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

A copper-based catalyst Cu x Si (3 < x < 5) was prepared using chemical vapor deposition (CVD) of butylsilane (BuSiH 3 ) 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 CO 2 reduction reactions (eCO 2 RR). We observed a high selectivity towards ethanol (∼79%) in neutral CO 2 -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 CO 2 conversion to high-value multi-carbon products. Copper silicide based electrocatalytical system produces distinguishable main products depending on electrolyte's pH value with both high selectivity and faradaic efficiency. No material deterioration is observed even after 700 hours of operation.