For steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

Electrochemical reduction of CO 2 on copper-based catalysts has become a promising strategy to mitigate greenhouse gas emissions and gain valuable chemicals and fuels. Unfortunately, however, the generally low product selectivity of the process decreases the industrial competitiveness compared to the established large-scale chemical processes. Here, we present random solid solution Cu 1−x Ni x alloy catalysts that, due to their full miscibility, enable a systematic modulation of adsorption energies. In particular, we find that these catalysts lead to an increase of hydrogen evolution with the Ni content, which correlates with a significant increase of the selectivity for methane formation relative to C 2 products such as ethylene and ethanol. From experimental and theoretical insights, we find the increased hydrogen atom coverage to facilitate Langmuir−Hinshelwood-like hydrogenation of surface intermediates, giving an impressive almost 2 orders of magnitude increase in the CH 4 to C 2 H 4 + C 2 H 5 OH selectivity on Cu 0.87 Ni 0.13 at −300 mA cm −2 . This study provides important insights and design concepts for the tunability of product selectivity for electrochemical CO 2 reduction that will help to pave the way toward industrially competitive electrocatalyst materials.

Cu acetate/PAN nanofibers were transformed into porous C nanofibers with doped N and Cu particles, via O2 partial pressure-controlled calcination. N atoms next to Cu trigger the CO2RR by increasing the amount of CO* on the Cu, lowering the energy needed for CO dimerization.

The evaluation of catalysts on gas diffusion electrodes (GDEs) have propelled the progress of electrochemical CO 2 reduction reaction (CO 2 RR) at industry-relevant activities. However, high experimental complexities exist in GDE-based flow electrolyzers, whereby various experimental factors can influence the evaluation of catalytic CO 2 RR performances. Not accounting for these experimental factors could result in inconsistent conclusions and thus hinder rational catalyst developments. This Perspective highlights a range of experimental factors that can affect the performance metrics for electrocatalysts. Specifically, the product faradaic efficiency can be influenced by the overestimation of the effluent gas flow rate, unaccounted losses of products, and unintended alteration of microenvironments. In addition, cathodic voltage can be inaccurately determined due to the unaccounted dynamic changes in uncompensated resistance. By raising awareness of these potential pitfalls and establishing appropriate protocols, we foresee a more meaningful benchmarking of catalytic performances across the literature.