Recent Advances in Catalyst Structure and Composition Engineering Strategies for Regulating CO2 Electrochemical Reduction

Self-Assembled Controllable Cu-Based Perovskite/Calcium Oxide Hybrids with Strong Interfacial Interactions for Enhanced CH4 Electrosynthesis

Cu-based perovskite oxide catalysts show promise for CO2 electromethanation, but suffer from unsatisfactory CH4 selectivity and poor stability. Here, we report self-assembled, controllable Cu-based perovskite/calcium oxide hybrids with strongly interacting interfaces for high-performance CH4 electrosynthesis. As proof-of-concept catalysts, the La2CuO4/(CaO)x (x from 0.2 to 1.2) series has tunable CaO phase concentrations and thus controllable interface sizes. The La2CuO4 and CaO components are intimately connected at the interface, leading to strong interfacial interactions mainly manifested by marked electron transfer from Ca2+ to Cu2+. In CH4 electrosynthesis, their activity and selectivity show a volcano-type dependence on the CaO phase concentrations and are positively correlated with the interface sizes. Among them, the La2CuO4/(CaO)0.8 delivers the optimal activity and selectivity for CH4, together with good stability, much better than those of a physical-mixture counterpart and most reported Cu-based perovskite oxides. Moreover, La2CuO4/(CaO)0.8 stands out as one of the most effective Cu-based catalysts for CH4 electrosynthesis, achieving a high CH4 selectivity of 77.6% at 300 mA cm-2. Our experiments and theoretical calculations highlight the significant role of self-assembly-induced strong interfacial interactions in promoting *CO adsorption/hydrogenation, intensifying resistance to structural degradation, and consequently underpinning the achievement of such optimized performance.

Atmosphere Induces Tunable Oxygen Vacancies to Stabilize Single-Atom Copper in Ceria for Robust Electrocatalytic CO2 Reduction to CH4

Electrochemical carbon dioxide reduction (ECO2RR) shows great potential to create high-value carbon-based chemicals, while designing advanced catalysts at the atomic level remains challenging. The ECO2RR performance is largely dependent on the catalyst microelectronic structure that can be effectively modulated through surface defect engineering. Here, we provide an atmosphere-assisted low-temperature calcination strategy to prepare a series of single-atomic Cu/ceria catalysts with varied oxygen vacancy concentrations for robust electrolytic reduction of CO2 to methane. The obtained Cu/ceria catalyst under H2 environment (Cu/ceria-H2) exhibits a methane Faraday efficiency (FECH4) of 70.03 % with a turnover frequency (TOFCH4) of 9946.7 h-1 at an industrial-scale current density of 150 mA cm-2 in a flow cell. Detailed studies indicate the copious oxygen vacancies in the Cu/ceria-H2 are conducive to regulating the surface microelectronic structure with stabilized Cu+ active center. Furthermore, density functional theory calculations and operando ATR-SEIRAS demonstrate that the Cu/ceria-H2 can markedly enhance the activation of CO2, facilitate the adsorption of pivotal intermediates *COOH and *CO, thus ultimately enabling the high selectivity for CH4 production. This study presents deep insights into designing effective electrocatalysts for CO2 to CH4 conversion by controlling the surface microstructure via the reaction atmosphere.

Conductive Zeolite Supported Indium-Tin Alloy Nanoclusters for Selective and Scalable Formic Acid Electrosynthesis

Upgrading excess CO2 toward the electrosynthesis of formic acid is of significant research and commercial interest. However, simultaneously achieving high selectivity and industrially relevant current densities of CO2-to-formate conversion remains a grand challenge for practical implementations. Here, an electrically conductive zeolite support is strategically designed by implanting Sn ions into the skeleton structure of a zeolite Y, which impregnates ultrasmall In0.2Sn0.8 alloy nanoclusters into the supercages of the tailored 12-ring framework. The prominent electronic and geometric interactions between In0.2Sn0.8 nanoalloy and zeolite support lead to the delocalization of electron density that enhances orbital hybridizations between In active site and *OCHO intermediate. Thus, the energy barrier for the rate-limiting *OCHO formation step is reduced, facilitating the electrocatalytic hydrogenation of CO2 to formic acid. Accordingly, the developed zeolite electrocatalyst achieves an industrial-level partial current density of 322 mA cm-2 and remarkable Faradaic efficiency of 98.2% for formate production and stably maintains Faradaic efficiency above 93% at an industrially relevant current density for over 102 h. This work opens up new opportunities of conductive zeolite-based electrocatalysts for industrial-level formic acid electrosynthesis from CO2 electrolysis and toward practically accessible electrocatalysis and energy conversion.

Electrochemical CO2 Reduction to Multicarbon Products on Non-Copper Based Catalysts

Electrochemical CO2 reduction reaction (eCO2RR) to value-added multicarbon (C2+) products offers a promising approach for achieving carbon neutrality and storing intermittent renewable energy. Copper (Cu)-based electrocatalysts generally play the predominant role in this process. Yet recently, more and more non-Cu materials have demonstrated the capability to convert CO2 into C2+, which provides impressive production efficiency even exceeding those on Cu, and a wider variety of C2+ compounds not achievable with Cu counterparts. This motivates us to organize the present review to make a timely and tutorial summary of recent progresses on developing non-Cu based catalysts for CO2-to-C2+. We begin by elucidating the reaction pathways for C2+ formation, with an emphasis on the unique C-C coupling mechanisms in non-Cu electrocatalysts. Subsequently, we summarize the typical C2+-involved non-Cu catalysts, including ds-, d- and p-block metals, as well as metal-free materials, presenting the state-of-the-art design strategies to enhance C2+ efficiency. The system upgrading to promote C2+ productivity on non-Cu electrodes covering microbial electrosynthesis, electrolyte engineering, regulation of operational conditions, and synergistic co-electrolysis, is highlighted as well. Our review concludes with an exploration of the challenges and future opportunities in this rapidly evolving field.

Stabilizing the oxidation state of catalysts for effective electrochemical carbon dioxide conversion

In the electrocatalytic CO2 reduction reaction (CO2RR), metal catalysts with an oxidation state generally demonstrate more favorable catalytic activity and selectivity than their corresponding metallic counterparts. However, the persistence of oxidative metal sites under reductive potentials is challenging since the transition to metallic states inevitably leads to catalytic degradation. Herein, a thorough review of research on oxidation-state stabilization in the CO2RR is presented, starting from fundamental concepts and highlighting the importance of oxidation state stabilization while revealing the relevance of dynamic oxidation states in product distribution. Subsequently, the functional mechanisms of various oxidation-state protection strategies are explained in detail, and in situ detection techniques are discussed. Finally, the prevailing and prospective challenges associated with oxidation-state protection research are discussed, identifying innovative opportunities for mechanistic insights, technology upgrades, and industrial platforms to enable the commercialization of the CO2RR.

