Interfacial Synergy between the Cu Atomic Layer and CeO2 Promotes CO Electrocoupling to Acetate

Nitrate Electroreduction to Ammonia Over Copper-based Catalysts

The electrocatalytic reduction of nitrate (NO3 -) to ammonia (NH3) holds substantial promise, as it transforms NO3 - from polluted water into valuable NH3. However, the reaction is limited by sluggish kinetics and low NH3 selectivity. Cu-based catalysts with unique electronic structures demonstrate rapid NO3 - to NO2 - rate-determining step (RDS) and fast electrocatalytic nitrate reduction reaction (eNO3RR) kinetics among non-noble metal catalysts. Nonetheless, achieving high robustness and selectivity for NH3 with Cu-based catalysts remains a significant challenge. This review provides a comprehensive overview of the reaction mechanisms in eNO3RR, highlights how the structures of monometallic and bimetallic Cu-based catalyst affect catalytic properties, and discusses the current challenges as well as prospects in eNO3RR.

In situ construction of a built-in electric field for efficient CO2 electroreduction

Studying the structural evolution process of Cu-based heterogeneous catalysts is of great significance for converting CO2 into valuable chemicals. In this study, we suggest an efficient synthesis method for Cu-based catalysts that facilitate the formation of heterojunctions with In2O3, providing a mild and effective route for CO2 and H2O reduction. The resulting syngas ratios (CO/H2) are maintained within a narrow range of 0.6 to 1.5 across a broad potential window. Experiments and theoretical calculations demonstrate that the in situ reconstructed internal electric field significantly lowers the energy barrier for CO2 reduction, favoring the formation of *CO intermediates while concurrently suppressing the hydrogen evolution reaction (HER) during the electrochemical CO2 reduction process.

Electron effect regulation: A study on the influence of electron-donating and withdrawing group modification on the performance of metal-coordinated catalysts for electrochemical carbon dioxide reduction

Electron effect regulation is a crucial factor influencing the activity and selectivity of Cu-based coordination compound catalysts in the electrochemical carbon dioxide reduction reaction (CO2RR). Despite significant progress, the structure-activity relationship and the underlying regulatory mechanisms warrant further in-depth investigation. In this study, three types of Cu-[ONNO] tetradentate coordination molecular catalysts with varying electron densities, namely Cu-N2O2, methoxy-modified Cu-N2O2 (Cu-EDG-N2O2), and nitro-modified Cu-N2O2 (Cu-EWG-N2O2), were prepared using a substituent regulation strategy. The prepared catalyst's micromorphology and structural characteristics were analyzed using various characterization methods. Systematic electrocatalytic CO2RR experiments were conducted to evaluate the performance of these catalysts. Compared to the unmodified Cu-N2O2, the Cu-EDG-N2O2 catalyst exhibited superior reduction performance for CH4 and C2H4 products. At an applied potential of -1.7 V vs. the reversible hydrogen electrode, the Faradaic efficiencies for CH4 and C2H4 of Cu-EDG-N2O2 were 37.8 ± 2.2 % and 25.0 ± 0.5 %, respectively. In contrast, the Cu-EWG-N2O2 catalyst demonstrated higher activity towards the production of H2 as a by-product. The effects of electronic properties of substitutions on catalyst performance were revealed by combining experimental characterization and theoretical simulation. The results showed that the conjugation effect of the -OCH3 group facilitates faster electron transfer between Cu and CO2, thereby enhancing CO2RR activity. Additionally, the introduction of different substituents modulates the local microenvironment around the Cu active centers, significantly influencing the catalytic performance. This study provides valuable theoretical and experimental insights into the design of efficient Cu-N2O2-type metal coordination electrocatalysts for CO2RR processes.

