MOF derived NiO thin film formed p-n heterojunction with BiVO4 photoelectrode for enhancement of PEC performance

Metal‐organic frameworks (MOFs) derived metal oxides with large surface and more metal active sites were beneficial for photoelectrochemical (PEC) water splitting. In this work, we used a novel and easy method for the Ni-MOF attached on BiVO4 photoelectrode surface by electrostatic attraction, afterwards the Ni-MOF/BiVO4 photoelectrodes were annealed at muffle to obtain MOF derived NiO/BiVO4 p-n heterojunction composite photoelectrodes. The thickness of NiO thin film with ultrathin structure was tested by atomic force microscopy (AFM). The photoelectrochemical (PEC) performance of NiO/BiVO4 composites photoelectrodes for water splitting was enhanced compared to the pure BiVO4 photoelectrode. The best NiO/BiVO4 photoelectrodes with about 70 nm thickness of NiO thin film showed the max photocurrent density with 1.94 mA/cm2 (1.23 V vs RHE) which was about 4.2 times than the pure BiVO4 with 0.46 mA/cm2 (1.23 V vs RHE). The charge injection and separation efficiency of NiO/BiVO4 photoelectrodes enhancement indicate that the NiO as a co-catalysis and form p-n heterojunction has improved the photoexcited carrier mobility which was benefited for the PEC performance of water splitting.