Charge Transport Enhancement in BiVO 4 Photoanode for Efficient Solar Water Oxidation.

Photoelectrochemical (PEC) water splitting in a pH-neutral electrolyte has attracted more and more attention in the field of sustainable energy. Bismuth vanadate (BiVO 4 ) is a highly promising photoanode material for PEC water splitting. Additionally, cobaltous phosphate (CoPi) is a material that can be synthesized from Earth's rich materials and operates stably in pH-neutral conditions. Herein, we propose a strategy to enhance the charge transport ability and improve PEC performance by electrodepositing the in situ synthesis of a CoPi layer on the BiVO 4 . With the CoPi co-catalyst, the water oxidation reaction can be accelerated and charge recombination centers are effectively passivated on BiVO 4 . The BiVO 4 /CoPi photoanode shows a significantly enhanced photocurrent density ( J ph ) and applied bias photon-to-current efficiency (ABPE), which are 1.8 and 3.2 times higher than those of a single BiVO 4 layer, respectively. Finally, the FTO/BiVO 4 /CoPi photoanode displays a photocurrent density of 1.39 mA cm -2 at 1.23 V RHE , an onset potential ( V on ) of 0.30 V RHE , and an ABPE of 0.45%, paving a potential path for future hydrogen evolution by solar-driven water splitting.