Selective CO2 Reduction Research Articles

Fabrication of a Partial Encapsulation Architecture on S-Scheme Heterojunctions toward Durable Selective Photocatalytic CO2 Reduction.

It remains a challenging issue to achieve durably stable photocatalytic CO2 reduction over heterojunctions owing to their inherent structural assembly features. Herein, a unique partial encapsulation architecture is fabricated on the 3D/2D CoWO4/C3N5 heterojunction by embedding CoWO4 microspheres on C3N5 nanosheets, which achieves efficient, durable, stable, and selective photocatalytic CO2 reduction. For the optimal 5%-CoWO4/C3N5 heterojunction, the yield of selective CO2 reduction to CO is 7.70 and 3.82 times higher than those of CoWO4 and C3N5 in 4 h, respectively, and it maintains a stable CO generation rate within 20 cycles over 80 h. A series of characterization experiments and density functional theory calculations reveal that the structural stability is reinforced significantly via strong interfacial interaction owing to the unique partial encapsulation architecture fabricated on the 3D/2D CoWO4/C3N5 heterojunction, the separation efficiency of photogenerated carriers is improved by inducing a built-in electric field and triggering the S-scheme charge-transport path, and the high CO product selectivity is attributed to the much lower free energy required for the generation path of CO compared to that for CH4.

Ag-Mediated Growth of Au/Ag-Cu Ternary Heterostructures for Selective Electrochemical CO2 Reduction.

Copper (Cu)-based nanocatalysts play crucial roles in the electrochemical CO2 reduction reaction (ECO2RR) for sustainable energy resources. Particularly, Cu-based nanostructures incorporating Au and Ag are promising, offering enhanced activity, selectivity, and stability. However, precise control over the structure and composition of heterostructures remains challenging, hindering the development of highly efficient catalysts. Herein, we present a silver (Ag) transition-layer-mediated approach to synthesize ternary heterostructures with two specific morphologies, namely, Au/Ag-Cu-side and Au/Ag-Cu-tip, which exhibit different Ag-Cu interface epitaxial patterns. The two heterostructures achieve high C2 product selectivity in ECO2RR. Especially, the Au/Ag-Cu-side structure achieves 50.3% C2 selectivity with 35.5% ethanol, while the tip structure shows higher ethylene selectivity. Our study reveals the impact of the Ag layer in directing deposition sites on heterostructure growth and further facilitating the design of multicomponent Cu-based catalysts with enhanced structural integrity and ECO2RR performance.

In situ Reconstructured Alloy Nanosheets Heterojunction for Highly Selective Electrochemical CO2 Reduction to Formate.

Tin (Sn)-based materials are expected to realize efficient CO2 electroreduction into formate. Herein, we constructed a heterojunction by depositing Cu on Cu-doped SnS2 nanosheets. During the electrochemical reaction, this heterojunction evolves to a highly active phase of Cu2O@Cu6Sn5 while maintaining its two-dimensional morphology. Specifically, a partial current density of 35 mA cm-2 with an impressive faradaic efficiency of 93 % for formate production was achieved over the evolved heterojunction. In situ and ex situ experiments elucidated the formation mechanism of the Cu₂O@Cu₆Sn₅ heterojunction. Cu₆Sn₅ nanosheets were formed via a stepwise desulfurization process, while Cu₂O was generated through its reaction with hydroxyl radicals. This evolved heterojunction with a high electrochemically active surface area synergistically stabilized the *OCHO intermediate, thereby significantly enhancing the selectivity and activity. Our findings provide insight into the structural evolution process and guide the development of selective electrocatalysts for CO2 reduction.

Heterobimetallic NiFe Complex for Photocatalytic CO2 Reduction: United Efforts of NiFe Dual Sites.

