Activating inert antimony for selective CO2 electroreduction to formate via bimetallic interactions

Abstract

Antimony (Sb) as a low-toxic and cost-effective metal is a promising material to catalyse CO2 electroreduction to formate with practical viability. However, monometallic Sb suffers from intrinsically low catalytic activity and the competing hydrogen evolution. Here, we report nanoporous Sb-Bi alloys for substantially improving the catalytic activity of Sb and suppressing hydrogen evolution. The optimal Sb-Bi alloy exhibits a maximum Faradaic efficiency of 95.8 % toward formate production, surpassing the 11.6 % of monometallic Sb counterpart. Operating the catalyst in the flow cell demonstrates a formate partial current density of 734 mA cm−2 and cathodic energy efficiency of 59 % at a moderate overpotential of 800 mV, representing a record formate-production performance so far. Experimental and theoretical studies indicate that the Sb-Bi interactions activate Sb sites to selectively stabilize *OCHO intermediates, facilitating CO2-to-formate conversion. This work offers insights in manipulating bimetallic interactions to transform inert materials into active catalysts for efficient electrocatalysis.