Atomically dispersed cerium on copper tailors interfacial water structure for efficient CO-to-acetate electroreduction

Electrosynthesis of acetate from carbon monoxide (CO) powered by renewable electricity offers one promising avenue to obtain valuable carbon-based products but undergoes unsatisfied selectivity because of the competing hydrogen evolution reaction. We report here a cerium single atoms (Ce-SAs) modified crystalline-amorphous dual-phase copper (Cu) catalyst, in which Ce SAs reduce the electron density of the dual-phase Cu, lowering the proportion of interfacial K+ ion hydrated water (K·H2O) and thereby decreasing the H* coverage on the catalyst surface. Meanwhile, the electron transfer from dual-phase Cu to Ce SAs yields Cu+ species, which boost the formation of active atop-adsorbed *CO (COatop), improving COatop-COatop coupling kinetics. These together lead to the preferential pathway of ketene intermediate (*CH2-C=O) formation, which then reacts with OH- enriched by pulsed electrolysis to generate acetate. Using this catalyst, we achieve a high Faradaic efficiency of 71.3 ± 2.1% toward acetate and a time-averaged acetate current density of 110.6 ± 2.0 mA cm-2 under a pulsed electrolysis mode. Furthermore, a flow-cell reactor assembled by this catalyst can produce acetate steadily for at least 138 hours with selectivity greater than 60%.

Zeolite-confined Cu single-atom clusters stably catalyse CO to acetate at 1 A cm-2 beyond 1,000 h

The electrochemical CO reduction reaction (CORR) has attracted a surge of research interest in sustainably producing high-value multi-carbon products, such as acetate. Nevertheless, most current CORR catalysts exhibit low acetate current densities, poor longevity and limited acetate selectivity. Here we present a Zeolite Socony Mobil-confined Cu single-atom cluster (CuZSM SACL) for CORR, in which Cu SAs are chemically anchored via robust Cu-O-Si bonds while Cu CLs are physically trapped within the porous framework of zeolite cavities. Consequently, the CuZSM SACL-containing membrane electrode assembly enables a remarkable CO-to-acetate current density of 1.8 A cm-2 with a high acetate Faraday efficiency of 71 ± 3%. More importantly, we demonstrate that the Cu-based membrane electrode assembly can stably catalyse CO to acetate at an industrial current density of 1 A cm-2 at 2.7 V (Faraday efficiency 61 ± 5%) beyond 1,000 h at atmospheric pressure. This milestone sheds light on high-performing Cu-type catalysts for practical CORR applications.

Interfacial Oxygen Vacancy of CuOx-CeO2 Enhances H2O2 Activation and Pollutant Degradation

In the Fenton process, the development of catalysts with a wide pH range and good stability has been a long-term goal for water treatment purpose. This study proposes a strategy to solve this problem by preparing supported catalysts CuOx@CeO2-IE using an ion exchange reversed loading method. The generation of a large number of interfacial oxygen vacancies with Cu-OV-Ce (OV represents an oxygen vacancy site) structures prolongs the O-O bond of H2O2, promotes the rupture of the peroxide bond of H2O2, and thereby promotes the activation of H2O2 on the surface of the catalyst. The results show that with a H2O2 concentration of 5 mM and CuOx@CeO2-IE at 50 mg/L, the removal rate of bisphenol A is 94.1 % in 60 min, in which • OH dominates the degradation process. Moreover, the system can operate well within a relatively wide pH range (4-8). This study provides a novel strategy for the design of Fenton catalysts with a wide pH suitability and excellent stability.

Metal-organic framework-derived silver/copper-oxide catalyst for boosting the productivity of carbon dioxide electrocatalysis to ethylene

Electrochemical reduction of CO2 into valuable multi-carbon (C2) chemicals holds promise for mitigating CO2 emissions and enabling artificial carbon cycling. However, achieving high selectivity remains challenging due to the limited activity and active sites of CC coupling catalysts. Herein, we report an Ag-modified Cu-oxide catalyst (CuO/Ag@C) derived from metal-organic frameworks (MOF), capable of efficiently converting CO2 to C2H4. The MOF-derived porous carbon confines the size of metal nanoparticles, ensuring sufficient exposure of active sites. Remarkably, the CuO/Ag@C catalyst achieves an impressive Faradaic efficiency of 48.6% for C2H4 at -0.7 V vs. RHE, demonstrating excellent stability. Both experimental results and theoretical calculations indicate that Ag sites promote the production of CO, enhancing the coverage of *CO on Cu sites. Furthermore, the reconfiguration of charge density at the Cu-Ag interface optimizes the electronic states of the reaction sites, reducing the formation energy of the key intermediate *OCCHO, thereby favoring C2H4 production effectively. This work provides insight into structurally rational catalyst design for highly active and selective multiphase catalysts.