Catalytic CO2 reduction poses a significant challenge for the conversion of CO2 into chemicals and fuels. Ni-Fe carbon monoxide dehydrogenase ([NiFe]-CODH) effectively mediates the reversible conversion of CO2 and CO at a nearly thermodynamic equilibrium potential, highlighting the heterobimetallic cooperation for the design of CO2 reduction catalysts. However, numerous NiFe biomimetic model complexes have realized little success in CO2 reduction catalysis, which underscores the crucial role of precise bimetallic configuration and functionality. Herein, we presented a heterobimetallic NiFe complex for the photocatalytic reduction of CO2 to CO, demonstrating significantly enhanced catalytic performance compared to the homonuclear NiNi catalyst. Photocatalytic and mechanistic investigations revealed that with the assistance of a redox-active phenanthroline ligand, NiFe achieves dual-site activation of CO2 through a pivotal intermediate, NiII(μ-CO22--κC:κO)FeII, where the Lewis acidity of the FeII site plays an important role, as corroborated in the homonuclear FeFe system. This study introduces the first heteronuclear NiFe molecular catalyst capable of efficiently catalyzing the reduction of CO2 to CO, deepening insights into heterobimetallic cooperation and offering a novel strategy for designing highly active and selective CO2 reduction catalysts.

Enhanced photocatalytic CO2 reduction to CH4 on oxygen vacancy-rich NiCo2O4 with surface pits: Synthesis, DFT calculations, and mechanistic insights

Unraveling the influence of surface microstructure in materials on their interaction with CO2 remains a critical challenge in achieving efficient and selective CO2 reduction. In this study, we report the engineering of pit structures on the NiCo2O4 surface for efficient photocatalytic reduction of CO2. Characterization results show that calcination temperature affects the distribution of surface pits and oxygen vacancy concentration. Oxygen vacancy sites accompanying surface pits facilitate the generation and movement of photogenerated electrons and holes, preventing their recombination and promoting the conversion of CO2. The CH4 yield from photocatalytic CO2 reduction reaches 52.4 μmol g−1 with the optimal pitted NiCo2O4 catalyst (PNCO2), significantly surpassing the 18.4 μmol g−1 yield of non-pitted NiCo2O4 (NPNCO). Additionally, PNCO2 improves selectivity from 81.8 % for NPNCO to 94.1 %. Density functional theory calculations show that CO2 adsorption on the PNCO2 surface is significantly enhanced as the d-band center shifts toward the Fermi level. The adsorbed CO2 combines with electrons enriched at the Ni sites at the edges of the surface pits, leading to further activation. The reduction of CO2 to intermediate products such as CHO* is analyzed based on in situ diffuse reflectance infrared Fourier transform spectroscopy, and a possible reaction pathway is proposed. This work offers fresh insights into engineering surface pit structures for the design and synthesis of catalysts for photocatalytic CO2 reduction.

Engineering hierarchical TiO2/ZnIn2S4 hybrid heterostructure with synergistic interfaces: A dual-functional S-scheme photocatalyst for efficient CO2 reduction and norfloxacin degradation

The development of multifunctional photocatalysts that can harness solar energy for both environmental remediation and energy generation is a considerable challenge in achieving sustainable development. This study introduces a dual-functional S-scheme hybrid catalyst comprising hierarchical 3D flower-like ZnIn2S4 (ZIS) microspheres embedded with TiO2 (TO) nanoparticles, synthesized via a facile in situ hydrothermal process. The unique structural and compositional synergy between ZIS and TO leverages their complementary photocatalytic properties, facilitating efficient solar energy utilization, increasing specific surface area, and enhancing CO2 adsorption capabilities. The S-scheme mechanism, confirmed by in situ-irradiated X-ray photoelectron spectroscopy and electron spin resonance spectroscopy, underlying this system promotes effective separation of photoexcited charge carriers while preserving the intrinsic strong reducibility of ZIS and high oxidizability of TO. These beneficial properties of the TO/ZIS hybrid provide a robust platform for CH4 production (75.6 μmol h−1 g−1) through selective (99.6 %) CO2 reduction over competing water reduction and achieve exceptional degradation and mineralization of the persistent antibiotic norfloxacin in water, addressing both energy and environmental challenges. Furthermore, the hybrid catalyst exhibits significant stability and recyclability, maintaining high catalytic performance across multiple cycles, thereby underscoring its practical viability. This work offers a promising blueprint for developing multifunctional photocatalysts capable of addressing critical global challenges, demonstrating the potential of hierarchical nanostructures and S-scheme charge transfer mechanisms.

