N-doped Cu2O with the tunable Cu0 and Cu+ sites for selective CO2 electrochemical reduction to ethylene.

The electrochemical carbon dioxide reduction reaction (CO2RR) to high value-added fuels or chemicals driven by the renewable energy is promising to alleviate global warming. However, the selective CO2 reduction to C2 products remains challenge. Cu-based catalyst with the specific Cu0 and Cu+ sites is important to generate C2 products. This work used nitrogen (N) to tune amounts of Cu0 and Cu+ sites in Cu2O catalysts and improve C2-product conversion. The controllable Cu0/Cu+ ratio of Cu2O catalyst from 0.16 to 15.19 was achieved by adjusting the N doping amount using NH3/Ar plasma treatment. The major theme of this work was clarifying a volcano curve of the ethylene Faraday efficiency as a function of the Cu0/Cu+ ratio. The optimal Cu0/Cu+ ratio was determined as 0.43 for selective electroreduction CO2 to ethylene. X-ray spectroscopy and density functional theory (DFT) calculations were employed to elucidate that the strong interaction between N and Cu increased the binding energy of NCu bond and stabilize Cu+, resulting in a 92.3% reduction in the potential energy change for *CO-*CO dimerization. This study is inspiring in designing high performance electrocatalysts for CO2 conversion.

Dynamic Adaptation of Active Site Driven by Dual-side Adsorption in Single-Atomic Catalysts During CO2 Electroreduction.

Single-atom iron embedded in N-doped carbon (Fe-N-C) is among the most representative single-atomic catalysts (SACs) for electrochemical CO2 reduction reaction (CO2RR). Despite the simplicity of the active site, the CO2-to-CO mechanism on Fe-N-C remains controversial. Firstly, there is a long debate regarding the rate-determining step (RDS) of the reactions. Secondly, recent computational and experimental studies are puzzled by the fact that the CO-poisoned Fe centers still remain highly active at high potentials. Thirdly, there are ongoing challenges in elucidating the high selectivity of hydrogen evolution reaction (HER) over CO2RR at high potentials. In this work, we introduce a novel CO2RR mechanism on Fe-N-C, which was inspired by the dynamic of active sites in biological systems. By employing grand-canonical density functional theory and kinetic Monte-Carlo, we found that the RDS is not fixed but changes with the applied potential. We demonstrated that our proposed dual-side mechanisms could clarify the reason behind the high catalytic activity of CO-poisoned metal centers, as well as the high selectivity of HER over CO2RR at high potential. This study provides a fundamental explanation for long-standing puzzles of an important catalyst and calls for the importance of considering the dynamic of active sites in reaction mechanisms.

Delocalization State-Stabilized Znδ+ Active Sites for Highly Selective and Durable CO2 Electroreduction.

Zinc (Zn)-based materials are cost-effective and promising single-metal catalysts for CO2 electroreduction to CO but is still challenged by low selectivity and long-term stability. Undercoordinated Zn (Znδ+) sites have been demonstrated to be powerful active centers with appropriate *COOH affinity for efficient CO production However, electrochemical reduction conditions generally cause the inevitable reduction of Znδ+, resulting in the decline of CO efficiency over prolonged operation. Herein, a Zn cyanamide (ZnNCN) catalyst is constructed for highly selective and durable CO2 electroreduction, wherein the delocalized Zn d-electrons and resonant structure of cyanamide ligand prevent the self-reduction of ZnNCN and maintain Znδ+ sites under cathodic conditions. The mechanism studies based on density functional theory and operando spectroscopies indicate that delocalized Znδ+ site can stabilize the key *COOH intermediate through hard-soft acid-base theory, therefore thermodynamically promoting CO2-to-CO conversion. Consequently, ZnNCN delivers a CO Faradaic efficiency (FE) of up to 93.9% and further exhibits a remarkable stability lifespan of 96 h, representing a significant advancement in developing robust Zn-based electrocatalysts. Beyond expanding the variety of CO2 reduction catalysts, this work also offers insights into understanding the structure-function sensitivity and controlling dynamic active sites.

Boron-Doping Engineering in AgCd Bimetallic Catalyst Enabling Efficient CO2 Electroreduction to CO and Aqueous Zn-CO2 Batteries.