Improving the Stability of Gas Diffusion Electrodes for CO2 Electroreduction to Formate with Sn and In-Based Catalysts at 500 mA cm-2: Effect of Electrode Design and Operation Mode

The electrochemical carbon dioxide reduction reaction (CO2RR) using renewable electricity sources could provide a sustainable solution for generating valuable chemicals, such as formate salt or formic acid. However, an efficient, stable, and scalable electrode generating formate at industrially viable current densities (>100 mA cm-2) is yet to be developed. Sn or In-based catalysts in gas diffusion electrodes (GDE) can efficiently produce formate. However, their long-term durability is limited owing to catalyst deactivation, carbonate deposition, and electrode flooding. Herein, a systematic study of 20 cm2 GDEs with SnO2 and In2O3 catalyst layers is presented in conjunction with various electrode operation strategies (i.e., flow-by vs flow through, dry vs humidified CO2, continuous vs reverse polarity pulse electrolysis). It is demonstrated that the incorporation of CeO2 nanoparticles as a promoter in either SnO2 or In2O3 catalyst layers coupled with intermittent reverse polarity pulse operation dramatically improves the GDE stability during 12 h of tests at 500 mA cm-2 with over 90% formate Faradaic efficiency. Due to its strong oxidizing capacity, CeO2 helps Sn and In regain their valence state of + IV and + III, respectively, which are in situ reduced during CO2RR, as shown by the surface characterization of the electrodes. The effect of the initial particle size of SnO2 and reverse polarity pulse on the catalytic activity, durability, and carbonate salt precipitation in the GDE have also been addressed. Regarding two-phase flow dynamics, the quasi-convective gas flow through the GDE was more beneficial than the gas flow-by mode for enabling stable operation at high current densities (up to 500 mA cm-2). The synergistic approach of catalyst layer engineering coupled with diverse GDE operation modes explored here is promising for the scale-up of efficient and durable reactors for the CO2RR to formate and CO2 redox flow batteries.

Establishing Non-Stoichiometric Ti4O7 Assisted Asymmetrical C-C Coupling for Highly Energy-Efficient Electroreduction of Carbon Monoxide

Exploring an appropriate support material for Cu-based electrocatalyst is conducive for stably producing multi-carbon chemicals from electroreduction of carbon monoxide. However, the insufficient metal-support adaptability and low conductivity of the support would hinder the C-C coupling capacity and energy efficiency. Herein, non-stoichiometric Ti4O7 was incorporated into Cu electrocatalysts (Cu-Ti4O7), and served as a highly conductive and stable support for highly energy-efficient electrochemical conversion of CO. The abundant oxygen vacancies originated from ordered lattice defects in Ti4O7 facilitate the water dissociation and the CO adsorption to accelerate the hydrogenation to *COH. The highly adaptable metal-support interface of Cu-Ti4O7 enables a direct asymmetrical C-C coupling between *CO on Cu and *COH on Ti4O7, which significantly lowers the reaction energy barrier for C2+ products formation. Additionally, the excellent electroconductivity of Ti4O7 benefits the reaction charge transfer through robust Cu/Ti4O7 interface for minimizing the energy loss. Thus, the optimized 20Cu-Ti4O7 catalyst exhibits an impressive selectivity of 96.4 % and ultrahigh energy efficiency of 45.1 % for multi-carbon products, along with a remarkable partial current density of 432.6 mA cm-2. Our study underscores a novel C-C coupling strategy between Cu and the support material, advancing the development of Cu-supported catalysts for highly efficient electroreduction of carbon monoxide.

