Promoting charge carrier utilization by integrating layered double hydroxide nanosheet arrays with porous BiVO4 photoanode for efficient photoelectrochemical water splitting

The increasing exploration of renewable and clean power sources have driven the development of highly active materials for photoelectrochemical (PEC) water splitting. However, it is still a great challenge to enhance the charge utilization. Herein, we report a facile method to fabricate composite photoanode with porous BiVO4 film as the photon absorber and layered double hydroxide (LDH) nanosheet arrays as the oxygen-evolution cocatalysts (OECs). The as-prepared BiVO4/NiFe-LDH photoanode shows an excellent performance for PEC water splitting benefitting from the synergistic effect of the superior charge separation efficiency facilitated by porous BiVO4 film and the excellent water oxidation activity resulting from LDH nanosheet arrays. A photocurrent density is 4.02 mA cm−2 at 1.23 V vs. the reversible hydrogen electrode (RHE). Furthermore, the O2 evolution rate at the surface of BiVO4/NiFe-LDH photoanode is as high as 29.6 μmol h−1 cm−2 and the high activity for water oxidation is maintained for over 30 h. Impressively, the performance of the as-fabricated composite photoanode for PEC water splitting can be further enhanced through incorporating a certain amount of Co2+ cation into NiFe-LDH as OEC. The photocurrent density is achieved up to 4.45 mA cm−2 at 1.23 V vs. RHE. This value is the highest yet reported for un-doped BiVO4-based photoanodes so far.