The limited adsorption and activation of CO2 on catalyst and the high energy barrier for intermediate formation hinder the development of electrochemical CO2 reduction reactions (CO2RR). Herein, this work reports a boron (B) doping engineering in AgCd bimetals to alleviate the above limitations for efficient CO2 electroreduction to CO and aqueous Zn-CO2 batteries. Specifically, the B-doped AgCd bimetallic catalyst (AgCd-B) is prepared via a simple reduction reaction at room temperature. A combination of in situ experiments and density functional theory (DFT) calculations demonstrates that B-doping simultaneously enhances the adsorption and activation of CO2 and reduces the binding energy of the intermediates by moderating the electronic structure of bimetals. As a result, the AgCd-B catalyst exhibits a high CO Faraday efficiency (FECO) of 99% at -0.8 V versus reversible hydrogen electrode (RHE). Additionally, it maintains a FECO over 92% at a wide potential window of 600 mV (-0.6 to -1.1 V versus RHE). Furthermore, the AgCd-B catalyst coupled with the Zn anode to assemble aqueous Zn-CO2 batteries shows a power density of 20.18 mW cm-2 and a recharge time of 33 h.

Establishing a Robust Nonlinear Targeted Switch for C1 Electroproduction in Atomic Alloy Cox/Pd Bimetallenes.

Establishing a targeted switch for CO2 conversion under electric drive is essential for achieving carbon-balance by enabling selective chemicals. However, engineering the topological assembly of active sites to precisely regulate the competing pathways for various intermediates has been plagued by unclear structure-function relationships. To tailor the CO/formate pathways, herein we established a robust nonlinear targeted switch with tunable active Cox sites integrated into Pd metallene, which involves Co1/Pd single-atom alloy (favoring CO) and Co2/Pd diatomic alloy (favoring formate). Transitioning from Co1/Pd to Co2/Pd atomic alloy bimetallenes resulted in a nonlinear, high-contrast flip in selectivity, surpassing 94% for CO and formate productions in both H-cell and flow cell. Furthermore, the superior selectivity and current efficiency for CO (> 80 %) and formate (> 88%) were consistently maintained at -150 mA cm-2 over continuous 200 h. Theoretical simulations and in-situ spectroscopy analyses unveiled that appropriate adjacent metal site combinations (Pd-Pd, Pd-Co and Co-Co) lead to tunable dz2 band center and a nonlinear shift in preferred adsorption configurations of intermediates, dictating the C1 pathways. Our finding reveals a desired switch in C1 selectivity and robust stability within Cox/Pd system, providing a new perspective for fine-tuning energy conversion processes through specific topological assembly.

Prompting CO2 Electroreduction to Ethanolby Iron Group Metal Ion Dopants Induced Multi-sites at the Interface of SnSe/SnSe2 p-n Heterojunction.

The development of non-copper-based materials for CO2 electroreduction to ethanol with high selectivity at large current density is highly desirable, but still a great challenge. Herein, we report iron group metal ions of M2+ (M = Fe, Co, or Ni)-doped amorphous/crystalline SnSe/SnSe2nanorod/nanosheet hierarchical structures (a/c-SnSe/SnSe2) for selective CO2 electroreduction to ethanol. Iron group metal ions doping induces multiple active sites at the interface of M2+-doped SnSe/SnSe2 p-n heterojunction, which strengthens *CO intermediate binding for further C-C coupling to eventual ethanol generation. As a representative, Fe9.0%-a/c-SnSe/SnSe2 exhibits an ethanol Faradaic efficiency of 62.7% and a partial current density of 239.0 mA cm-2 at -0.6 V in a flow cell. Moreover, it can output an ethanol Faradaic efficiency of 63.5% and a partial current density of 201.2 mA cm-2 with a full-cell energy efficiency of 24.1% at 3.0 V in a membrane electrode assembly (MEA) electrolyzer. This work provides insight into non-Cu based catalyst design for stabilizing the key intermediates for selective ethanol production from CO2 electroreduction.

Carbon Nanocage Supported Asymmetrically Coordinated Nickle Single-Atom for Enhanced CO2 Electroreduction in Membrane Electrode Assembly.