Boric acid functionalized Fe3O4@CeO2/Tb-MOF as a luminescent nanozyme for fluorescence detection and degradation of caffeic acid

Caffeic acid (CA) is a natural polyphenol that can have various positive effects on human health. However, its extraction and processing can cause significant ecological issues. Therefore, it is crucial to detect and degrade CA effectively in the environment. In this study, we have developed a multifunctional magnetic luminescent nanozyme, Fe3O4@CeO2/Tb-MOF, which combines peroxidase activity to detect and degrade CA. The fluorescence of the nanozyme was significantly attenuated due to the specific nucleophilic reaction between its boronic acid moiety and the o-diphenol hydroxyl group of CA, energy competition absorption and photo-induced electron transfer (PET) effect. This nanozyme demonstrates a linear detection range from 50 nM to 500 μM and an exceptionally low detection limit of 18.9 nM, along with remarkable selectivity and stability. Moreover, the synergistic catalysis of Fe3O4 and CeO2 within Fe3O4@CeO2/Tb-MOF fosters peroxidase activity, leading to the generation of substantial free radicals catalyzed by H2O2, which ensures the efficient degradation of CA (∼95%). The superparamagnetic property of Fe3O4 further enables the efficient reuse and recycling of the nanozyme. This research provides a novel approach for the concurrent detection and remediation of environmental contaminants.

Interfacial Accumulation and Stability Enhancement Effects Triggered by Built-in Electric Field of SnO2/LaOCl Nanofibers Boost Carbon Dioxide Electroreduction

Constructing a built-in interfacial electric field (BIEF) is an effective approach to enhance the electrocatalysts performance, but it has been rarely demonstrated for electrochemical carbon dioxide reduction reaction (CO2RR) to date. Herein, for the first time, SnO2/LaOCl nanofibers (NFs) with BIEF is created by electrospinning, exhibiting a high Faradaic efficiency (FE) of 100% C1 product (CO and HCOOH) at -0.9--1.1 V versus reversible hydrogen electrode (RHE) and a maximum FEHCOOH of 90.1% at -1.2 VRHE in H-cell, superior to the commercial SnO2 nanoparticles (NPs) and LaOCl NFs. SnO2/LaOCl NFs also exhibit outstanding stability, maintaining negligible activity degradation even after 10 h of electrolysis. Moreover, their current density and FEHCOOH are almost 400 mA cm-2 at -2.31 V and 83.4% in flow-cell. The satisfactory CO2RR performance of SnO2/LaOCl NFs with BIEF can be ascribed to tight interface of coupling SnO2 NPs and LaOCl NFs, which can induce charge redistribution, rich active sites, enhanced CO2 adsorption, as well as optimized Gibbs free energy of *OCHO. The work reveals that the BIEF will trigger interfacial accumulation and stability enhancement effects in promoting CO2RR activity and stability of SnO2-based materials, providing a novel approach to develop stable and efficient CO2RR electrocatalysts.

Inverted loading strategy regulates the Mn-OV-Ce sites for efficient fenton-like catalysis

Regulating interfacial active sites to improve peroxymonosulfate (PMS) activation efficiency is a hot topic in the heterogeneous catalysis field. In this study, we develop an inverted loading strategy to engineer asymmetric Mn-OV-Ce sites for PMS activation. Mn3O4@CeO2 prepared by loading CeO2 nanoparticles onto Mn3O4 nanorods exhibits the highest catalytic activity and stability, which is due to the formation of more oxygen vacancies (OV) at the Mn-OV-Ce sites, and the surface CeO2 layer effectively inhibits corrosion by preventing the loss of manganese ion active species into the solution. In situ characterizations and density functional theory (DFT) studies have revealed effective bimetallic redox cycles at asymmetric Mn-OV-Ce active sites, which promote surface charge transfer, enhance the adsorption reaction activity of active species toward pollutants, and favor PMS activation to generate (•OH, SO4•-, O2•- and 1O2) active species. This study provides a brand-new perspective for engineering the interfacial behavior of PMS activation.

