Promoting electrocatalytic CO<sub>2</sub> reduction to formate via sulfur-boosting water activation on indium surfaces.

Ma, Wenchao; Xie, Shunji; Zhang, Xia-Guang; Sun, Fanfei; Kang, Jincan; Jiang, Zheng; Zhang, Qinghong; Wu, De-Yin et al. · Nat Commun · 2019

basic_science · Level V

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Abstract

Electrocatalytic reduction of CO<sub>2</sub> to fuels and chemicals is one of the most attractive routes for CO<sub>2</sub> utilization. Current catalysts suffer from low faradaic efficiency of a CO<sub>2</sub>-reduction product at high current density (or reaction rate). Here, we report that a sulfur-doped indium catalyst exhibits high faradaic efficiency of formate (>85%) in a broad range of current density (25-100 mA cm<sup>-2</sup>) for electrocatalytic CO<sub>2</sub> reduction in aqueous media. The formation rate of formate reaches 1449 μmol h<sup>-1</sup> cm<sup>-2</sup> with 93% faradaic efficiency, the highest value reported to date. Our studies suggest that sulfur accelerates CO<sub>2</sub> reduction by a unique mechanism. Sulfur enhances the activation of water, forming hydrogen species that can readily react with CO<sub>2</sub> to produce formate. The promoting effect of chalcogen modifiers can be extended to other metal catalysts. This work offers a simple and useful strategy for designing both active and selective electrocatalysts for CO<sub>2</sub> reduction.