Synergistic High-Efficiency Photoelectrochemical Water Splitting via Type-II Heterojunction MW:BVO/CeO₂ Coupled with Ultrathin NiFeOOH

In order to solve the problem of slow water oxidation kinetics and charge complexation of the BiVO 4 photoanode, CeO 2 octahedral nanomaterials doped with different amounts of NaH 2 PO 4 (COP3) were synthesized by a hydrothermal method in one step. CeO 2 -based materials have been widely studied in the fields of organic catalysis, photocatalysis to decompose water, and photodegradation of organic pollutants, showing excellent photocatalytic properties. The heterostructure formed by MW:BVO and COP3 (doped with 0.002 g of NaH 2 PO 4 ) expands the light absorption range and accelerates the separation of the internal carriers. In order to further improve the photocatalytic performance, the MW:BVO/COP3@NiFeOOH (immersion time of 1 h and pH = 8, respectively) composite was prepared by introducing NiFeOOH. As a metal oxide coating additive, NiFeOOH can rapidly capture holes and effectively use these holes for water oxidation on the photoelectrode surface through a cyclic catalytic process. In addition, MW:BVO/COP3@NiFeOOH nanocomposites can effectively increase the active surface area and accelerate the interfacial charge transfer. The final prepared MW:BVO/COP3@NiFeOOH nanocomposites showed excellent photocurrent density (4.8 mA cm –2 at 1.23 V vs RHE) in LSV tests due to the efficient separation and transfer of photogenerated carriers. It can be seen that the interaction between MW:BVO, COP3, and NiFeOOH not only improves the performance of this new class of materials but also highlights the importance of COP3 as an important component worthy of further study.