Designing efficient catalysts for operating CO2 electroreduction in membrane electrode assembly (MEA) faces significant obstacles. Herein, we propose an asymmetrically coordinated Ni SAC featuring axial Br coordination at NiN4Br sites anchoring onto hollow Br/N co-doped carbon nanocages, achieved through a NaBr-assisted confined-pyrolysis strategy. The Ni-NBr-C exhibits a high CO Faradaic efficiency (FECO> 97%) over the current density range of 50 to 350 mA cm-2 in the MEA device. Furthermore, Ni-NBr-C shows a stable cell voltage of 2.66 ± 0.2 V while delivering a large current density of 350 mA cm-2 over an 85-hour long-term operation, demonstrating its potential for industrial-scale applications. Advanced characterization techniques and theoretical calculations reveal that the coordination and doping of Br enhance the intrinsic activity but also highlighted that the unique pore structure improves mass transfer efficiency.

Engineering a Cu-Pd Paddle-Wheel Metal-Organic Framework for Selective CO 2 Electroreduction.

Optimizing the binding energy between the intermediate and the active site is a key factor for tuning catalytic product selectivity and activity in the electrochemical carbon dioxide reduction reaction. Copper active sites are known to reduce CO2 to hydrocarbons and oxygenates, but suffer from poor product selectivity due to the moderate binding energies of several of the reaction intermediates. Here, we report an ion exchange strategy to construct Cu-Pd paddle wheel dimers within Cu-based metal-organic frameworks (MOFs), [Cu3-xPdx(BTC)2] (BTC = benzentricarboxylate), without altering the overall MOF structural properties. Compared to the pristine Cu MOF ([Cu3(BTC)2], HKUST-1), the Cu-Pd MOF shifts CO2 electroreduction products from diverse chemical species to selective CO generation. In situ X-ray absorption fine structure analysis of the catalyst oxidation state and local geometry, combined with theoretical calculations, reveal that the incorporation of Pd within the Cu-Pd paddle wheel node structure of the MOF promotes adsorption of the key intermediate COOH* at the Cu site. This permits CO-selective catalytic mechanisms and thus advances our understanding of the interplay between structure and activity toward electrochemical CO2 reduction using molecular catalysts.

Controllable Regulation of CO2 Adsorption Behavior via Precise Charge Donation Modulation for Highly Selective CO2 Electroreduction to Formic Acid.

The synthesis of value-added products via CO2 electroreduction (CO2ER) is of great significance, but the development of efficient and versatile strategies for the controllable selectivity tuning is extremely challenging. Herein, the tuning of CO2ER selectivity through the modulation of CO2 adsorption behavior is proposed. Using the constructed zeolitic MOF (SNNU-339), CO2 adsorption behavior is controllably changed from *CO2 to CO2* via the precise ligand-to-metal charge donation (LTMCD) regulation. It is confirmed that the high electronegativity of the coordinate ligand directly restricts the LTMCD, reduces the charge density on the metal sites, lowers the Gibbs free energy for CO2* adsorption, and leads to the transformation of CO2 adsorption mode from *CO2 to CO2*. Owing to the modulated CO2 adsorption behavior and regulated kinetics, SNNU-339 exhibits superior HCOOH selectivity (≈330% promotion, 85.6% Faradaic efficiency) and high CO2ER activity. The wide applicability of the proposed approach sheds light on the efficient CO2ER. This study provides a competitive strategy for rational catalyst design and underscores the significance of adsorption behavior tuning in electrocatalysis.

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.

Switching CO2 Electroreduction Pathways between Ethylene and Ethanol via Tuning Microenvironment of the Coating on Copper Nanofibers.

Engineering the microenvironment of electrode surface is one of the effective means to tune the reaction pathways in CO2RR. In this work, we prepared copper nanofibers with conductive polypyrrole coating by polymerization of pyrrole using polyvinyl pyrrolidone (PVP) as template. As a result, the obtained copper nanofibers Cu/Cu2+1O/SHNC, exhibited a superhydrophobic surface, which demonstrated very high selectivity for ethanol with a Faraday efficiency (FE) of 66.5% at -1.1 V vs reversible hydrogen electrode (RHE) in flow cell. However, the catalyst Cu/Cu2+1O/NC, which was prepared under the same conditions but without PVP, possessed a hydrophobic surface and exhibited high selectivity towards ethylene at the given potentials. The mechanism for switch of reaction pathways from ethylene to ethanol in CO2RR was studied. Incorporating pyrrolidone groups into the polymer coating results in the formation of a superhydrophobic surface. This surface weakens the hydrogen bonding interaction between interfacial water molecules and facilitates the transfer of CO2, thereby enhancing the local CO2/H2O ratio. The high coverage of *CO promotes the coupling of *CO and *CHO to form C2 intermediates, and reduces the reaction energy for the formation of *CHCHOH (ethanol path) at the interface. This ensures that the reaction pathway is directed towards ethanol.