Tuning hydrogen bond network connectivity in the electric double layer with cations

Hydrogen bond (H-bond) network connectivity in electric double layers (EDLs) is of paramount importance for interfacial HER/HOR electrocatalytic processes. However, it remains unclear whether the cation-specific effect on H-bond network connectivity in EDLs exists. Herein, we report simulation evidence from ab initio molecular dynamics that cations at Pt(111)/water interfaces can tune the structure and the connectivity of H-bond networks in EDLs. As the surface charge density σ becomes more negative, we show that the connectivity of the H-bond networks in EDLs of the Na+ and Ca2+ systems decreases markedly; in stark contrast, the connectivity of the H-bond networks in EDLs of the Mg2+ system increases slightly. Further analysis revealed that the interplay between the hydration of cations and the interfacial water structure plays a key role in the connectivity of H-bond networks in EDLs. These findings highlight the key roles of cations in EDLs and electrocatalysis.

Superexchange-stabilized long-distance Cu sites in rock-salt-ordered double perovskite oxides for CO2 electromethanation

Cu-oxide-based catalysts are promising for CO2 electroreduction (CO2RR) to CH4, but suffer from inevitable reduction (to metallic Cu) and uncontrollable structural collapse. Here we report Cu-based rock-salt-ordered double perovskite oxides with superexchange-stabilized long-distance Cu sites for efficient and stable CO2-to-CH4 conversion. For the proof-of-concept catalyst of Sr2CuWO6, its corner-linked CuO6 and WO6 octahedral motifs alternate in all three crystallographic dimensions, creating sufficiently long Cu-Cu distances (at least 5.4 Å) and introducing marked superexchange interaction mainly manifested by O-anion-mediated electron transfer (from Cu to W sites). In CO2RR, the Sr2CuWO6 exhibits significant improvements (up to 14.1 folds) in activity and selectivity for CH4, together with well boosted stability, relative to a physical-mixture counterpart of CuO/WO3. Moreover, the Sr2CuWO6 is the most effective Cu-based-perovskite catalyst for CO2 methanation, achieving a remarkable selectivity of 73.1% at 400 mA cm-2 for CH4. Our experiments and theoretical calculations highlight the long Cu-Cu distances promoting *CO hydrogenation and the superexchange interaction stabilizing Cu sites as responsible for the superb performance.

Integrating Host Design and Tailored Electronic Effects of Yolk-Shell Zn-Mn Diatomic Sites for Efficient CO2 Electroreduction

Modulating the surface and spatial structure of the host is associated with the reactivity of the active site, and also enhances the mass transfer effect of the CO2 electroreduction process (CO2 RR). Herein, we describe the development of two-step ligand etch-pyrolysis to access an asymmetric dual-atomic-site catalyst (DASC) composed of a yolk-shell carbon framework (Zn1 Mn1 -SNC) derived from S,N-coordinated Zn-Mn dimers anchored on a metal-organic framework (MOF). In Zn1 Mn1 -SNC, the electronic effects of the S/N-Zn-Mn-S/N configuration are tailored by strong interactions between Zn-Mn dual sites and co-coordination with S/N atoms, rendering structural stability and atomic distribution. In an H-cell, the Zn1 Mn1 -SNC DASC shows a low onset overpotential of 50 mV and high CO Faraday efficiency of 97 % with a low applied overpotential of 343 mV, thus outperforming counterparts, and in a flow cell, it also reaches a high current density of 500 mA cm-2 at -0.85 V, benefitting from the high structure accessibility and active dual sites. DFT simulations showed that the S,N-coordinated Zn-Mn diatomic site with optimal adsorption strength of COOH* lowers the reaction energy barrier, thus boosting the intrinsic CO2 RR activity on DASC. The structure-property correlation found in this study suggests new ideas for the development of highly accessible atomic catalysts.

A replacement strategy for regulating local environment of single-atom Co-SxN4-x catalysts to facilitate CO2 electroreduction

The performances of single-atom catalysts are governed by their local coordination environments. Here, a thermal replacement strategy is developed for the synthesis of single-atom catalysts with precisely controlled and adjustable local coordination environments. A series of Co-SxN4-x (x = 0, 1, 2, 3) single-atom catalysts are successfully synthesized by thermally replacing coordinated N with S at elevated temperature, and a volcano relationship between coordinations and catalytic performances toward electrochemical CO2 reduction is observed. The Co-S1N3 catalyst has the balanced COOH*and CO* bindings, and thus locates at the apex of the volcano with the highest performance toward electrochemical CO2 reduction to CO, with the maximum CO Faradaic efficiency of 98 ± 1.8% and high turnover frequency of 4564 h-1 at an overpotential of 410 mV tested in H-cell with CO2-saturated 0.5 M KHCO3, surpassing most of the reported single-atom catalysts. This work provides a rational approach to control the local coordination environment of the single-atom catalysts, which is important for further fine-tuning the catalytic performance.

Impact of Anodic Oxidation Reactions in the Performance Evaluation of High-Rate CO2 /CO Electrolysis

The membrane-electrode assembly (MEA) approach appears to be the most promising technique to realize the high-rate CO2 /CO electrolysis, however there are major challenges related to the crossover of ions and liquid products from cathode to anode via the membrane and the concomitant anodic oxidation reactions (AORs). In this perspective, by combining experimental and theoretical analyses, several impacts of anodic oxidation of liquid products in terms of performance evaluation are investigated. First, the crossover behavior of several typical liquid products through an anion-exchange membrane is analyzed. Subsequently, two instructive examples (introducing formate or ethanol oxidation during electrolysis) reveals that the dynamic change of the anolyte (i.e., pH and composition) not only brings a slight shift of anodic potentials (i.e., change of competing reactions), but also affects the chemical stability of the anode catalyst. Anodic oxidation of liquid products can also cause either over- or under-estimation of the Faradaic efficiency, leading to an inaccurate assessment of overall performance. To comprehensively understand fundamentals of AORs, a theoretical guideline with hierarchical indicators is further developed to predict and regulate the possible AORs in an electrolyzer. The perspective concludes by giving some suggestions on rigorous performance evaluations for high-rate CO2 /CO electrolysis in an MEA-based setup.

