, which demonstrates the value of tuning the enzyme secondary coordination sphere to enhance the CO₂-reducing performance of a protein-based photocatalytic system.     

Tailoring *H Intermediate Coverage on the CuAl2O4/CuO Catalyst for Enhanced Electrocatalytic CO2 Reduction to Ethanol

The direct electrochemical conversion of CO₂ to multi-carbon products offers a promising pathway for producing value-added chemicals using renewable electricity. However, producing ethanol remains a challenge because of the competitive ethylene formation and hydrogen evolution reactions. Herein, we propose an active hydrogen (*H)-intermediate-mediating strategy for ethanol electroproduction on a layered precursor-derived CuAl₂O₄/CuO catalyst. The catalyst delivered a Faradaic efficiency of 70 % for multi-carbon products and 41 % for ethanol at current density of 200 mA cm⁻² and exhibited a continuous 150 h durability in a flow cell. The intensive spectroscopic studies combined with theoretical calculations revealed that the in situ generated CuAl₂O₄ could tailor *H intermediate coverage and the elevated *H coverage favors the hydrogenation of the *HCCOH intermediate, accounting for the increased yield of ethanol. This work directs a pathway for enhancing ethanol electroproduction from CO₂ reduction by tailoring *H intermediate coverage.     

Metal‐Free Reduction of CO2 to Methoxyborane under Ambient Conditions through Borondiformate Formation

An abnormal N‐heterocyclic carbene (aNHC) based homogeneous catalyst has been used for the reduction of carbon dioxide to methoxyborane in the presence of a range of hydroboranes under ambient conditions and resulted in the highest turnover number of 6000. A catalytically active reaction intermediate, [aNHC‐H?9BBN(OCOH)₂] was structurally characterized and authenticated by NMR spectroscopy. A detailed mechanistic cycle of this catalytic process via borondiformate formation has been proposed from tandem experimental and computational experiments.     

CuOx/TiO2光催化水蒸气还原CO2反应研究

以商品TiO2-P25为原料,通过浸渍法负载一定量过渡金属Cu,得到一系列不同含量的CuOx/TiO2光催化剂.利用X射线衍射(XRD),X-射线光电子能谱(XPS),BET,高分辨率透射镜(HRTEM),X射线荧光光谱(XRF)和光致发光光谱(PL)等方法对催化剂进行了详细表征,在自建的光催化反应器中评价了气态水光催化还原CO2反应的活性和CH4收率.结果表明负载CuOx后的TiO2纳米材料光催化性能显著提高,其中1%CuOx/TiO2样品紫外光照72 h后,CH4生成量达到了24.86μmol.gTi-1.同时,CuOx负载量、反应温度、反应时间等因素对CH4收率均有显著影响.     

A Molecular Z-Scheme Artificial Photosynthetic System Under the Bias-Free Condition for CO2 Reduction Coupled with Two-electron Water Oxidation: Photocatalytic Production of CO/HCOOH and H2O2

Bio-inspired molecular-engineered systems have been extensively investigated for the half-reactions of H₂O oxidation or CO₂ reduction with sacrificial electron donors/acceptors. However, there has yet to be reported a device for dye-sensitized molecular photoanodes coupled with molecular photocathodes in an aqueous solution without the use of sacrificial reagents. Herein, we will report the integration of Sn^IV- or Al^III-tetrapyridylporphyrin (SnTPyP or AlTPyP) decorated tin oxide particles (SnTPyP/SnO₂ or AlTPyP/SnO₂) photoanode with the dye-sensitized molecular photocathode on nickel oxide particles containing [Ru(diimine)₃]²⁺ as the light-harvesting unit and [Ru(diimine)(CO)₂Cl₂] as the catalyst unit covalently connected and fixed within poly-pyrrole layer (RuCAT-RuC₂-PolyPyr-PRu/NiO). The simultaneous irradiation of the two photoelectrodes with visible light resulted in H₂O₂ on the anode and CO, HCOOH, and H₂ on the cathode with high Faradaic efficiencies in purely aqueous conditions without any applied bias is the first example of artificial photosynthesis with only two-electron redox reactions.     