Insights into the Effect of Crystal Facets and Sulfur Defects on the Product Selectivity of Various CdS Configurations for CO2 Photoreduction: A DFT Study

CO2 photoreduction into valuable hydrocarbons, such as CO, CH4, and C2H4, delivers a promising approach to address both environmental and energy challenges. Transition metal chalcogenides, particularly cadmium sulfide (CdS), have emerged as prominent candidates due to their tunable electronic properties and availability. This study delves into a comprehensive investigation of how CdS crystalline facets and sulfur-deficient surfaces modulate the product selectivity. Through employing density functional theory (DFT), we unravel the catalytic performance of various CdS crystal orientations and sulfur vacancy configurations. The results have shown that different CdS facets exhibit unique electronic characteristics and surface energetics, which influence the adsorption dynamics and reaction pathways. The introduction of sulfur vacancies further modulates the nature of active sites, leading to substantial shifts in product selectivity. A detailed investigation on the reaction mechanisms unveils that specific facets preferentially facilitate the formation of CO, while others are more conducive to the generation of hydrocarbons such as CH4 and C2H4, due to the variations in activation barriers and intermediate stabilities. These findings underscore the importance of crystal facet engineering and defect manipulation in tailoring catalyst performance thus providing valuable insights for the rational design of efficient and selective CO2 reduction metal catalysts.

Studying bimetals copper-indium for enhancing PCN photocatalytic CO2 reduction activity and selectivity mechanism

In this work, a bimetallic indium-copper-doped atomically dispersed Cu-In-PCN photocatalyst was prepared by thermal polymerization, and it exhibits remarkable photocatalytic CO2 reduction activity with CO yield of 113.56 µmol g−1 and a selectivity nearly 96 %. Additionally, experimental investigations and DFT calculations reveal the mechanisms underpinning the high performance of Cu-In-PCN catalyst, that Cu 3d and In 5p orbitals contribute to the band composition of Cu-In-PCN and reduced the bandgap, the electrons from PCN transfer to copper active sites and increasing the electron density for CO2 reduction. Furthermore, the Cu-In bimetallic lowered the free energy of COOH* intermediate, which more easily conversion to CO via dehydroxylation than PCN, Cu-PCN, and In-PCN. In situ FTIR show that the COOH* is the key intermediate in the photocatalytic reduction of CO2 to CO. This work makes up for the current shortcomings of using bimetallic-doped PCN for photocatalytic CO2 with low selectivity and unclear mechanism.

Bismuth-based photocatalysts enhanced by sulfur/oxygen vacancies for the selective reduction of carbon dioxide into methane

Reducing carbon dioxide (CO2) into methane (CH4) through photocatalysis technology can effectively decrease carbon emissions and ease the energy crisis. However, the low photocatalytic efficiency and high electron-hole recombination rates still hinder the large-scale utilization of photocatalysis. Vacancy engineering can reduce electron-hole pair complexation, however, the effects of oxygen (O) and sulfur (S) vacancies on the CO2 reduction properties of bismuth (Bi)-based photocatalysts are unclear. This study prepared different Bi-based photocatalysts, including α-Bi2O3, α-Bi2O3-X, Bi2S3, and Bi2S3-X. The introduction of vacancies was found to greatly increase the specific surface areas, effectively reduce electron-hole recombination, decrease charge transfer resistance, and enhance electron transfer, leading to enhanced CH4 production. Comparatively, Bi2S3-X has substantially demonstrated a superior efficiency in the photocatalytic conversion of CO2 to CH4 compared to Bi2S3, while α-Bi2O3-X exhibited slightly higher than α-Bi2O3. There are more S vacancies in Bi2S3-X (x=0.581) than O vacancies in α-Bi2O3-X (x=0.329), leading to its superior photocatalytic activity, with CO and CH4 production rates of 3.706 μmol·g−1·h−1 and 7.697 μmol·g−1·h−1, respectively. Moreover, the CH4 selectivity of Bi2S3-X reaches 67.50 %, which is 1.67 times that of α-Bi2O3-X. Therefore, Bi2S3-X holds great promise as a photocatalyst for CO2 reduction. This work proves that in Bi-based photocatalyst, S vacancy is more effective than O vacancy in enhancing the selective reduction of CO2 to CH4, offering a pathway for achieving selective CO2 reduction to CH4.