Catalyst-Free Carbon Dioxide Conversion in Water Facilitated by Pulse Discharges

By inducing CO2-pulsed discharges within microchannel bubbles and regulating thus-forming plasma microbubbles, we observe high-performance, catalyst-free coformation of hydrogen peroxide (H2O2) and oxalate directly from CO2 and water. With isotope-labeled C18O2 as the feedstock, peaks of H218O16O and H216O2 observed by ex situ surface-enhanced Raman spectra indicate that single-atom oxygen (O) from CO2 dissociations and H2O-derived OH radicals both contribute to H2O2 formation. The global plasma chemistry modeling suggests that high-density, energy-intense electron supply enables high-density CO2- (aq) and HCO2- (aq) formation and their subsequent coupling to produce oxalate. The enhanced solvation of CO2, facilitated by the efficient transport of CxOy ionic species and CO, is demonstrated as a crucial benefit of spark discharges interacting with water at the bubble interface. We expect this plasma microbubble approach to provide a novel power-to-chemical avenue to convert CO2 into valuable H2O2 and oxalic acid platform chemicals, thus leveraging renewable energy resources.

Advanced Catalyst Design and Reactor Configuration Upgrade in Electrochemical Carbon Dioxide Conversion

Electrochemical carbon dioxide reduction reaction (CO2 RR) driven by renewable energy shows great promise in mitigating and potentially reversing the devastating effects of anthropogenic climate change and environmental degradation. The simultaneous synthesis of energy-dense chemicals can meet global energy demand while decoupling emissions from economic growth. However, the development of CO2 RR technology faces challenges in catalyst discovery and device optimization that hinder their industrial implementation. In this contribution, a comprehensive overview of the current state of CO2 RR research is provided, starting with the background and motivation for this technology, followed by the fundamentals and evaluated metrics. Then the underlying design principles of electrocatalysts are discussed, emphasizing their structure-performance correlations and advanced electrochemical assembly cells that can increase CO2 RR selectivity and throughput. Finally, the review looks to the future and identifies opportunities for innovation in mechanism discovery, material screening strategies, and device assemblies to move toward a carbon-neutral society.

Stability Issues in Electrochemical CO2 Reduction: Recent Advances in Fundamental Understanding and Design Strategies

Electrochemical CO2 reduction reaction (CO2 RR) offers a promising approach to close the anthropogenic carbon cycle and store intermittent renewable energy in fuels or chemicals. On the path to commercializing this technology, achieving the long-term operation stability is a central requirement but still confronts challenges. This motivates to organize the present review to systematically discuss the stability issue of CO2 RR. This review starts from the fundamental understanding on the destabilization mechanisms of CO2 RR, with focus on the degradation of electrocatalyst and change of reaction microenvironment during continuous electrolysis. Subsequently, recent efforts on catalyst design to stabilize the active sites are summarized, where increasing atomic binding strength to resist surface reconstruction is highlighted. Next, the optimization of electrolysis system to enhance the operation stability by maintaining reaction microenvironment especially mitigating flooding and carbonate problems is demonstrated. The manipulation on operation conditions also enables to prolong CO2 RR lifespan through recovering catalytically active sites and mass transport process. This review finally ends up by indicating the challenges and future opportunities.

Electrocatalytic CO2 Reduction to Ethylene: From Advanced Catalyst Design to Industrial Applications

The value-added chemicals, monoxide, methane, ethylene, ethanol, ethane, and so on, can be efficiently generated through the electrochemical CO2 reduction reaction (eCO2 RR) when equipped with suitable catalysts. Among them, ethylene is particularly important as a chemical feedstock for petrochemical manufacture. However, despite its high Faradaic efficiency achievable at relatively low current densities, the substantial enhancement of ethylene selectivity and stability at industrial current densities poses a formidable challenge. To facilitate the industrial implementation of eCO2 RR for ethylene production, it is imperative to identify key strategies and potential solutions through comprehending the recent advancements, remaining challenges, and future directions. Herein, the latest and innovative catalyst design strategies of eCO2 RR to ethylene are summarized and discussed, starting with the properties of catalysts such as morphology, crystalline, oxidation state, defect, composition, and surface engineering. The review subsequently outlines the related important state-of-the-art technologies that are essential in driving forward eCO2 RR to ethylene into practical applications, such as CO2 capture, product separation, and downstream reactions. Finally, a greenhouse model that integrates CO2 capture, conversion, storage, and utilization is proposed to present an ideal perspective direction of eCO2 RR to ethylene.

CO2 electro-reduction reaction via a two-dimensional TM@TAP single-atom catalyst

In this study, the possibility of using TM atom anchored monolayer TAP as a class of electrocatalysts (TM@TAP, TM = 3d and 4d transition metal) toward carbon dioxide reduction reaction (CO2RR) was systematically investigated using first-principles calculations. During screening potential catalysts, the possibility that H and OH block the active site was considered. Then, the reaction mechanisms of screened catalysts were explored in detail. Interestingly, the different catalysts demonstrated different selectivities. Our results demonstrate that Cr@TAP, Zn@TAP, Mo@TAP, and Cd@TAP are selective toward the HCOOH product with a limiting potential in the range of -0.33 to -0.71 V. Mn@TAP and Rh@TAP promote CO production. The reduction products of Fe@TAP and Co@TAP were CH3OH and HCHO, respectively. Tc@TAP and Ru@TAP can catalyze CO2 to yield the deep reduction product, i.e. CH4. Among these catalysts, Cr@TAP and Rh@TAP are highly active due to their lower limiting potentials of -0.33 V and -0.28 V, respectively, and Fe@TAP can promote the production of the desired CH3OH with a limiting potential of -0.51 V, which allow them to be promising electrocatalysts for the CO2RR. We hope that our study will provide some insights into the rational design of electrocatalysts and useful guidance for experimental researchers.

Hybrid Data-Driven Discovery of High-Performance Silver Selenide-Based Thermoelectric Composites

Optimizing material compositions often enhances thermoelectric performances. However, the large selection of possible base elements and dopants results in a vast composition design space that is too large to systematically search using solely domain knowledge. To address this challenge, a hybrid data-driven strategy that integrates Bayesian optimization (BO) and Gaussian process regression (GPR) is proposed to optimize the composition of five elements (Ag, Se, S, Cu, and Te) in AgSe-based thermoelectric materials. Data is collected from the literature to provide prior knowledge for the initial GPR model, which is updated by actively collected experimental data during the iteration between BO and experiments. Within seven iterations, the optimized AgSe-based materials prepared using a simple high-throughput ink mixing and blade coating method deliver a high power factor of 2100 µW m-1 K-2 , which is a 75% improvement from the baseline composite (nominal composition of Ag2 Se1 ). The success of this study provides opportunities to generalize the demonstrated active machine learning technique to accelerate the development and optimization of a wide range of material systems with reduced experimental trials.

