Bi₂S₃ nanorods grown on multiwalled carbon nanotubes as highly active catalysts for CO₂ electroreduction to formate

Bi-based materials are promising electrocatalysts for CO₂ reduction but one of the key technological hurdles is the design of stable, active and affordable Bi-based catalysts over a wide potential range. Herein, Bi₂S₃/CNTs nanocomposites are constructed by anchoring bismuth sulfide (Bi₂S₃) nanorods onto the multiwalled carbon nanotubes (CNTs) and utilizing them in electrocatalytic CO₂ reduction. CNTs, as a support, not only guarantee the conductivity and dispersibility of Bi₂S₃ nanorods but also improve the electrolyte infiltration and optimize the electronic structure of the Bi₂S₃. As expected, the Bi₂S₃/CNTs nanocomposite exhibits a faradaic efficiency for HCOO^- (FE_HCOO-) of 99.3% with a current density of -20.3 mA cm^-2 at -0.91 V vs. RHE. The FE_HCOO- is stably maintained at over > 91% in a wide potential window from -0.71 V to -1.31 V. Theoretical calculation analyses reveal that the strong interaction between Bi₂S₃ and CNTs is conductive to decreasing the energy barrier of *OCHO, stabilizing the intermediate *OCHO, and inhibiting the hydrogen evolution reaction. The current study provides an insightful understanding of the mechanism of the CO₂ electroreduction reaction, and paves a new way for developing superior and affordable electrocatalysts.