Transition metal-loaded C2N catalysts for selective CO2 reduction to CH4: Insights from first-principles calculations

The escalating atmospheric CO2 levels due to fossil fuel consumption pose significant environmental challenges, including the greenhouse effect and ocean acidification. Converting CO2 into valuable fuels and chemicals through electrochemical CO2RR is a promising strategy to mitigate these issues. However, the high thermodynamic stability of CO2 and the competing HER present challenges in achieving high selectivity and efficiency. This study employs first-principles calculations to investigate the performance of transition metal trimer catalysts (3TM-C2N, TM = Mn, Mo, Ru, Ti) supported on porous graphitic C2N for CO2RR to CH4. The catalysts were constructed and their stability, electronic structure, and CO2 adsorption mechanisms were systematically analyzed using DFT. The results indicate that 3TM-C2N catalysts are structurally stable, efficiently adsorb and activate CO2, and effectively suppress HER. Notably, 3Mn-C2N demonstrated optimal selectivity for CH3OH and CH4 with a limiting potential of −0.44 V, while 3Ru-C2N showed superior selectivity for the same products at limiting potentials of −0.86 V and −0.73 V, respectively. These findings provide theoretical insights for the experimental optimization of C2N-based catalysts and guide the development of efficient CO2RR electrocatalysts.

Enhancing formate yield through electrochemical CO2 reduction using BiOCl and g-C3N4 hybrid catalyst

Electrochemical carbon dioxide (CO2) reduction with bismuth-based catalysts has been widely investigated in the recent few years. This is due to bismuth’s ability to perform selective electrochemical CO2 reduction reaction (eCO2RR) to an important C1 product, the formate (HCOO–). However, boosting the performance of such catalysts is a continuous investigation. In this work, enhancing the active sites for eCO2RR is investigated by forming nanocomposites with graphitic carbon nitride (g-C3N4). BiOCl is synthesized by a simple wet-chemical approach in the presence of glycine as size-controlling agent and formed into nanocomposites, which were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Infrared (IR) Spectroscopy and N2 physisorption. Linear Sweep Voltammetry (LSV) in argon and CO2-saturated atmosphere showed higher current values in the case of CO2. Chronoamperometries (CA) were recorded at −1.06 V vs Reversible Hydrogen Electrode (RHE) for 5400 s obtaining Faradic Efficiencies (FE) varying in the range of 70–77 % depending on the nanocomposites’ composition. In fact, 52.1 wt% BiOCl/g-C3N4 formed the highest yields for formate (with also the highest rate of formation of formate) together with a minimal production of H2 and CO. The effect of nano-structuration induced by glycine, used as a size-controlling agent, to form nanoplates was crucial: microplates of BiOCl produced without glycine showed an FE of 4 %, reaching 85 % in the case of the nanoplates. Post-electrocatalysis characterization revealed the possible role of Bi2O2CO3 as the active phase for eCO2RR.