Cation-Radius-Controlled Sn-O Bond Length Boosting CO2 Electroreduction over Sn-Based Perovskite Oxides

Despite the intriguing potential shown by Sn-based perovskite oxides in CO2 electroreduction (CO2 RR), the rational optimization of their CO2 RR properties is still lacking. Here we report an effective strategy to promote CO2 -to-HCOOH conversion of Sn-based perovskite oxides by A-site-radius-controlled Sn-O bond lengths. For the proof-of-concept examples of Ba1-x Srx SnO3 , as the A-site cation average radii decrease from 1.61 to 1.44 Å, their Sn-O bonds are precisely shortened from 2.06 to 2.02 Å. Our CO2 RR measurements show that the activity and selectivity of these samples for HCOOH production exhibit volcano-type trends with the Sn-O bond lengths. Among these samples, the Ba0.5 Sr0.5 SnO3 features the optimal activity (753.6 mA ⋅ cm-2 ) and selectivity (90.9 %) for HCOOH, better than those of the reported Sn-based oxides. Such optimized CO2 RR properties could be attributed to favorable merits conferred by the precisely controlled Sn-O bond lengths, e.g., the regulated band center, modulated adsorption/activation of intermediates, and reduced energy barrier for *OCHO formation. This work brings a new avenue for rational design of advanced Sn-based perovskite oxides toward CO2 RR.

Self-Accelerating Effect in a Covalent-Organic Framework with Imidazole Groups Boosts Electroreduction of CO2 to CO

Solvent effect plays an important role in catalytic reaction, but there is little research and attention on it in electrochemical CO2 reduction reaction (eCO2 RR). Herein, we report a stable covalent-organic framework (denoted as PcNi-im) with imidazole groups as a new electrocatalyst for eCO2 RR to CO. Interestingly, compared with neutral conditions, PcNi-im not only showed high Faraday efficiency of CO product (≈100 %) under acidic conditions (pH ≈ 1), but also the partial current density was increased from 258 to 320 mA cm-2 . No obvious degradation was observed over 10 hours of continuous operation at the current density of 250 mA cm-2 . The mechanism study shows that the imidazole group on the framework can be protonated to form an imidazole cation in acidic media, hence reducing the surface work function and charge density of the active metal center. As a result, CO poisoning effect is weakened and the key intermediate *COOH is also stabilized, thus accelerating the catalytic reaction rate.

Interfacial Assembly of Nanocrystals on Nanofibers with Strong Interaction for Electrocatalytic Nitrate Reduction

One-dimensional fiber architecture serves as an excellent catalyst support. The orderly arrangement of active materials on such a fiber substrate can enhance catalytic performance by exposing more active sites and facilitating mass diffusion; however, this remains a challenge. We developed an interfacial assembly strategy for the orderly distribution of metal nanocrystals on different fiber substrates to optimize their electrocatalytic performance. Using electrochemical nitrate reduction reaction (NO3 - RR) as a representative reaction, the iron-based nanofibers (Fe/NFs) assembly structure achieved an excellent nitrate removal capacity of 2317 mg N/g Fe and N2 selectivity up to 97.2 %. This strategy could promote the rational design and synthesis of fiber-based electrocatalysts.

MXene-Regulated Metal-Oxide Interfaces with Modified Intermediate Configurations Realizing Nearly 100% CO2 Electrocatalytic Conversion

Electrocatalytic CO2 reduction via renewable electricity provides a sustainable way to produce valued chemicals, while it suffers from low activity and selectivity. Herein, we constructed a novel catalyst with unique Ti3 C2 Tx MXene-regulated Ag-ZnO interfaces, undercoordinated surface sites, as well as mesoporous nanostructures. The designed Ag-ZnO/Ti3 C2 Tx catalyst achieves an outstanding CO2 conversion performance of a nearly 100% CO Faraday efficiency with high partial current density of 22.59 mA cm-2 at -0.87 V versus reversible hydrogen electrode. The electronic donation of Ag and up-shifted d-band center relative to Fermi level within MXene-regulated Ag-ZnO interfaces contributes the high selectivity of CO. The CO2 conversion is highly correlated with the dominated linear-bonded CO intermediate confirmed by in situ infrared spectroscopy. This work enlightens the rational design of unique metal-oxide interfaces with the regulation of MXene for high-performance electrocatalysis beyond CO2 reduction.

Spatiotemporal Mapping of Local Heterogeneities during Electrochemical Carbon Dioxide Reduction

The activity and selectivity of a copper electrocatalyst during the electrochemical CO₂ reduction reaction (eCO₂RR) are largely dominated by the interplay between local reaction environment, the catalyst surface, and the adsorbed intermediates. In situ characterization studies have revealed many aspects of this intimate relationship between surface reactivity and adsorbed species, but these investigations are often limited by the spatial and temporal resolution of the analytical technique of choice. Here, Raman spectroscopy with both space and time resolution was used to reveal the distribution of adsorbed species and potential reaction intermediates on a copper electrode during eCO₂RR. Principal component analysis (PCA) of the in situ Raman spectra revealed that a working electrocatalyst exhibits spatial heterogeneities in adsorbed species, and that the electrode surface can be divided into CO-dominant (mainly located at dendrite structures) and C-C dominant regions (mainly located at the roughened electrode surface). Our spectral evaluation further showed that in the CO-dominant regions, linear CO was observed (as characterized by a band at ∼2090 cm^-1), accompanied by the more classical Cu-CO bending and stretching vibrations located at ∼280 and ∼360 cm^-1, respectively. In contrast, in the C-C directing region, these three Raman bands are suppressed, while at the same time a band at ∼495 cm^-1 and a broad Cu-CO band at ∼2050 cm^-1 dominate the Raman spectra. Furthermore, PCA revealed that anodization creates more C-C dominant regions, and labeling experiments confirmed that the 495 cm^-1 band originates from the presence of a Cu-C intermediate. These results indicate that a copper electrode at work is very dynamic, thereby clearly displaying spatiotemporal heterogeneities, and that in situ micro-spectroscopic techniques are crucial for understanding the eCO₂RR mechanism of working electrocatalyst materials.

Enriching Reaction Intermediates in Multishell Structured Copper Catalysts for Boosted Propanol Electrosynthesis from Carbon Monoxide

Fine-tuned catalysts that alter the diffusion kinetics of reaction intermediates is of great importance for achieving high-performance multicarbon (C₂₊) product generation in carbon monoxide (CO) reduction. Herein, we conduct a structural design based on Cu₂O nanoparticles and present an effective strategy for enhancing propanol electrosynthesis from CO. The electrochemical characterization, operando Raman monitoring, and finite-element method simulations reveal that the multishell structured catalyst can realize the enrichment of C₁ and C₂ intermediates by nanoconfinement space, leading to the possibility of further coupling. Consequently, the multishell copper catalyst realizes a high Faraday efficiency of 22.22 ± 0.38% toward propanol at the current density of 50 mA cm^-2.