非金属电催化剂环境条件下氮还原反应的研究进展

NH₃ plays an important role in modern society as an essential building block in the manufacture of fertilizers, aqueous ammonia, plastics, explosives, and dyes. Additionally, it is regarded as a green alternative fuel, owing to its carbon-free nature, large hydrogen capacity, high energy density, and easy transportation. The Haber-Bosch process plays a dominant role in global NH₃ synthesis; however, it involves high pressure and temperature and employs N₂ and H₂ as feeding gases, thus suffering from high energy consumption and substantial CO₂ emission. As a promising alternative to the Haber-Bosch process, electrochemical N₂ reduction enables sustainable and environmentally benign NH₃ synthesis under ambient conditions. Moreover, its applied potential is compatible with intermittent solar, wind, and other renewable energies. However, efficient electrocatalysts are required to drive N₂-to-NH₃ conversion because of the extremely inert N≡N bond. To date, significant efforts have been made to explore high-performance catalysts with high efficiency and selectivity. Generally, noble-metal catalysts exhibit efficient performance for the NRR, but their scarcity and high cost limit their large-scale application. Therefore, considerable attention has been focused on earth-abundant transition-metal (TM) catalysts that can use empty or unoccupied orbitals to accept the lone-pair electrons of N₂, while donating the abundant d-orbital electrons to the antibonding orbitals of N₂. However, these catalysts may release metal ions, leading to environmental pollution. Most of these TM electrocatalysts may also favor the formation of TM—H bonds, facilitating the hydrogen evolution reaction (HER) during the electrocatalytic reaction. Recent years have seen a surge in the exploration of metal-free catalysts (MFCs). MFCs mainly include carbon-based catalysts (CBCs) and some boron-based and phosphorus-based catalysts. Generally, CBCs exhibit a porous structure and high surface area, which are favorable for exposing more active sites and providing rich accessible channels for mass/electron transfer. Moreover, the Lewis acid sites of most metal-free compounds could accept the lone-pair electron of N₂ and adsorb N₂ molecules by forming nonmetal—N bonds, further widening their potential for electrocatalytic NRR. Compared with metal-based catalysts, the occupied orbitals of metal-free catalysts can only form covalent bonds or conjugated π bonds, hindering electron donation from the electrocatalyst to N₂ and molecular activation. In this review, we summarize the recent progress in the design and development of metal-free electrocatalysts (MFCs) for the ambient NRR, including carbon-based catalysts, boron-based catalysts, and phosphorus-based catalysts. In particular, heteroatom doping (N, O, S, B, P, F, and co-dopants), organic polymers, carbon nitride, and defect engineering are highlighted. We also discuss strategies to boost NRR performance and provide an outlook on the development perspectives of MFCs.     

g-C3N4/BiVO4复合催化剂的制备及应用于光催化还原CO2的性能

用简单的超声分散法合成了具有可见光响应的类石墨氮化碳(g-C₃N₄)/BiVO₄复合光催化剂. 采用X射线衍射(XRD), X射线光电子能谱(XPS), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 紫外-可见(UV-Vis)分光光谱, 傅里叶红外变换(FTIR)光谱, 荧光发射谱(PL)和光电流响应等技术对所制备催化剂进行相关表征. 通过可见光下(λ> 420 nm)光催化还原CO₂的性能来评价样品的光催化活性, 发现不同复合比的催化剂中, 含40% (w) g-C₃N₄的复合催化剂表现出最高的光催化活性, 其催化活性分别为纯g-C₃N₄纳米片和纯BiVO₄的催化活性的2倍和4倍.光催化活性增加的主要原因是g-C₃N₄和BiVO₄之间形成了异质结, 且相互间能级匹配, 有利于光生电子和空穴的分离.     