Polyelectrolyte Additive-Modulated Interfacial Microenvironment Boosting CO2 Electrolysis in Acid.

Acidic CO2 electrolysis offers a promising strategy to achieve high carbon utilization and high energy efficiency. However, challenges still remain in suppressing the competitive hydrogen evolution reaction (HER) and improving product selectivity. Although high concentrations of potassium ions (K+) can suppress HER and accelerate CO2 reduction, they still inevitably suffer from salt precipitation problems. In this study, we demonstrate that the sulfonate-based polyelectrolyte, polystyrene sulfonate (PSS), enables to reconstruct the electrode-electrolyte interface to significantly enhance the acidic CO2 electrolysis. Mechanistic studies reveal that PSS induces high local K+ concentrations through the electrostatic interaction between PSS anions and K+. In situ spectroscopy reveals that PSS reshapes the interfacial hydrogen-bond (H-bond) network, which is attributed to the H-bonds between PSS anions and hydrated proton, as well as the steric hindrance of the additive molecules. This greatly weakens proton transfer kinetics and leads to the suppression of undesirable HER. As a result, a Faradaic efficiency of 93.9 % for CO can be achieved at 250 mA cm-2, simultaneous with a high single-pass carbon efficiency of 72.2 % on commercial Ag catalysts in acid. This study highlights the important role of the electrode-electrolyte interface induced by polyelectrolyte additives in promoting electrocatalytic reactions.

Mesostructure-Specific Configuration of *CO Adsorption for Selective CO2 Electroreduction to C2+ Products.

The multi-carbon (C2+) alcohols produced by electrochemical CO2 reduction, such as ethanol and n-propanol, are considered as indispensable liquid energy carriers. In most C-C coupling cases, however, the concomitant gaseous C2H4 product results in the low selectivity of C2+ alcohols. Here, we report rational construction of mesostructured CuO electrocatalysts, specifically mesoporous CuO (m-CuO) and cylindrical CuO (c-CuO), enables selective distribution of C2+ products. The m-CuO and c-CuO show similar selectivity towards total C2+ products (≥76 %), but the corresponding predominant products are C2+ alcohols (55 %) and C2H4 (52 %), respectively. The ordered mesostructure not only induces the surface hydrophobicity, but selectively tailors the adsorption configuration of *CO intermediate: m-CuO prefers bridged adsorption, whereas c-CuO favors top adsorption as revealed by in situ spectroscopies. Computational calculations unravel that bridged *CO adsorbate is prone to deep protonation into *OCH3 intermediate, thus accelerating the coupling of *CO and *OCH3 intermediates to generate C2+ alcohols; by contrast, top *CO adsorbate is apt to undergo conventional C-C coupling process to produce C2H4. This work illustrates selective C2+ products distribution via mesostructure manipulation, and paves a new path into the design of efficient electrocatalysts with tunable adsorption configuration of key intermediates for targeted products.

Anionic Metal-Organic Framework Derived Cu Catalyst for Selective CO2 Electroreduction to Hydrocarbons.

Metal-organic frameworks (MOFs)-related Cu materials are promising candidates for promoting electrochemical CO2 reduction to produce valuable chemical feedstocks. However, many MOF materials inevitable undergo reconstruction under reduction conditions; therefore, exploiting the restructuring of MOF materials is of importance for the rational design of high-performance catalyst targeting multi-carbon products (C2). Herein, a facile solvent process is choosed to fabricate HKUST-1 with an anionic framework (a-HKUST-1) and utilize it as a pre-catalyst for alkaline CO2RR. The a-HKUST-1 catalyst can be electrochemically reduced into Cu with significant structural reconstruction under operating reaction conditions. The anionic HKUST-1 derived Cu catalyst (aHD-Cu) delivers a FEC2H4 of 56% and FEC2 of ≈80% at -150 mA cm-2 in alkaline electrolyte. The resulting aHD-Cu catalyst has a high electrochemically active surface area and low coordinated sites. In situ Raman spectroscopy indicates that the aHD-Cu surface displays higher coverage of *CO intermediates, which favors the production of hydrocarbons.

