Fabrication of Cocatalyst NiO-Modified BiVO Composites for Enhanced Photoelectrochemical Performances.

In this work, NiO modified BiVO (BiVO/NiO) nanocomposite was synthesized using hydrothermal and calcination method. The composite of BiVO/NiO, further employed as a low-overpotential photoanode, was consisted of BiVO nanoparticles and NiO nanosheets, in which the BiVO nanoelectrode served as the matrix for the attachment of NiO nanosheets. Photoelectrochemical (PEC) tests show that BiVO/NiO displayed improved PEC performance compared with pure BiVO. The BiVO/NiO photoanode delivers a photocurrent density of 1.2 mA/cm at 1.23 V vs. RHE in a NaSO electrolyte under an AM 1.5G solar simulator, which is 0.3 mA/cm higher than pure BiVO photoanode. Meanwhile, the onset potential also generates a 350 mV cathodic shift. The enhanced performance of the BiVO/NiO nanocomposite is attributed to NiO unique lamellar structure capable of providing a large number of active sites. Measurements of electrochemical impedance spectra (EIS) and the incident photon-to-current efficiency (IPCE) illustrate that the enhanced PEC activities are ascribed to the improved charge carrier separation/transport and the promoted water oxidation kinetics furnished by the decoration of NiO cocatalyst.