CuC(O) Interfaces Deliver Remarkable Selectivity and Stability for CO2 Reduction to C2+ Products at Industrial Current Density of 500 mA cm-2

The electrocatalytic CO₂ reduction reaction (CO₂ RR) is an attractive technology for CO₂ valorization and high-density electrical energy storage. Achieving a high selectivity to C₂₊ products, especially ethylene, during CO₂ RR at high current densities (>500 mA cm^-2 ) is a prized goal of current research, though remains technically very challenging. Herein, it is demonstrated that the surface and interfacial structures of Cu catalysts, and the solid-gas-liquid interfaces on gas-diffusion electrode (GDE) in CO₂ reduction flow cells can be modulated to allow efficient CO₂ RR to C₂₊ products. This approach uses the in situ electrochemical reduction of a CuO nanosheet/graphene oxide dots (CuOC(O)) hybrid. Owing to abundant CuOC interfaces in the CuOC(O) hybrid, the CuO nanosheets are topologically and selectively transformed into metallic Cu nanosheets exposing Cu(100) facets, Cu(110) facets, Cu[n(100) × (110)] step sites, and Cu⁺ /Cu⁰ interfaces during the electroreduction step, the faradaic efficiencie (FE) to C₂₊ hydrocarbons was reached as high as 77.4% (FE_ethylene  ≈ 60%) at 500 mA cm^-2 . In situ infrared spectroscopy and DFT simulations demonstrate that abundant Cu⁺ species and Cu⁰ /Cu⁺ interfaces in the reduced CuOC(O) catalyst improve the adsorption and surface coverage of *CO on the Cu catalyst, thus facilitating CC coupling reactions.

Mechanism of Cations Suppressing Proton Diffusion Kinetics for Electrocatalysis

Proton transfer is crucial for electrocatalysis. Accumulating cations at electrochemical interfaces can alter the proton transfer rate and then tune electrocatalytic performance. However, the mechanism for regulating proton transfer remains ambiguous. Here, we quantify the cation effect on proton diffusion in solution by hydrogen evolution on microelectrodes, revealing the rate can be suppressed by more than 10 times. Different from the prevalent opinions that proton transport is slowed down by modified electric field, we found water structure imposes a more evident effect on kinetics. FTIR test and path integral molecular dynamics simulation indicate that proton prefers to wander within the hydration shell of cations rather than to hop rapidly along water wires. Low connectivity of water networks disrupted by cations corrupts the fast-moving path in bulk water. This study highlights the promising way for regulating proton kinetics via a modified water structure.

Boosting large-current-density water oxidation activity and stability by phytic acid-assisted rapid electrochemical corrosion

Corrosion engineering is an efficient strategy to achieve durable oxygen evolution reaction (OER) catalysts at high current densities beyond 500 mA cm^-2. However, the spontaneous electrochemical corrosion has a slow reaction rate, and most of them need to add large amounts of salts (such as NaCl) to accelerate the corrosion process. In this report, a novel and effective phytic acid (PA)-assisted in situ electrochemical corrosion strategy is demonstrated to accelerate the the corrosion process and form bimetallic active catalysts to show excellent OER performance at large current densities. In situ rapid electrochemical corrosion of nickel foam substrate and PA ligands etching realize localized high concentrations of Ni and Fe ions. High concentrations of metal ions will combine with hydroxyl to effectively form defects-enriched NiFe layered double hydroxides porous nanosheets tightly anchoring on the underneath substrate. Remarkably, the activated electrode exhibits excellent OER catalytic activities with ultralow overpotentials of 289 and 315 mV to reach high current densities of 500 and 1000 mA cm^-2, respectively. When coupled with Ni-Mo-N hydrogen evolution reaction catalysts, the two-electrode cell merely requires 1.87 V to deliver 1000 mA cm^-2. The ligands-assisted rapid electrochemical corrosion strategy provides a fresh perspective for facile, cost-effective, and scale-up production of superior OER catalysts at large current densities.

One-Step Phase Separation for Core-Shell Carbon@Indium Oxide@Bismuth Microspheres with Enhanced Activity for CO2 Electroreduction to Formate

It is a substantial challenge to construct electrocatalysts with high activity, good selectivity, and long-term stability for electrocatalytic reduction of carbon dioxide to formic acid. Herein, bismuth and indium species are innovatively integrated into a uniform heterogeneous spherical structure by a neoteric quasi-microemulsion method, and a novel C@In₂ O₃ @Bi₅₀ core-shell structure is constructed through a subsequent one-step phase separation strategy due to melting point difference and Kirkendall effect with the nano-limiting effect of the carbon structure. This core-shell C@In₂ O₃ @Bi₅₀ catalyst can selectively reduce CO₂ to formate with high selectivity (≈90% faradaic efficiency), large partial current density (24.53 mA cm^-2 at -1.36 V), and long-term stability (up to 14.5 h), superior to most of the Bi-based catalysts. The hybrid Bi/In₂ O₃ interfaces of core-shell C@In₂ O₃ @Bi will stabilize the key intermediate HCOO* and suppress CO poisoning, benefiting the CO₂ RR selectivity and stability, while the internal cavity of core-shell structure will improve the reaction kinetics because of the large specific surface area and the enhancement of ion shuttle and electron transfer. Furthermore, the nano-limited domain effect of outmost carbon prevent active components from oxidation and agglomeration, helpful for stabilizing the catalyst. This work offers valuable insights into core-shell structure engineering to promote practical CO₂ conversion technology.

Grain Boundary-Rich Copper Nanocatalysts Generated from Metal-Organic Framework Nanoparticles for CO2 -to-C2+ Electroconversion

Due to severe contemporary energy issues, generating C₂₊ products from electrochemical carbon dioxide reduction reactions (eCO₂ RRs) gains much interest. It is known that the catalyst morphology and active surface structures are critical for product distributions and current densities. Herein, a synthetic protocol of nanoparticle morphology on copper metal-organic frameworks (n-Cu MOFs) is developed by adjusting growth kinetics with termination ligands. Nanoscale copper oxide aggregates composed of small particulates are yielded via calcining the Cu-MOF nanoparticles at a specific temperature. The resulting nanosized MOF-derived catalyst (n-MDC) exhibits Faradaic efficiencies toward ethylene and C₂₊ products of 63% and 81% at -1.01 V versus reversible hydrogen electrode (RHE) in neutral electrolytes. The catalyst also shows prolonged stability for up to 10 h. A partial current density toward C₂₊ products is significantly boosted to -255 mA cm^-2 in an alkaline flow cell system. Comprehensive analyses reveal that the nanoparticle morphology of pristine Cu MOFs induces homogeneous decomposition of organic frameworks at a lower calcination temperature. It leads to evolving grain boundaries in a high density and preventing severe agglomeration of copper domains, the primary factors for improving eCO₂ RR activity toward C₂₊ production.