g-C3N4表面改性及其光催化制H2与CO2还原研究进展

Solar energy is the largest renewable energy source in the world and the primary energy source of wind energy, tidal energy, biomass energy, and fossil fuel. Photocatalysis technology is a sunlight-driven chemical reaction process on the surface of photocatalysts that can generate H₂ from water, decompose organic contaminants, and reduce CO₂ into organic fuels. As a metal-free polymeric material, graphite-like carbon nitride (g-C₃N₄) has attracted significant attention because of its special band structure, easy fabrication, and low costs. However, some bottlenecks still limit its photocatalytic performance. To date, numerous strategies have been employed to optimize the photoelectric properties of g-C₃N₄, such as element doping, functional group modification, and construction of heterojunctions. Remarkably, these modification strategies are strongly associated with the surface behavior of g-C₃N₄, which plays a key role in efficient photocatalytic performance. In this review, we endeavor to provide a comprehensive summary of g-C₃N₄-based photocatalysts prepared through typical surface modification strategies (surface functionalization and construction of heterojunctions) and elaborate their special light-excitation and response mechanism, photo-generated carrier transfer route, and surface catalytic reaction in detail under visible-light irradiation. Moreover, the potential applications of the surface-modified g-C₃N₄-based photocatalysts for photocatalytic H₂ generation and reduction of CO₂ into fuels are summarized. Finally, based on the current research, the key challenges that should be further studied and overcome are highlighted. The following are the objectives that future studies need to focus on: (1) Although considerable effort has been made to develop a surface modification strategy for g-C₃N₄, its photocatalytic efficiency is still too low to meet industrial application standards. The currently obtained solar-to‑hydrogen (STH) conversion efficiency of g-C₃N₄ for H₂ generation is approximately 2%, which is considerably lower than the commercial standards of 10%. Thus, the regulation of the surface/textural properties and electronic band structure of g-C₃N₄ should be further elucidated to improve its photocatalytic performance. (2) Significant challenges remain in the design and construction of g-C₃N₄-based S-scheme heterojunction photocatalysts by facile, low-cost, and reliable methods. To overcome the limitations of conventional heterojunctions thoroughly, a promising S-scheme heterojunction photocatalytic system was recently reported. The study further clarifies the charge transfer route and mechanism during the catalytic process. Thus, the rational design and synthesis of g-C₃N₄-based S-scheme heterojunctions will attract extensive scientific interest in the next few years in this field. (3) First-principle calculation is an effective strategy to study the optical, electrical, magnetic, and other physicochemical properties of surface strategy modified g-C₃N₄, providing important information to reveal the charge transfer path and intrinsic catalytic mechanism. As a result, density functional theory (DFT) computation will be paid increasing attention and widely applied in surface-modified g-C₃N₄-based photocatalysts.     

Thiophene-Containing Covalent Organic Frameworks for Overall Photocatalytic H2O2 Synthesis in Water and Seawater

H₂O₂ is a significant chemical widely utilized in the environmental and industrial fields, with growing global demand. Without sacrificial agents, simultaneous photocatalyzed H₂O₂ synthesis through the oxygen reduction reaction (ORR) and water oxidation reaction (WOR) dual channels from seawater is green and sustainable but still challenging. Herein, two novel thiophene-containing covalent organic frameworks (TD-COF and TT-COF) were first constructed and served as catalysts for H₂O₂ synthesis via indirect 2e⁻ ORR and direct 2e⁻ WOR channels. The photocatalytic H₂O₂ production performance can be regulated by adjusting the N-heterocycle modules (pyridine and triazine) in COFs. Notably, with no sacrificial agents, just using air and water as raw materials, TD-COF exhibited high H₂O₂ production yields of 4060 μmol h⁻¹ g⁻¹ and 3364 μmol h⁻¹ g⁻¹ in deionized water and natural seawater, respectively. Further computational mechanism studies revealed that the thiophene was the primary photoreduction unit for ORR, while the benzene ring (linked to the thiophene by the imine bond) was the central photooxidation unit for WOR. The current work exploits thiophene-containing COFs for overall photocatalytic H₂O₂ synthesis via ORR and WOR dual channels and provides fresh insight into creating innovative catalysts for photocatalyzing H₂O₂ synthesis.     

