A robust and high performance copper silicide catalyst for electrochemical CO2 reduction

Abstract

A copper-based catalyst Cu_xSi (3 < x < 5) was prepared using chemical vapor deposition (CVD) of butylsilane (BuSiH₃) on copper substrates. By varying the precursor flow, we obtained two catalyst variants, one with and one without a SiC_x shell. Both variants exhibited large specific areas, owing to the presence of grown nanostructures such as nanoplatelets, nanowires, nanoribbons, and microwires. Remarkably, the catalytic performance of both variants remained stable even after 720 hours of continuous operation. The porous and thick catalyst layer (over a hundred micrometers) on the substrate significantly increased the residence time of intermediates during the electrochemical CO₂ reduction reactions (eCO₂RR). We observed a high selectivity towards ethanol (∼79%) in neutral CO₂-saturated electrolytes and a high selectivity towards acetic acid (∼72%) in alkaline electrolytes. Importantly, the ratio between generated ethanol and acetate could be shifted by adjusting the pH and applied potential. This work thus establishes copper silicides as robust and promising electrocatalysts for selective CO₂ conversion to high-value multi-carbon products.