In-situ cation-exchange strategy for engineering single-atomic Co on TiO2 photoanode toward efficient and durable solar water splitting

Single-atomic catalysts (SACs) have been emerging as one of potential candidates in catalysts, owing to their unique merits with extremely high specific surface area as well as remarkably exposed active sites. Herein, we develop an in-situ gas-phase cation exchange strategy for engineering single-atomic Co on the surface of TiO2 photoanode toward solar water splitting. It is verified that the atomically-dispersed Co with Co-O coordination could optimize the surface electronic structures, enhance the light absorption, promote the photoinduced charge transfer, lower the reaction barrier and accelerate the reaction kinetics, which consequently enable the overall improved photoelectrochemical (PEC) behaviors for photoanodes. As a proof of concept, the as-constructed TiO2-based photoanodes deliver robust stability up to 100 h and a photocurrent density up to 1.47 mA cm−2 at 1.23 V vs. RHE, which are superior to those of pristine TiO2, representing their significance for potential applications.