Sulfhydryl modified silver-titanium oxide to effectively and stably promote the electrocatalytic reduction of carbon dioxide to CO†

Abstract

Under ambient conditions, one efficient way to transform the greenhouse gas carbon dioxide (CO₂) into carbon-containing compounds is the electrocatalytic CO₂ reduction reaction (CO₂RR). However, electrocatalysis depends on the aid of the liquid phase interface, and the competing hydrogen evolution reaction (HER) inevitably occurs, which greatly reduces the efficiency of the CO₂RR. As a result, creating effective hydrogen suppression catalysts with excellent stability and selectivity is a difficult but vital undertaking. Scholars have focused much work on developing efficient synergistic interactions between silver and metal oxides; however, the requirement of high faradaic efficiency (FE) cannot be met by depending only on the synergistic interaction between silver metal and metal oxides. Therefore, this paper proposed the idea of modifying silver with exogenous ligands and then combining it with metal oxides to form new composite materials. To increase carbon monoxide (CO) selectivity and cathodic energy efficiency, a sulfhydryl ligand modified silver-titanium dioxide catalyst (Ag/AgS–TiO₂) was prepared and reported in this work. It demonstrated excellent CO selectivity (>90%) as a CO₂RR catalyst throughout a broad electrode potential range of −1.1 to −1.4 V (vs. the reversible hydrogen electrode (RHE)); its cathodic energy efficiency reached 51.7%, surpassing that of the majority of silver-based electrocatalysts. The competitive hydrogen evolution process was inhibited, *CO was formed more easily, and the essential intermediates for CO₂ reduction were optimized with the presence of sulfhydryl ligands. This work presented a novel approach to the construction of CO₂RR catalysts that combine TiO₂ and silver.