Electrocatalytic reduction of CO2 to multicarbon products is a potential strategy to solve the energy crisis while achieving carbon neutrality. To improve the efficiency of multicarbon products in Cu-based catalysts, optimizing the *CO adsorption and reducing the energy barrier for carbon–carbon (C–C) coupling are essential features. In this work, a strong local electric field is obtained by regulating the arrangement of Cu nanoneedle arrays (CuNNAs). CO2 reduction performance tests indicate that an ordered nanoneedle array reaches a 59% Faraday efficiency for multicarbon products (FEC2) at −1.2 V (vs RHE), compared to a FEC2 of 20% for a disordered nanoneedle array (CuNNs). As such, the very high and local electric fields achieved by an ordered Cu nanoneedle array leads to the accumulation of K+ ions, which benefit both *CO adsorption and C–C coupling. Our results contribute to the design of highly efficient catalysts for multicarbon products.

Antimony sulfide (Sb2S3) is an emerging photovoltaic material that comprises earth-abundant, non-toxic constituents and has a high absorption coefficient (>104 cm−1). Nevertheless, the serious bulk recombination phenomenon and the slow electrochemical reaction kinetics on the surface of Sb2S3 electrode restrict its application in the photoelectrochemical (PEC) water splitting. Herein, we have designed a polyaniline (PANI)/Sb2S3 p-n junction photoanode successfully to address these issues. With the modification of in-situ anchored PANI, the composite electrode exhibits enhanced light-absorption and accelerated charge transfer efficiency. As a result, the photocurrent density of optimized PANI/Sb2S3 photoanode is about twice of pristine Sb2S3, being a promising material for PEC water splitting.