Porous Bi Nanosheets Derived from ß-Bi2O3 for Efficient Electrocatalytic CO2 Reduction to Formate.

The electrochemical CO2 reduction reaction (ECO2RR) is a promising strategy for converting CO2 into high-value chemical products. However, the synthesis of effective and stable electrocatalysts capable of transforming CO2 into a specified product remains a huge challenge. Herein, we report a template-regulated strategy for the preparation of a Bi2O3-derived nanosheet catalyst with abundant porosity to achieve the expectantly efficient CO2-to-formate conversion. The resultant porous bismuth nanosheet (p-Bi) not only exhibited marked Faradaic efficiency of formate (FEformate), beyond 91% in a broad potential range from -0.75 to -1.1 V in the H-type cell, but also demonstrated an appreciable FEformate of 94% at a high current density of 262 mA cm-2 in the commercially important gas diffusion cell. State-of-the-art X-ray absorption near edge structure spectroscopy (XANES) and theoretical calculation unraveled the distinct formate production performance of the p-Bi catalyst, which was cocontributed by its smaller size, plentiful porous structure, and stronger Bi-O bond, thus accelerating the absorption of CO2 and promoting the subsequent formation of intermediates. This work provides an avenue to fabricate bismuth-based catalysts with high planar and porous morphologies for a broad portfolio of applications.

Photothermal Assisted Biomass Oxidation for Pairing Carbon Dioxide Electroreduction with Low Cell Potential.

Integrating anodic biomass valorization with carbon dioxide electroreduction (CO2RR) can produce value-added chemicals on both the cathode and anode; however, anodic oxidation still suffers from high overpotential. Herein, a photothermal-assisted method was developed to reduce the potential of 5-hydroxymethyl furfural (HMF) electrooxidation. Capitalizing on the copious oxygen vacancies, defective Co3O4 (D-Co3O4) exhibited a stronger photothermal effect, delivering a local temperature of 175.47 °C under near infrared light illumination. The photothermal assistance decreased the oxidation potential of HMF from 1.7 V over pristine Co3O4 to 1.37 V over D-Co3O4 to achieve a target current density of 30 mA cm-2, with 2,5-furandicarboxylic acid as the primary product. Mechanistic analysis disclosed that the photothermal effect did not change the HMF oxidation route but greatly enhanced the adsorption capacity of HMF. Meanwhile, faster electron transfer for direct HMF oxidation and the surface conversion to cobalt (oxy)hydroxide, which contributed to indirect HMF oxidation, was observed. Thus, rapid HMF conversion was realized, as evidenced by in situ surface-enhanced infrared spectroscopy. Upon coupling cathodic CO2RR with an atomically dispersed Ni-N/C catalyst, the Faradaic efficiencies of CO (cathode) and 2,5-furandicarboxylic acid (FDCA, anode) exceeded 90.0 % under a low cell potential of 1.77 V.

Selective CO2 Electroreduction to Multi-Carbon Products on Organic-Functionalized CuO Nanoparticles by Local Micro-Environment Modulation.

Surface functionalization of Cu-based catalysts has demonstrated promising potential for enhancing the electrochemical CO2 reduction reaction (CO2RR) toward multi-carbon (C2+) products, primarily by suppressing the parasitic hydrogen evolution reaction and facilitating a localized CO2/CO concentration at the electrode. Building upon this approach, we developed surface-functionalized catalysts with exceptional activity and selectivity for electrocatalytic CO2RR to C2+ in a neutral electrolyte. Employing CuO nanoparticles coated with hexaethynylbenzene organic molecules (HEB-CuO NPs), a remarkable C2+ Faradaic efficiency of nearly 90% was achieved at an unprecedented current density of 300 mA cm-2, and a high FE (> 80%) was maintained at a wide range of current densities (100-600 mA cm-2) in neutral environments using a flow cell. Furthermore, in a membrane electrode assembly (MEA) electrolyzer, 86.14% FEC2+ was achieved at a partial current density of 387.6 mA cm-2 while maintaining continuous operation for over 50 h at a current density of 200 mA cm-2. In-situ spectroscopy studies and molecular dynamics simulations reveal that reducing the coverage of coordinated K⋅H2O water increased the probability of intermediate reactants (CO) interacting with the surface, thereby promoting efficient C-C coupling and enhancing the yield of C2+ products. This advancement offers significant potential for optimizing local micro-environments for sustainable and highly efficient C2+ production.

