Remarkable Enhancement of Bismuth Nanosphere Catalyst Activity for the Conversion of Electrocatalytic CO₂ to Formate by Bromine Doping

Driven by renewable energy, using electrocatalysis to reduce carbon dioxide (CO 2 ) to chemicals is a key technology. It could dim global carbon emissions and promote the carbon cycle. Here, we reported an approach to prepare a Br-doped Bi nanosphere (Br-doped Bi NSP) catalyst for the preparation of formate by electrochemical conversion of CO 2 . The synthesized Br-doped Bi NSP catalyst manifests high selectivity toward HCOOH. At the applied potential of −0.9 V versus reversible hydrogen electrode, it could achieve a maximum FE HCOOH of 98%. It can remain constant, and the degradation is negligible in continuous electrolysis for 9 h. The excellent CO 2 reduction performance is due to the electron richness at the surface of Br-doped Bi NSP induced by the electron transfer between Bi and Br. Density functional theory calculations and in situ attenuated total reflectance–Fourier transform infrared measurements were used to predict the underlying catalyst action’s pathway. It can be concluded that the introduction of Br is advantageous to the *OCHO formation, which is conducive to the reduction of the determination step. This research could provide a meaningful view into anion-doping effects to enable effiective electrocatalytic material that selectively reduces carbon dioxide into valuable products.