Toward Effective CO2 Reduction in an Acid Medium: Electrocatalysis at Cu2O-Derived Polycrystalline Cu Sites Immobilized within the Network of WO3 Nanowires

A hybrid catalytic system composed of copper (I)-oxide-derived copper nanocenters immobilized within the network of tungsten oxide nanowires has exhibited electrocatalytic activity toward CO₂ reduction in an acid medium (0.5 mol dm^-3 H₂SO₄). The catalytic system facilitates conversion of CO₂ to methanol and is fairly selective with respect to the competing hydrogen evolution. The preparative procedure has involved voltammetric electroreduction of Cu₂O toward the formation and immobilization of catalytic Cu sites within the hexagonal structures of WO₃ nanowires which are simultaneously partially reduced to mixed-valence hydrogen tungsten (VI, V) oxide bronzes, H _x WO₃, coexisting with sub-stoichiometric tungsten (VI, IV) oxides, WO_3-y . After the initial loss of Cu through its dissolution to Cu²⁺ during positive potential scanning up to 1 V (vs RHE), the remaining copper is not electroactive and seems to be trapped within in the network of hexagonal WO₃. Using the ultramicroelectrode-based probe, evidence has also been provided that partially reduced nonstoichiometric tungsten oxides induce reduction of CO₂ to the CO-type reaction intermediates. The chronocoulometric data are consistent with the view that existence of copper sites dispersed in WO₃ improves electron transfers and charge propagation within the hybrid catalytic layer. The enhanced tolerance of the catalyst to the competitive hydrogen evolution during CO₂R should be explained in terms of the ability of H _x WO₃ to consume protons and absorb hydrogen as well as to shift the proton discharge at Cu toward more negative potentials. However, the capacity of WO₃ to interact with catalytic copper and to adsorb CO-type reaction intermediates is expected to facilitate removal of the poisoning CO-type adsorbates from Cu sites.

CO2 electroreduction to multicarbon products in strongly acidic electrolyte via synergistically modulating the local microenvironment

Electrochemical CO₂ reduction to multicarbon products faces challenges of unsatisfactory selectivity, productivity, and long-term stability. Herein, we demonstrate CO₂ electroreduction in strongly acidic electrolyte (pH ≤ 1) on electrochemically reduced porous Cu nanosheets by combining the confinement effect and cation effect to synergistically modulate the local microenvironment. A Faradaic efficiency of 83.7 ± 1.4% and partial current density of 0.56 ± 0.02 A cm^-2, single-pass carbon efficiency of 54.4%, and stable electrolysis of 30 h in a flow cell are demonstrated for multicarbon products in a strongly acidic aqueous electrolyte consisting of sulfuric acid and KCl with pH ≤ 1. Mechanistically, the accumulated species (e.g., K⁺ and OH^-) on the Helmholtz plane account for the selectivity and activity toward multicarbon products by kinetically reducing the proton coverage and thermodynamically favoring the CO₂ conversion. We find that the K⁺ cations facilitate C-C coupling through local interaction between K⁺ and the key intermediate *OCCO.

Perovskite-Socketed Sub-3 nm Copper for Enhanced CO2 Electroreduction to C2

In situ socketing metal nanoparticles onto perovskite oxides has shown great potential in heterogeneous catalysis, but its employment in boosting ambient CO₂ electroreduction (CER) is unexplored. Here, a CER catalyst of perovskite-socketed sub-3 nm Cu equipped with strong metal-support interactions (SMSIs) is constructed to promote efficient and stable CO₂ -to-C₂₊ conversion. For such a catalyst, plentiful sub-3 nm ellipsoid Cu particles are homogeneously and epitaxially anchored on the perovskite backbones, with concomitant creation of significant SMSIs. These SMSIs are able to not only modulate electronic structure of active Cu and facilitate adsorption/activation of key intermediates, but also to strengthen perovskite-Cu adhesion and intensify resistance to structural degradation. Beneficial from these advantageous merits, when evaluated in CER, it performs comparably to or better than most reported Cu-based heteronanostructures. Relative to a physical-mixture counterpart, it features marked improvements (up to 6.2 folds) in activity and selectivity for C₂₊ , together with greatly boosted stability (>80 h). This work gives a new avenue to rationally design more advanced Cu-based heteronanostructures for CER.

Oxidation State Modulation of Bimetallic Tin-Copper Oxide Nanotubes for Selective CO2 Electroreduction to Formate

In this work, the oxidation state of Sn and Cu active sites for CO₂ electroreduction via constructing a Sn-Cun bimetallic oxide composite with a nanotube structure (SnCu-CNS) is successfully modulated. Compared to a single SnO₂ or CuO_x component, the SnCu-CNS composite holds reinforced electronegativity to generate unique extra Sn^δ+ centers and higher CuO centers with enhanced oxidation effect. Based on density functional theory calculations, the enlarged energy difference between Sn^δ+ /CuO centers and the reactants accelerates the electron transfer and decreases the energy barrier for the key intermediates to gain higher formate selectivity. Furthermore, the hollow structure and abundant micropores of SnCu-CNS are also conducive to the reactant transport and availability of active sites during CO₂ electroreduction. In a conventional H-type cell, SnCu-CNS catalyst exhibits a maximum 95.1% faradaic efficiency for formate production. Switching to a flow cell configuration, SnCu-CNS can further deliver partial current densities exceeding 200 mA cm^-2 and over 90% faradaic efficiencies for the formate, superior to most of the reported Sn-based electrocatalysts. This strategy of electronic modulation and morphology engineering in bimetallic oxides can have wide applications to raise electrocatalytic performance.

Controllable States and Porosity of Cu-Carbon for CO2 Electroreduction to Hydrocarbons

The electrocatalytic carbon dioxide reduction reaction (CO₂ RR) to value-added chemical products is an effective strategy for both greenhouse effect mitigation and high-density energy storage. However, controllable manipulation of the oxidation state and porous structure of Cu-carbon based catalysts to achieve high selectivity and current density for a particular product remains very challenging. Herein, a strategy derived from Cu-based metal-organic frameworks (MOFs) for the synthesis of controllable oxidation states and porous structure of Cu-carbon (Cu-pC, Cu₂ O-pC, and Cu₂ O/Cu-pC) is demonstrated. By regulating oxygen partial pressure during the annealing process, the valence state of the Cu and mesoporous structures of surrounding carbon are changed, leads to the different selectivity of products. Cu₂ O/CuO-pC with the higher oxidation state exhibits FE_C2H4 of 65.12% and a partial current density of -578 mA cm^-2 , while the Cu₂ O-pC shows the FE_CH4 over 55% and a partial current density exceeding -438 mA cm^-2 . Experimental and theoretical studies indicate that porous carbon-coated Cu₂ O structures favor the CH₄ pathway and inhibit the hydrogen evolution reaction. This work provides an effective strategy for exploring the influence of the various valence states of Cu and mesoporous carbon structures on the selectivity of CH₄ and C₂ H₄ products in CO₂ RR.