Stabilization of Cu2O catalyst via strong electronic interaction for selective electrocatalytic CO2 reduction to ethanol

While cuprous oxide (Cu2O) remains the most efficient and viable electrocatalyst for the electrochemical conversion of CO2 to ethanol, its reduction to Cu during the catalytic CO2RR process poses a barrier to its industrial application. To address this challenge, we have reported a highly stable Cu2O-based catalyst by introducing pseudo-capacitive NiCo2O4 intermediate layers. The current densities observed on the surface of the prepared NF@NiCo2O4@Cu2O remained consistent over a 15-hour stability test, demonstrating excellent durability that exceeds that of the NF@Cu2O electrode by more than 200 %. Experimental characterization and DFT analysis indicate that the exceptional stability is primarily attributed to the pseudo-capacitive NiCo2O4 interlayer with cyclic charge–discharge properties, where NiCo2O4 can capture and eliminate accumulated reduced electrons around Cu2O under strong electronic interactions and release electrons through catalytic reduction to produce hydrogen. Furthermore, the NiCo2O4@Cu2O (111) heterostructure significantly reduces the Gibbs free energy (ΔG) required for C-C coupling of *CO intermediates compared to Cu2O (111). This mechanism establishes a cyclic charge–discharge process in order to prevent reduction of Cu2O into copper monomers. As a result, NF@NiCo2O4@Cu2O demonstrates a C2H5OH faradaic efficiency of 56.9 % at −0.5 V vs. RHE, surpassing many other Cu-based catalytic electrodes. This work provides new insights into studying strong electronic interaction structures to eliminate electron enrichment at the catalytic site for stabilizing catalysts and also offers an effective strategy for designing catalysts that maintain long-term stability in industrial applications.

Dynamically Stabilizing Oxygen Atoms in Silver Catalyst for Highly Selective and Durable CO2 Reduction Reaction.

Oxide derived catalyst displays outstanding catalytic activity and selectivity in electrochemical carbon dioxide reduction reaction (CO2RR), in which, it is found that residue oxygen atoms play a pivotal role in regulating the catalyst's electronic structure and thus the CO2RR process. Unfortunately, the intrinsic thermodynamic instability of oxygen atoms in oxide derived catalyst under cathodic CO2RR potentials makes it unstable during continuous electrolysis, greatly hindering its practical industrial applications. In this work, we develop a pulsed-bias technique that is able to dynamically stabilize the residue oxygen atoms in oxide derived catalyst during electrochemical CO2RR. As a result, the oxide derived catalyst under pulsed bias exhibits super catalytic stability in catalyzing electrochemical CO2RR, while keeping excellent catalytic activity and selectivity.

In-situ construction of Bi-MOF-derived S-scheme BiOBr/CdIn2S4 heterojunction with rich oxygen vacancy for selective photocatalytic CO2 reduction using water

In this study, a highly selective MOF-BiOBr/CdIn2S4 (MOF-BiOBr/CIS) heterostructure with CdIn2S4 nanosheets grown in situ on the tubular structure derived from Bi-MOF-based BiOBr was successfully constructed using a hydrothermal method. Under simulated solar light without sacrificial or photosensitizing agents, the 20-MOF-BiOBr/CIS composite exhibited excellent photocatalytic CO2 performance, achieving production rates of 30.18 μmol‧g−1‧h−1 for CO and 1.50 μmol‧g−1‧h−1 for CH4. Compared to pure MOF-BiOBr and CdIn2S4, the CO production rates were increased by approximately 9 and 116 times, respectively. It was revealed that the 20-MOF-BiOBr/CIS composite with rich oxygen vacancy exhibited close interfacial contact and efficient charge transfer. The formation of MOF-BiOBr/CdIn2S4 heterojunction thereby provided efficient CO2 photocatalytic reduction. The CO selectivity of 20-MOF-BiOBr/CIS reached 83.4 %, and the MOF-BiOBr/CIS heterojunction exhibited good stability over multiple cycles. Furthermore, a mechanism for enhanced photocatalytic CO2 reduction by the MOF-BiOBr/CIS heterojunction was also proposed.