Highly Selective Electrocatalytic CO2 Conversion to Tailored Products through Precise Regulation of Hydrogenation and C-C Coupling

The electrochemical reduction reaction of carbon dioxide (CO2RR) into valuable products offers notable economic benefits and contributes to environmental sustainability. However, precisely controlling the reaction pathways and selectively converting key intermediates pose considerable challenges. In this study, our theoretical calculations reveal that the active sites with different states of copper atoms (1-3-5-7-9) play a pivotal role in the adsorption behavior of the *CHO critical intermediate. This behavior dictates the subsequent hydrogenation and coupling steps, ultimately influencing the formation of the desired products. Consequently, we designed two model electrocatalysts comprising Cu single atoms and particles supported on CeO2. This design enables controlled *CHO intermediate transformation through either hydrogenation with *H or coupling with *CO, leading to a highly selective CO2RR. Notably, our selective control strategy tunes the Faradaic efficiency from 61.1% for ethylene (C2H4) to 61.2% for methane (CH4). Additionally, the catalyst demonstrated a high current density and remarkable stability, exceeding 500 h of operation. This work not only provides efficient catalysts for selective CO2RR but also offers valuable insights into tailoring surface chemistry and designing catalysts for precise control over catalytic processes to achieve targeted product generation in CO2RR technology.

Engineering highly selective CO2 electroreduction in Cu-based perovskites through A-site cation manipulation

Perovskites exhibit considerable potential as catalysts for various applications, yet their performance modulation in the carbon dioxide reduction reaction (CO2RR) remains underexplored. In this study, we report a strategy to enhance the electrocatalytic carbon dioxide (CO2) reduction activity via Ce-doped La2CuO4 (LCCO) and Sr-doped La2CuO4 (LSCO) perovskite oxides. Specifically, compared to pure phase La2CuO4 (LCO), the Faraday efficiency (FE) for CH4 of LCCO at -1.4 V vs. RHE (reversible hydrogen electrode) is improved from 38.9% to 59.4%, and the FECO2RR of LSCO increased from 68.8% to 85.4%. In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy spectra results indicate that the doping of A-site ions promotes the formation of *CHO and *HCOO, which are key intermediates in the production of CH4, compared to the pristine La2CuO4. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and double-layer capacitance (Cdl) outcomes reveal that heteroatom-doped perovskites exhibit more oxygen vacancies and higher electrochemical active surface areas, leading to a significant improvement in the CO2RR performance of the catalysts. This study systematically investigates the effect of A-site ion doping on the catalytic activity center Cu and proposes a strategy to improve the catalytic performance of perovskite oxides.

Low-coordinated copper facilitates the *CH2CO affinity at enhanced rectifying interface of Cu/Cu2O for efficient CO2-to-multicarbon alcohols conversion

The carbon-carbon coupling at the Cu/Cu2O Schottky interface has been widely recognized as a promising approach for electrocatalytic CO2 conversion into value-added alcohols. However, the limited selectivity of C2+ alcohols persists due to the insufficient control over rectifying interface characteristics required for precise bonding of oxyhydrocarbons. Herein, we present an investigation into the manipulation of the coordination environment of Cu sites through an in-situ electrochemical reconstruction strategy, which indicates that the construction of low-coordinated Cu sites at the Cu/Cu2O interface facilitates the enhanced rectifying interfaces, and induces asymmetric electronic perturbation and faster electron exchange, thereby boosting C-C coupling and bonding oxyhydrocarbons towards the nucleophilic reaction process of *H2CCO-CO. Impressively, the low-coordinated Cu sites at the Cu/Cu2O interface exhibit superior faradic efficiency of 64.15  ±  1.92% and energy efficiency of ~39.32% for C2+ alcohols production, while maintaining stability for over 50 h (faradic efficiency >50%, total current density = 200 mA cm-2) in a flow-cell electrolyzer. Theoretical calculations, operando synchrotron radiation Fourier transform infrared spectroscopy, and Raman experiments decipher that the low-coordinated Cu sites at the Cu/Cu2O interface can enhance the coverage of *CO and adsorption of *CH2CO and CH2CHO, facilitating the formation of C2+ alcohols.