Computational Exploration of Mechanistic Avenues in Metal-Free CO2 Reduction to CO by Disilyne Bisphosphine Adduct and Phosphonium Silaylide

Recent years have seen a growing interest in metal-free CO₂ activation by silylenes, silylones, and silanones. However, compared to mononuclear silicon species, CO₂ reduction mediated by dinuclear silicon compounds, especially disilynes, has been less explored. We have carried out extensive computational investigations to explore the mechanistic avenues in CO₂ reduction to CO by donor-stabilized disilyne bisphosphine adduct ( R1^M ) and phosphonium silaylide ( R2 ) using density functional theory calculations. Theoretical calculations suggest that R1^M exhibits donor-stabilized bis(silylene) bonding features with unusual Si−Si multiple bonding. Various modes of CO₂ coordination to R1^M have been investigated and the coordination of CO₂ by the carbon center to R1^M is found to be kinetically more facile than that by oxygen involving only one or both the silicon centers. Both the theoretically predicted reaction mechanisms of R1^M and R2 -mediated CO₂ reduction reveal the crucial role of silicon-centered lone pairs in CO₂ activations and generation of key intermediates possessing enormous strain in the Si−C−O ring, which plays the pivotal role in CO extrusion.     

A Bismuth-Based Zeolitic Organic Framework with Coordination-Linked Metal Cages for Efficient Electrocatalytic CO2 Reduction to HCOOH

Zeolitic metal–organic frameworks (ZMOFs) have emerged as one of the most promsing catalysts for energy conversion, but they suffer from either weak bonding between metal-organic cubes (MOCs) that decrease their stability during catalysis processes or low activity due to inadequate active sites. In this work, through ligand-directing strategy, we successfully obtain an unprecedented bismuth-based ZMOF (Bi-ZMOF) featuring a ACO topological crystal structure with strong coordination bonding between the Bi-based cages. As a result, it enables efficient reduction of CO₂ to formic acid (HCOOH) with Faradaic efficiency as high as 91 %. A combination of in situ surface-enhanced infrared absorption spectroscopy and density functional theory calculation reveals that the Bi−N coordination contributes to facilitating charge transfer from N to Bi atoms, which stabilize the intermediate to boost the reduction efficiency of CO₂ to HCOOH. This finding highlights the importance of the coordination environment of metal active sites on electrocatalytic CO₂ reduction. We believe that this work will offer a new clue to rationally design zeolitic MOFs for catalytic reaction     

A Fully Conjugated Covalent Organic Framework with Oxidative and Reductive Sites for Photocatalytic Carbon Dioxide Reduction with Water

Constructing a powerful photocatalytic system that can achieve the carbon dioxide (CO₂) reduction half-reaction and the water (H₂O) oxidation half-reaction simultaneously is a very challenging but meaningful task. Herein, a porous material with a crystalline topological network, named viCOF-bpy-Re, was rationally synthesized by incorporating rhenium complexes as reductive sites and triazine ring structures as oxidative sites via robust −C=C− bond linkages. The charge-separation ability of viCOF-bpy-Re is promoted by low polarized π-bridges between rhenium complexes and triazine ring units, and the efficient charge-separation enables the photogenerated electron–hole pairs, followed by an intramolecular charge-transfer process, to form photogenerated electrons involved in CO₂ reduction and photogenerated holes that participate in H₂O oxidation simultaneously. The viCOF-bpy-Re shows the highest catalytic photocatalytic carbon monoxide (CO) production rate (190.6 μmol g⁻¹ h⁻¹ with about 100 % selectivity) and oxygen (O₂) evolution (90.2 μmol g⁻¹ h⁻¹) among all the porous catalysts in CO₂ reduction with H₂O as sacrificial agents. Therefore, a powerful photocatalytic system was successfully achieved, and this catalytic system exhibited excellent stability in the catalysis process for 50 hours. The structure–function relationship was confirmed by femtosecond transient absorption spectroscopy and density functional theory calculations.