Ru Single Atom Dispersed Cu Nanoparticle with Dual Sites Enables Outstanding Photocatalytic CO2 Reduction.

Cu-based catalysts are promising candidates for CO2 reduction owing to the favorable energetics of Cu sites for CO2 adsorption and transformation. However, CO2 reduction involving insurmountable activation barriers and various byproducts remains a significant challenge to achieve high activity and selectivity. Herein, a photocatalyst constructed with single-Ru-site-on-Cu-nanoparticle on Bi4Ti3O12 exhibits exceptional activity and selectivity for CO2 conversion to CO. The experimental and theoretical results consistently reveal that the Ru-Cu dual sites allow the rapid transfer of photogenerated carriers for closely interacting with CO2 molecules. Importantly, the Ru-Cu dual sites exhibit extremely strong CO2 adsorption ability, and the Gibbs free energy of the rate-determining step (*CO2 to *COOH) has been significantly reduced, synergistically enhancing the entire CO2 conversion process. The optimal BTOCu2Ru0.5 photocatalyst manifests a high performance for selective reduction of CO2 to CO, yielding 10.84 μmol over 15 mg of photocatalyst in 4 h (180.67 μmol·g-1·h-1) under a 300 W Xe lamp without any photosensitizer and sacrificial reagent, outperforming all bismuth-based materials and being one of the best photocatalysts ever reported under similar reaction conditions. This work presents a strategy for the rational design of multiple metal sites toward efficient photocatalytic reduction of CO2.

Nonmetallic catalysts with high activity and selectivity for the electrocatalytic reduction of CO2 to CO

The escalating reliance on fossil fuels has intensified CO2 emissions, presenting significant environmental challenges. Electrocatalytic CO2 reduction offers a dual solution by converting CO2 into valuable chemicals, but complex mechanisms limit selectivity and efficiency. This study introduces a nitrogen-doped carbon catalyst, JGNC, synthesized via pyrolysis with predominantly pyrrolic N (8.18% N content). The JGNC catalysts achieved a current density of −770 mA·cm−2 at −1.2 V (V as. RHE) and CO selectivity of 96.55% at −1.1 V (V vs. RHE), surpassing most catalysts. In situ characterizations and theoretical analyses reveal that pyrrolic N lowers the energy barrier for CO2 reduction more effectively than pyridinic and graphitic forms, stabilizing the CO intermediate. These results highlight the potential of pyrrolic N in advancing CO2 reduction technologies, offering promising pathways for developing highly active and selective catalysts.

Selective reduction of CO2 to CO over alumina-supported catalysts of group 5 transition metal carbides

We show the applicability of a preparation method, previously reported for obtaining tailored bulk VCx catalysts, for alumina-supported G5TMCs. The characteristics of the G5TMCs/Al2O3 catalysts and their behaviour in the selective reduction of CO2 to CO through the RWGS reaction is reported. VCx/Al2O3 catalysts were active, stable and highly selective; meanwhile NbC/Al2O3 and TaC/Al2O3 were not active. VCx/Al2O3 catalysts exhibited selectivity to CO over 99.5 % at temperature above 773 K. The characteristics of alumina-supported vanadium carbide particles depended on the vanadium precursor and on the atmosphere used during the catalyst preparation. XPS characterization of VCx/Al2O3 catalysts revealed the presence of carbide species on surface before and after RWGS reaction. The catalytic behaviour of VCx/Al2O3 is analysed in the light of their characteristics and compared with bulk VCx counterparts. The most performant catalyst, VC(Pr)/Al2O3, was stable over 4 days at 723 K, with ∼100 % selectivity to CO and CO2 conversion of ∼11 %.

Ni-Electrocatalytic CO2 Reduction Toward Ethanol.