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.

Modulating band structure through introducing Cu0/CuxO composites for the improved visible light driven ammonia synthesis

The photocatalytic performance of ceria-based materials can be tuned by adjusting the surface structures with decorating the transition-metal, which are considered as the important active sites. Herein, cuprous oxide-metallic copper composite-doped ceria nanorods were assembled through a simple hydrothermal reduction method. The photocatalytic ammonia synthesis rates exhibit an inverted "V-shaped" trend with increasing Cu0/CuxO mole ratio. The best ammonia production rate, approximately 900 or 521 µmol·gcal-1·h-1 under full-spectra or visible light, can be achieved when the Cu0/CuxO ratio is approximately 0.16, and this value is 8 times greater than that of the original sample. The absorption edge of the as-prepared samples shifted towards visible wavelengths, and they also had appropriate ammonia synthesis levels. This research provides a strategy for designing noble metal-free photocatalysts through introducing the metal/metallic oxide compositesto the catalysts.

Tuning the Catalytic Selectivity Toward C2+ Oxygenate Products by Manipulating Cu Oxidation States in CO Electroreduction

Enhancing the reaction selectivity for multicarbon products (C2+) is an important goal for the electrochemical CO(2) reduction (ECO(2)R) process. Cuprous compounds have demonstrated promising C2+ selectivity in the ECO(2)R process, but further investigation is necessary to thoroughly elucidate their catalytic behavior toward C2+ oxygenate production. In this study, copper nitride-based materials with varying reduction rates were employed as precatalysts. Consequently, a relationship between the selectivity toward C2+ oxygenates and the Cu oxidation state during the ECOR process is established. Results of theoretical and experimental analyses reveal that the Cu0/Cu+ interface plays a key role in enhancing *CO adsorption while lowering the formation energy of *CH2CO, thereby promoting acetate production. This work highlights the significance of the Cu0/Cu+ interface in the regulation of C2+ oxygenate production and paves the way for the development of highly selective catalysts in the future.

Rare earth oxide based electrocatalysts: synthesis, properties and applications

As an important strategic resource, rare earths (REs) constitute 17 elements in the periodic table, namely 15 lanthanides (Ln) (La-Lu, atomic numbers from 57 to 71), scandium (Sc, atomic number 21) and yttrium (Y, atomic number 39). In the field of catalysis, the localization and incomplete filling of 4f electrons endow REs with unique physical and chemical properties, including rich electronic energy level structures, variable coordination numbers, etc., making them have great potential in electrocatalysis. Among various RE catalytic materials, rare earth oxide (REO)-based electrocatalysts exhibit excellent performances in electrocatalytic reactions due to their simple preparation process and strong structural variability. At the same time, the electronic orbital structure of REs exhibits excellent electron transfer ability, which can reduce the band gap and energy barrier values of rate-determining steps, further accelerating the electron transfer in the electrocatalytic reaction process; however, there is a lack of systematic review of recent advances in REO-based electrocatalysis. This review systematically summarizes the synthesis, properties and applications of REO-based nanocatalysts and discusses their applications in electrocatalysis in detail. It includes the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), methanol oxidation reaction (MOR), nitrogen reduction reaction (NRR) and other electrocatalytic reactions and further discusses the catalytic mechanism of REs in the above reactions. This review provides a timely and comprehensive summary of the current progress in the application of RE-based nanomaterials in electrocatalytic reactions and provides reasonable prospects for future electrocatalytic applications of REO-based materials.

