Efficient electroreduction of carbon dioxide to formate enabled by bismuth nanosheets enriched dual V Bi 0 vacancy.

The electrocatalytic reduction of carbon dioxide (CO ₂ ER) into formate presents a compelling solution for mitigating dependence on fossil energy and green utilization of CO ₂ . Bismuth (Bi) has been gaining recognition as a promising catalyst material for the CO ₂ ER to formate. The performance of Bi catalysts (named as Bi-V) can be significantly improved when they possess single metal atom vacancy. However, creating larger-sized metal atom vacancies within Bi catalysts remains a significant challenge. In this work, Bi nanosheets with dual V _Bi ⁰ vacancy (Bi-DV) were synthesized utilizing in situ electrochemical transformation, using BiOBr nanosheets with triple vacancy associates (V _Bi ^″' V _O ^·· V _Bi ^″' , V _Bi ^″' and V _O ^·· denote the Bi ³⁺ and O ^2- vacancy, respectively) as a template. The obtained Bi-DV achieved higher CO ₂ ER activity than Bi-V, showing Faradaic efficiency for formate production of >92% from -0.9 to -1.2 V _RHE in an H-type cell, and the partial current density of formate reached up to 755 mA/cm ² in a flow cell. The comprehensive characterizations coupled with density functional theory calculations demonstrate that the dual V _Bi ⁰ vacancy on the surface of Bi-DV expedite the reaction kinetics toward CO ₂ ER, by reducing the thermodynamic barrier of *OCHO intermediate formation. This research provides critical insights into the potential of large atom vacancies to enhance electrocatalysis performance.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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