Electrochemically Driven Interfacial Transformation For High‐Performing Solar‐To‐Fuel Electrocatalytic Conversion

Abstract The carbon dioxide reduction reaction (CO₂RR) suffers from poor selectivity with low Faradaic efficiency and limited current density due to the lack of advanced electrocatalysts. Herein, it is demonstrated that the electrochemically driven interfacial transformation of bismuth sulfide (Bi₂S₃) nanorods enables the in situ formation of a 3D bismuth nanosheet network (BiNN) on functionalized carbon fibers (BiNN‐CFs). Notably, the formation of an ideal heterojunction with self‐driven charge migration facilitates the composition conversion with rapid reduction of Bi₂S₃ nanorods in seconds. The functionalization of CFs via Joule heating of the polytetrafluoroethylene coating induces an interfacial interaction for the simultaneous morphology evolution into the hierarchical BiNN via the recrystallization process. More importantly, the hierarchical BiNN‐CFs display improved performance for the CO₂RR, including reasonable selectivity for formate generation (≈92%) in the broad potential range, a large partial current density of 419 mA cm^–2, and good long‐term stability. Theoretical understanding elucidates that the lattice distortion tunes the p‐band center for optimizing the intermediate adsorption, and thus improving the electrocatalytic activity. Of particular note, the solar‐driven CO₂–H₂O full cell also demonstrates a promising energy conversion efficiency of 13.3%. These advances demonstrate the large space to optimize electrocatalysis that stems from the rational regulation of interfacial structure and properties.