Boron Dopant Modulated Electron Localization of Tin Oxide for Efficient Electrochemical CO 2 Reduction to Formate.

Sn-based electrocatalysts have great economic potential in the reduction of CO 2 to HCOOH, while they still suffer from low current density, dissatisfactory selectivity, and poor stability. Inspired by electronic modification engineering, boron-doped SnO 2 nanospheres (B-SnO 2 ) are successfully synthesized to achieve high-efficiency CO 2 reduction reaction (CO 2 RR). It is found that the introduction of boron dopants can increase the number of active sites and facilitate the formation of the electron-rich Sn sites in its structure, thus enhancing the activation of CO 2 molecules and reducing the energy barrier of *OCHO intermediates on the SnO 2 surface. Thus, the B-doped SnO 2 electrocatalyst exhibits a remarkable FE HCOOH above 90% within a broad potential window of -0.7 to -1.3 V versus reversible hydrogen electrode (RHE) (600 mV) and obtains the maximum value of 95.1% (the partial current density of HCOOH is 42.35 mA cm -2 ) at -1 V versus RHE. In conclusion, this work provides a novel strategy for optimizing the intrinsic properties of electrocatalysts for CO 2 RR by the method of tuning the electronic structure.