Promoting CO2 Electroreduction to Hydrocarbon Products via Sulfur-Enhanced Proton Feeding in Atomically Precise Thiolate-Protected Cu Clusters.

Thiolate-protected Cu clusters with well-defined structures and stable low-coordinated Cu+ species exhibit remarkable potential for the CO2RR and are ideal model catalysts for establishing structure-electrocatalytic property relationships at the atomic level. However, extant Cu clusters employed in the CO2RR predominantly yield 2e- products. Herein, two model Cu4(MMI)4 and Cu8(MMI)4(tBuS)4 clusters (MMI=2-mercapto-1-methylimidazole) are prepared to investigate the synergistic effect of Cu+ and adjacent S sites on the CO2RR. Cu4(MMI)4 can reduce CO2 to deep-reduced products with a 91.0 % Faradaic efficiency (including 53.7 % for CH4) while maintaining remarkable stability. Conversely, Cu8(MMI)4(tBuS)4 shows a remarkable preference for C2+ products, achieving a maximum FE of 58.5 % with a C2+ current density of 152.1 mA⋅cm-2. In situ XAS and ex situ XPS spectra reveal the preservation of Cu+ species in Cu clusters during CO2RR, extensively enhancing the adsorption capacity of *CO intermediate. Moreover, kinetic analysis and theoretical calculations confirm that S sites facilitate H2O dissociation into *H species, which directly participate in the protonation process on adjacent Cu sites for the protonation of *CO to *CHO. This study highlights the important role of Cu-S dual sites in Cu clusters and provides mechanistic insights into the CO2RR pathway at the atomic level.

Electron Reservoir Effect of Adjacent Fe Nanoclusters Boosts Atomic Fe Active Sites on Porous Carbon for the Both Electrocatalytic Oxygen Reduction and CO2 Reduction Reaction.

Electrochemical oxygen reduction reaction (ORR) and carbon dioxide reduction reaction (CO2RR) are greatly significant in renewable energy-related devices and carbon-neutral closed cycle, while the development of robust and highly efficient electrocatalysts has remained challenges. Herein, a hybrid electrocatalyst, featuring axial N-coordinated Fe single atom sites on hierarchically N, P-codoped porous carbon support and Fe nanoclusters as electron reservoir (FeNCs/FeSAs-NPC), is fabricated via in situ thermal transformation of the precursor of a supramolecular polymer initiated by intermolecular hydrogen bonds co-assembly. The FeNCs/FeSAs-NPC catalyst manifests superior oxygen reduction activity with a half-wave potential of 0.91 V in alkaline solution, as well as high CO2 to CO Faraday efficiency (FE) of surpassing 90% in a wide potential window from -0.40 to -0.85 V, along with excellent electrochemical durability. Theoretical calculations indicate that the electron reservoir effect of Fe nanoclusters can trigger the electron redistribution of the atomic Fe moieties, facilitating the activation of O2 and CO2 molecules, lowering the energy barriers for rate-determining step, and thus contributing to the accelerated ORR and CO2RR kinetics. This work offers an effective design of electron coupling catalysts that have advanced single atoms coexisting with nanoclusters for efficient ORR and CO2RR.

Selectivity of a Copper Oxide CO2 Reduction Electrocatalyst Shifted by a Bioinspired pH-Sensitive Polymer.

A bioinspired polymeric membrane capable of shifting the selectivity of a copper oxide electrocatalyst in the CO2 reduction reaction is described. The membrane is deposited on top of copper oxide thin films from wet deposition techniques under controlled conditions of humidity and self-assembles into an arranged network of micrometer-sized pores throughout the polymer cross-section. The membrane was composed of a block copolymer with a precisely controlled ratio of poly-4-vinylpyridine and poly(methyl methacrylate) blocks (PMMA-b-P4VP). The intrinsic hydrophobicity, together with the porous nature of the membrane's surface, induces a Cassie-Baxter wetting transition above neutral pH, resulting in water repulsion from the catalyst surface. As a consequence, the catalyst's surface is shielded from surrounding water molecules under CO2 electroreduction reaction conditions, and CO2 molecules are preferentially located in the vicinity of the catalytically active area. The CO2 reduction reaction is therefore kinetically favored over the hydrogen evolution reaction (HER).