Oxyhydroxide Species Enhances CO₂ Electroreduction\nto CO on Ag via Coelectrolysis with O₂

Abstract

Ag and Au are efficient monometallic\nelectrocatalysts for the CO₂ reduction reaction (CO₂RR) to CO. Recent preoxidation\ntreatments on Ag and Au have been shown to effectively improve their\nreactivity in CO production. However, the mechanism underlying the\nimprovements remains controversial. The challenges in probing the\nsurface speciation under reaction conditions hinder the efforts to\nbe made for correlating the catalyst surface speciation with its performance.\nHerein, we combine in situ surface-enhanced Raman spectroscopy and\nreactivity measurements to investigate the coelectrolysis of CO₂ and O₂ demonstrating that the in-situ-formed surface\noxyhydroxyl species on Ag can significantly enhance the CO production\nrate (>80 fold). In contrast, no surface oxyhydroxyl species was\nobserved\non Au in coelectrolysis with O₂, which was accompanied\nby much less significant enhancement in the CO activity (<3-fold).\nOur work highlights the impact of catalyst surface speciation on the\nCO₂RR performance and opens up a promising route for designing\nefficient CO₂RR catalysts. We believe the findings presented\nin our work point out a fruitful strategy to design an advanced catalyst\nand reaction scheme to achieve efficient CO₂RR.