One-Step phosphorus doping integrated vacancy engineering for efficient carbon dioxide electrochemical reduction

Vacancy engineering of electrocatalysts is recognized as an effective approach to improve CO₂ activation. Element doping, which enhances the electrical conductivity of electrocatalysts, can elevate the current density in the CO₂ reduction reaction (CO₂RR). Herein, we present a facile strategy to integrate elemental doping and vacancy engineering in one step. We select tin disulfide (SnS₂) nanosheets as the parent electrocatalyst and phosphorus (P) as the doping element. Substituting the lower-valence S²⁻ with the higher-valence P³⁻, S vacancies are generated, leading to the formation of P-doped SnS_2-x. The combination of P doping with S vacancies (PDSVs) induces significant charge redistribution and electron accumulation, leading to catalytically active sites that lower the activation barrier and accelerate reduction kinetics, outperforming SnS_2-x with S vacancies alone. Moreover, PDSVs narrow the band gap and introduce a new band at the Fermi level, showing a carrier density 5.9 times that of SnS₂. As a result, P-SnS_2-x delivers a current density of −31.4 mA cm⁻² for HCOOH production at −1.2 V vs. the reversible hydrogen electrode. A Faraday efficiency >80 % for HCOOH is demonstrated over a large potential range. This work provides a one-step strategy for simultaneously achieving element doping and vacancy engineering in electrocatalysts.