The electroreduction of CO2 offers a sustainable route to generate synthetic fuels. Cu-based catalysts have been developed to produce value-added C2+ alcohols; however, the limited understanding of complex C-C coupling and reaction pathway hinders the development of efficient CO2-to-C2+ alcohols catalysts. Herein, a Cu-free, highly mesoporous NiO catalyst, derived from the microphase separation of a block copolymer,is reported, which achieves selective CO2 reduction toward ethanol with a Faradaic efficiency of 75.2% at -0.6V versus RHE. The dense mesopores create a favorable local reaction environment with CO2-rich and H2O-deficient interfaces, suppressing hydrogen evolution and maximizing catalytic activity of NiO for CO2 reduction. Importantly, the C1-feeding experiments, in situ spectroscopy, and theoretical calculations consistently show that the direct coupling of *CO2 and *COOH is responsible for C-C bond formation on NiO, and subsequent reduction of *CO2-COOH to ethanol is energetically facile through the *COCOH and *OC2H5 pathway. The unconventional C-C coupling mechanism on NiO, in contrast to the *CO dimerization on Cu, is triggered by strong CO2 adsorption on the polarized Ni2+-O2- sites. The work not only demonstrates a highly selective Cu-free Ni-based alternative for CO2-to-C2+ alcohols transformation but also provides a new perspective on C-C coupling toward C2+ synthesis.

Highly Selective Conversion of Carbon Dioxide to Methane by Copper Single Atom Electrocatalysts.

Electrocatalytic carbon dioxide reduction into high-value chemicals is one of the important solutions to the greenhouse effect and energy crisis. However, the slow kinetic process of eight electrons requires the development of efficient catalysts to improve the yields. Single atom catalysts (SACs) with high activity and selectivity have become an emerging research frontier in the field of heterogeneous catalysis. Herein, a catalyst comprised of Cu single atoms loaded on carbon substrate (Cu-NC) is developed for highly selective electrocatalytic reduction of CO2 to methane (CH4). The optimal catalyst (Cu-NC-1-4) exhibits a faradaic efficiency (FE) of over 50 % for CH4 within a wide potential window from -1.3 V to -1.8 V (vs. RHE) and the highest FE of CH4 is up to 67.22 % at -1.6 V (vs. RHE). Meanwhile, the product selectivity of CH4 among all the carbon products reaches 93.00 %, and the activity decay can be negligible via the 70-hour-stability-test. The existence of atomic dispersed Cu-N3 sites was verified by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and X-ray absorption near edge structure (XANES). Density functional theory (DFT) calculations show that the effective adsorption of the key intermediate *CO on Cu-N3 sites prompts the generation of CH4.

M/BiOCl-(M=Pt, Pd, and Au) Boosted Selective Photocatalytic CO2 Reduction to C2 Hydrocarbons via *CHO Intermediate Manipulation.

Selective CO2 photoreduction to C2 hydrocarbons is significant but limited by the inadequate adsorption strength of the reaction intermediates and low efficiency of proton transfer. Herein, an ameliorative *CO adsorption and H2O activation strategy is realized via decorating bismuth oxychloride (BiOCl) nanostructures with different metal (Pt, Pd, and Au) species. Experimental and theoretical calculation results reveal that distinct *CO binding energies and *H acquisition abilities of the metal cocatalysts mediate the CO2 reduction activity and hydrocarbon selectivity. The relatively moderate *CO adsorption and *H supply over Pd/BiOCl endows it with the lowest free energy to generate *CHO, leading to its highest activity of hydrocarbon production. Specifically, the Pt cocatalyst can efficiently participate in H2O dissociation to deliver more *H for facilitating the protonation of the *CHO and *CHOH, thereby favoring CH4 production with 76.51% selectivity. A lower *H supply over Pd/BiOCl and Au/BiOCl results in a large energy barrier for *CHO or *CHOH protonation and thus a more thermodynamically favored OC─CHO coupling pathway, which endows them with vastly increased C2 hydrocarbon selectivity of 81.21% and 92.81%, respectively. The understanding of efficient C2 hydrocarbon production in this study sheds light on how materials can be engineered for photocatalytic CO2 reduction.