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Tuning the selectivity of CO2 electroreduction reaction (CO2RR) solely by changing electrolyte is a very attractive topic. In this study, we conducted CO2RR in different aqueous electrolytes over bulk metal electrodes. It was discovered that controlled CO2RR could be achieved by modulating cations in the electrochemical double layer. Specifically, ionic liquid cations in the electrolyte significantly inhibits the hydrogen evolution reaction (HER), while yielding high Faraday efficiencies toward CO (FECO) or formate (FEformate) depending on the alkali metal cations. For example, the product could be switched from CO (FECO=97.3 %) to formate (FEformate=93.5 %) by changing the electrolyte from 0.1 M KBr‐0.5 M 1‐octyl‐3‐methylimidazolium bromide (OmimBr) to 0.1 M CsBr‐0.5 M OmimBr aqueous solutions over pristine Cu foil electrode. In situ spectroscopy and theoretical calculations reveal that the ordered structure generated by the assembly of Omim+ under an applied negative potential alters the hydrogen bonding structure of the interfacial water, thereby inhibiting the HER. The difference in selectivity in the presence of different cations is attributed to the hydrogen bonding effect caused by Omim+, which alters the solvated structure of the alkali metal cations and thus affects the stabilization of intermediates of different pathways. [ABSTRACT FROM AUTHOR]

Regulating the binding effect between the surface of an electrode material and reaction intermediates is essential in highly efficient CO2 electro‐reduction to produce high‐value multicarbon (C2+) compounds. Theoretical study reveals that lattice tensile strain in single‐component Cu catalysts can reduce the dipole–dipole repulsion between *CO intermediates and promotes *OH adsorption, and the high *CO and *OH coverage decreases the energy barrier for C−C coupling. In this work, Cu catalysts with varying lattice tensile strain were fabricated by electro‐reducing CuO precursors with different crystallinity, without adding any extra components. The as‐prepared single‐component Cu catalysts were used for CO2 electro‐reduction, and it is discovered that the lattice tensile strain in Cu could enhance the Faradaic efficiency (FE) of C2+ products effectively. Especially, the as‐prepared CuTPA catalyst with high lattice tensile strain achieves a FEC2+ of 90.9 % at −1.25 V vs. RHE with a partial current density of 486.1 mA cm−2. [ABSTRACT FROM AUTHOR]

Modulation of the microenvironment on the electrode surface is one of the effective means to improve the efficiency of electrocatalytic carbon dioxide reduction (eCO2RR). To achieve high conversion rates, the phase boundary at the electrode surface should be finely controlled to overcome the limitation of CO2 solubility in the aqueous electrolyte. Herein, we developed a simple and efficient method to structure electrocatalyst with a superhydrophobic surface microenvironment by one‐step co‐electrodeposition of Cu and polytetrafluoroethylene (PTFE) on carbon paper. The super‐hydrophobic Cu‐based electrode displayed a high ethylene (C2H4) selectivity with a Faraday efficiency (FE) of 67.3 % at −1.25 V vs. reversible hydrogen electrode (RHE) in an H‐type cell, which is 2.5 times higher than a regular Cu electrode without PTFE. By using PTFE as a surface modifier, the activity of eCO2RR is enhanced and water (proton) adsorption is inhibited. This strategy has the potential to be applied to other gas‐conversion electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) presents a promising approach for producing valuable chemicals and fuels, offering a dual benefit in terms of environmental preservation and the efficient utilization of carbon resources. In this work, we proposed a stepwise electrodeposition method to prepare Cu−Pb bimetallic heterojunction catalyst on polyaniline‐modified carbon paper (PANI‐CuPb‐x), where x is the electrodeposition times(min). Among the studied catalysts, the electrode electrodeposited for 2 min (PANI‐CuPb‐2) exhibited a remarkable performance during the electrocatalysis CO2 to multicarbon (C2+) products process, achieving a Faraday efficiency (FE) of 81.46 % and a partial current density of 15.41 mA cm−2 at −1.2 V (vs. RHE) in an H‐type cell. The detailed study demonstrated that introducing Pb could effectively improve the formation of COOH*inhibit hydrogen evolution reaction (HER). Furthermore, the heterojunction structure in the catalysts facilitated C−C coupling of the generated C1 intermediate species, which enhanced the CO2 to C2+ reaction. [ABSTRACT FROM AUTHOR]