Continuously Producing Highly Concentrated and Pure Acetic Acid Aqueous Solution via Direct Electroreduction of CO2

It is crucial to achieve continuous production of highly concentrated and pure C2 chemicals through the electrochemical CO2 reduction reaction (eCO2RR) for artificial carbon cycling, yet it has remained unattainable until now. Despite one-pot tandem catalysis (dividing the eCO2RR to C2 into two catalytical reactions of CO2 to CO and CO to C2) offering the potential for significantly enhancing reaction efficiency, its mechanism remains unclear and its performance is unsatisfactory. Herein, we selected different CO2-to-CO catalysts and CO-to-acetate catalysts to construct several tandem catalytic systems for the eCO2RR to acetic acid. Among them, a tandem catalytic system comprising a covalent organic framework (PcNi-DMTP) and a metal-organic framework (MAF-2) as CO2-to-CO and CO-to-acetate catalysts, respectively, exhibited a faradaic efficiency of 51.2% with a current density of 410 mA cm-2 and an ultrahigh acetate yield rate of 2.72 mmol m-2 s-1 under neutral conditions. After electrolysis for 200 h, 1 cm-2 working electrode can continuously produce 20 mM acetic acid aqueous solution with a relative purity of 95+%. Comprehensive studies revealed that the performance of tandem catalysts is influenced not only by the CO supply-demand relationship and electron competition between the two catalytic processes in the one-pot tandem system but also by the performance of the CO-to-C2 catalyst under diluted CO conditions.

Directing the Selectivity of CO Electrolysis to Acetate by Constructing Metal-Organic Interfaces

Electrochemically converting CO2 to valuable chemicals holds great promise for closing the anthropogenic carbon cycle. Owing to complex reaction pathways and shared rate-determining steps, directing the selectivity of CO2 /CO electrolysis to a specific multicarbon product is very challenging. We report here a strategy for highly selective production of acetate from CO electrolysis by constructing metal-organic interfaces. We demonstrate that the Cu-organic interfaces constructed by in situ reconstruction of Cu complexes show very impressive acetate selectivity, with a high Faradaic efficiency of 84.2 % and a carbon selectivity of 92.1 % for acetate production, in an alkaline membrane electrode assembly electrolyzer. The maximum acetate partial current density and acetate yield reach as high as 605 mA cm-2 and 63.4 %, respectively. Thorough structural characterizations, control experiments, operando Raman spectroscopy measurements, and density functional theory calculation results indicate that the Cu-organic interface creates a favorable reaction microenvironment that enhances *CO adsorption, lowers the energy barrier for C-C coupling, and facilitates the formation of CH3 COOH over other multicarbon products, thus rationalizing the selective acetate production.

Modulating Electronic Structures of Iron Clusters through Orbital Rehybridization by Adjacent Single Copper Sites for Efficient Oxygen Reduction

The atom-cluster interaction has recently been exploited as an effective way to increase the performance of metal-nitrogen-carbon catalysts for oxygen reduction reaction (ORR). However, the rational design of such catalysts and understanding their structure-property correlations remain a great challenge. Herein, we demonstrate that the introduction of adjacent metal (M)-N4 single atoms (SAs) could significantly improve the ORR performance of a well-screened Fe atomic cluster (AC) catalyst by combining density functional theory (DFT) calculations and experimental analysis. The DFT studies suggest that the Cu-N4 SAs act as a modulator to assist the O2 adsorption and cleavage of O-O bond on the Fe AC active center, as well as optimize the release of OH* intermediates to accelerate the whole ORR kinetic. The depositing of Fe AC with Cu-N4 SAs on nitrogen doped mesoporous carbon nanosheet are then constructed through a universal interfacial monomicelles assembly strategy. Consistent with theoretical predictions, the resultant catalyst exhibits an outstanding ORR performance with a half-wave potential of 0.92 eV in alkali and 0.80 eV in acid, as well as a high power density of 214.8 mW cm-2 in zinc air battery. This work provides a novel strategy for precisely tuning the atomically dispersed poly-metallic centers for electrocatalysis.