Modulating p-Orbital of Bismuth Nanosheet by Nickel Doping for Electrocatalytic Carbon Dioxide Reduction Reaction

Electrochemical reduction of CO₂ (CO₂ RR) to value-added chemicals is an effective way to harvest renewable energy and utilize carbon dioxide. However, the electrocatalysts for CO₂ RR suffer from insufficient activity and selectivity due to the limitation of CO₂ activation. In this work, a Ni-doped Bi nanosheet (Ni@Bi-NS) electrocatalyst is synthesized for the electrochemical reduction of CO₂ to HCOOH. Physicochemical characterization methods are extensively used to investigate the composition and structure of the materials. Electrochemical results reveal that for the production of HCOOH, the obtained Ni@Bi-NS exhibits an equivalent current density of 51.12 mA cm^-2 at -1.10 V, which is much higher than the pure Bi-NS (18.00 mA cm^-2 at -1.10 V). A high Faradaic efficiency over 92.0 % for HCOOH is achieved in a wide potential range from -0.80 to -1.10 V, and particularly, the highest efficiency of 98.4 % is achieved at -0.90 V. Both experimental and theoretical results reveal that the superior activity and selectivity are attributed to the doping effect of Ni on the Bi nanosheet. The density functional theory calculation reveals that upon doping, the charge is transferred from Ni to the adjacent Bi atoms, which shifts the p-orbital electronic density states towards the Fermi level. The resultant strong orbital hybridization between Bi and the π* orbitals of CO₂ facilitates the formation of *OCHO intermediates and favors its activation. This work provides an effective strategy to develop active and selective electrocatalysts for CO₂ RR by modulating the electronic density state.

Mechanistic Insights into OC-COH Coupling in CO2 Electroreduction on Fragmented Copper

The carbon-carbon (C-C) bond formation is essential for the electroconversion of CO₂ into high-energy-density C₂₊ products, and the precise coupling pathways remain controversial. Although recent computational investigations have proposed that the OC-COH coupling pathway is more favorable in specific reaction conditions than the well-known CO dimerization pathway, the experimental evidence is still lacking, partly due to the separated catalyst design and mechanistic/spectroscopic exploration. Here, we employ density functional theory calculations to show that on low-coordinated copper sites, the *CO bindings are strengthened, and the adsorbed *CO coupling with their hydrogenation species, *COH, receives precedence over CO dimerization. Experimentally, we construct a fragmented Cu catalyst with abundant low-coordinated sites, exhibiting a 77.8% Faradaic efficiency for C₂₊ products at 300 mA cm^-2. With a suite of in situ spectroscopic studies, we capture an *OCCOH intermediate on the fragmented Cu surfaces, providing direct evidence to support the OC-COH coupling pathway. The mechanistic insights of this research elucidate how to design materials in favor of OC-COH coupling toward efficient C₂₊ production from CO₂ reduction.

Confined Growth of Silver-Copper Janus Nanostructures with {100} Facets for Highly Selective Tandem Electrocatalytic Carbon Dioxide Reduction

Electrocatalytic carbon dioxide reduction reaction (CO₂ RR) holds significant potential to promote carbon neutrality. However, the selectivity toward multicarbon products in CO₂ RR is still too low to meet practical applications. Here the authors report the delicate synthesis of three kinds of Ag-Cu Janus nanostructures with {100} facets (JNS-100) for highly selective tandem electrocatalytic reduction of CO₂ to multicarbon products. By controlling the surfactant and reduction kinetics of Cu precursor, the confined growth of Cu with {100} facets on one of the six equal faces of Ag nanocubes is realized. Compared with Cu nanocubes, Ag₆₅ -Cu₃₅ JNS-100 demonstrates much superior selectivity for both ethylene and multicarbon products in CO₂ RR at less negative potentials. Density functional theory calculations reveal that the compensating electronic structure and carbon monoxide spillover in Ag₆₅ -Cu₃₅ JNS-100 contribute to the enhanced CO₂ RR performance. This study provides an effective strategy to design advanced tandem catalysts toward the extensive application of CO₂ RR.

Tailoring the Surface and Interface Structures of Copper-Based Catalysts for Electrochemical Reduction of CO2 to Ethylene and Ethanol

Electrochemical CO₂ reduction to valuable ethylene and ethanol offers a promising strategy to lower CO₂ emissions while storing renewable electricity. Cu-based catalysts have shown the potential for CO₂ -to-ethylene/ethanol conversion, but still suffer from low activity and selectivity. Herein, the effects of surface and interface structures in Cu-based catalysts for CO₂ -to-ethylene/ethanol production are systematically discussed. Both reactions involve three crucial steps: formation of CO intermediate, CC coupling, and hydrodeoxygenation of C₂ intermediates. For ethylene, the key step is CC coupling, which can be enhanced by tailoring the surface structures of catalyst such as step sites on facets, Cu⁰ /Cu^δ+ species and nanopores, as well as the optimized molecule-catalyst and electrolyte-catalyst interfaces further promoting the higher ethylene production. While the controllable hydrodeoxygenation of C₂ intermediate is important for ethanol, which can be achieved by tuning the stability of oxygenate intermediates through the metallic cluster induced special atomic configuration and bimetallic synergy induced the double active sites on catalyst surface. Additionally, constraining CO coverage by the complex-catalyst interface and stabilizing CO bond by N-doped carbon/Cu interface can also enhance the ethanol selectivity. The structure-performance relationships will provide the guidance for the design of Cu-based catalysts for highly efficient reduction of CO₂ .

Copper Carbonate Hydroxide as Precursor of Interfacial CO in CO2 Electroreduction

Copper electrodes are especially effective in catalysis of C₂ and further multi-carbon products in the CO₂ reduction reaction (CO₂ RR) and therefore of major technological interest. The reasons for the unparalleled Cu performance in CO₂ RR are insufficiently understood. Here, the electrode-electrolyte interface was highlighted as a dynamic physical-chemical system and determinant of catalytic events. Exploiting the intrinsic surface-enhanced Raman effect of previously characterized Cu foam electrodes, operando Raman experiments were used to interrogate structures and molecular interactions at the electrode-electrolyte interface at subcatalytic and catalytic potentials. Formation of a copper carbonate hydroxide (CuCarHyd) was detected, which resembles the mineral malachite. Its carbonate ions could be directly converted to CO at low overpotential. These and further experiments suggested a basic mode of CO₂ /carbonate reduction at Cu electrodes interfaces that contrasted previous mechanistic models: the starting point in carbon reduction was not CO₂ but carbonate ions bound to the metallic Cu electrode in form of CuCarHyd structures. It was hypothesized that Cu oxides residues could enhance CO₂ RR indirectly by supporting formation of CuCarHyd motifs. The presence of CuCarHyd patches at catalytic potentials might result from alkalization in conjunction with local electrical potential gradients, enabling the formation of metastable CuCarHyd motifs over a large range of potentials.

