Decorating the Cocatalyst Membrane with Coordinated Tannic Acid and Ternary Metal for Advancing Photoelectrochemical Performance of F-Doped Hematite Photoanodes

The advancement of photoelectrochemical water splitting oxygen evolution technology is the key to improving the solar-hydrogen conversion efficiency. The theoretically highly active hematite-based photoanode still requires modification from inside to outside to conquer ultrafast carrier recombination and a high reaction barrier. Herein, we report a uniform and ultrathin cocatalyst with coordinated tannic acid, Ni, Fe, and Co (TA–NFC), for enhancing photoelectrochemical performance of the F-doped Fe 2 O 3 nanorod (NR) photoanode. The F-doping in the structure fulfills more carrier density and lower charge transfer resistance for accelerating photogenerated electron and hole separation. Furthermore, the TA–NFC cocatalyst on the surface assists hole injection and supports faster water oxidation kinetic. Ultimately, the photocurrent density of F–Fe 2 O 3 @TA–NFC NRs sharply increased up to 3.02 mA/cm 2 at 1.23 V versus RHE, and the applied-bias photon-to-current efficiency reached 0.33% maximum at low bias. This work may supply a novel and promising design scheme for improving the intrinsic photoelectrochemical activity of semiconductor-based photoanodes.