Electrochemical Fabrication and Reactivation of Nanoporous Gold with Abundant Surface Steps for CO₂ Reduction

Distinct from bulk materials, dealloyed nanoporous metals possess a large electrochemical surface area and abundant surface steps that are active for electrochemical reactions. Herein we fabricate a nanoporous gold electrocatalyst by electrochemical dealloying of potential cycling, which enables reducing carbon dioxide to carbon monoxide with a Faradaic efficiency of up to 98% at an overpotential of 390 mV. Pb-upd measurements verify that the high activity stems from the high density of step/kink sites with geometrically needed high-index facets on the curved internal surface. Moreover, a combination of X-ray photoelectron spectroscopy and in situ stripping voltammograms reveals that catalysis decay during long-term stability test results from the reduction of surface step/kink sites and the deposition of metal impurities (Zn, Pb, and Cu). The catalytic performance of the deactivated electrode can be recovered by applying potential cycling, which can restore the fractions of step/kink sites and remove surface metal impurities simultaneously.