CO2 Electroreduction over Metallic Oxide, Carbon-Based, and Molecular Catalysts: A Mini-Review of the Current Advances

Electrochemical CO2 reduction reaction (CO2RR) is one of the most challenging targets of current energy research. Multi-electron reduction with proton-coupled reactions is more thermodynamically favorable, leading to diverse product distribution. This requires the design of stable electroactive materials having selective product generation and low overpotentials. In this review, we have explored different CO2RR electrocatalysts in the gas phase and H-cell configurations. Five groups of electrocatalysts ranging from metals and metal oxide, single atom, carbon-based, porphyrins, covalent, metal–organic frameworks, and phthalocyanines-based electrocatalysts have been reviewed. Finally, conclusions and prospects have been elaborated.

Accelerating Pd Electrocatalysis for CO2-to-Formate Conversion across a Wide Potential Window by Optimized Incorporation of Cu

Electrochemical reduction of carbon dioxide (CO₂) to formate is a viable way to reduce CO₂ emissions and realize a carbon-neutral energy cycle. Although Pd can convert CO₂ to formate with a high Faradaic efficiency at minimal overpotentials, it suffers from a limited and narrow potential window. Alloying is an important strategy for the catalyst design and tuning the electronic structures. Here, we report a series of PdCu bimetallic alloy catalysts with tunable compositions based on dendritic architectures. Optimal introduction of Cu atoms into the Pd matrix facilitates formate production and suppresses CO generation. In 0.1 M KHCO₃ aqueous solution, our best candidate, Pd₈₂Cu₁₈ catalyst, delivered a high formate Faradaic efficiency of 96.0% at -0.3 V versus RHE. More interestingly, the high selectivity (>90%) toward formate maintained an enlarged electrochemical potential window of 600 mV. The ensemble effect with electronic coupling between Pd and Cu upon alloying and its induced moderate surface O-containing configuration were found to enhance the formate formation and suppress CO poisoning during CO₂ reduction.

Cu3N Nanoparticles with Both (100) and (111) Facets for Enhancing the Selectivity and Activity of CO2 Electroreduction to Ethylene

CO2 electroreduction to high value-added chemicals is a prospective approach to realize the utilization of CO2 resources and mitigate the greenhouse effect. Ethylene (C2H4), as an important chemical materials, is...

Synergistic Effect of Cu2 O Mesh Pattern on High-Facet Cu Surface for Selective CO2 Electroreduction to Ethanol

Although the electroconversion of carbon dioxide (CO₂ ) into ethanol is considered to be one of the most promising ways of using CO₂ , the ethanol selectivity is less than 50% because of difficulties in designing an optimal catalyst that arise from the complicated pathways for the electroreduction of CO₂ to ethanol. Several approaches including the fabrication of oxide-derived structures, atomic surface control, and the Cu⁺ /Cu interfaces have been primarily used to produce ethanol from CO₂ . Here, a combined structure with Cu⁺ and high-facets as electrocatalysts is constructed by creating high-facets of wrinkled Cu surrounded by Cu₂ O mesh patterns. Using chemical vapor deposition graphene growth procedures, the insufficiently grown graphene is used as an oxidation-masking material, and the high-facet wrinkled Cu is simultaneously generated during the graphene growth synthesis. The resulting electrocatalyst shows an ethanol selectivity of 43% at -0.8 V versus reversible hydrogen electrode, which is one of the highest ethanol selectivity values reported thus far. This is attributed to the role of Cu⁺ in enhancing CO binding strength, and the high-facets, which favor C-C coupling and the ethanol pathway. This method for generating the combined structure can be widely applicable not only for electrochemical catalysts but also in various fields.

A gradient Sn4+@Sn2+ core@shell structure induced by a strong metal oxide–support interaction for enhanced CO2 electroreduction

A gradient Sn4+@Sn2+ core@shell structure induced by a strong tin oxide–g-C3N4 support interaction enhanced the adsorption and stabilization of CO2˙−, and hence the CO2RR performances.

Atomically Dispersed Fe-Co Bimetallic Catalysts for the Promoted Electroreduction of Carbon Dioxide

The electroreduction reaction of CO₂ (ECO₂RR) requires high-performance catalysts to convert CO₂ into useful chemicals. Transition metal-based atomically dispersed catalysts are promising for the high selectivity and activity in ECO₂RR. This work presents a series of atomically dispersed Co, Fe bimetallic catalysts by carbonizing the Fe-introduced Co-zeolitic-imidazolate-framework (C-Fe-Co-ZIF) for the syngas generation from ECO₂RR. The synergistic effect of the bimetallic catalyst promotes CO production. Compared to the pure C-Co-ZIF, C-Fe-Co-ZIF facilitates CO production with a CO Faradaic efficiency (FE) boost of 10%, with optimal FE_CO of 51.9%, FE_H2 of 42.4% at - 0.55 V, and CO current density of 8.0 mA cm^-2 at - 0.7 V versus reversible hydrogen electrode (RHE). The H₂/CO ratio is tunable from 0.8 to 4.2 in a wide potential window of - 0.35 to - 0.8 V versus RHE. The total FE_CO+H2 maintains as high as 93% over 10 h. The proper adding amount of Fe could increase the number of active sites and create mild distortions for the nanoscopic environments of Co and Fe, which is essential for the enhancement of the CO production in ECO₂RR. The positive impacts of Cu-Co and Ni-Co bimetallic catalysts demonstrate the versatility and potential application of the bimetallic strategy for ECO₂RR.

The Crystal Plane is not the Key Factor for CO2 -to-Methane Electrosynthesis on Reconstructed Cu2 O Microparticles

Cu₂ O microparticles with controllable crystal planes and relatively high stability have been recognized as a good platform to understand the mechanism of the electrocatalytic CO₂ reduction reaction (CO₂ RR). Herein, we demonstrate that the in situ generated Cu₂ O/Cu interface plays a key role in determining the selectivity of methane formation, rather than the initial crystal plane of the reconstructed Cu₂ O microparticles. Experimental results indicate that the methane evolution is dominated on all three different crystal planes with similar Tafel slopes and long-term stabilities. Density functional theory (DFT) calculations further reveal that *CO is protonated via a similar bridge configuration at the Cu₂ O/Cu interface, regardless of the initial crystal planes of Cu₂ O. The Gibbs free energy changes (ΔG) of *CHO on different reconstructed Cu₂ O planes are close and more negative than that of *OCCOH, indicating the methane formation is more favorable than ethylene on all Cu₂ O crystal planes.