Charge Transport Enhancement in BiVO[sub.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[sub.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[sub.4]. With the CoPi co-catalyst, the water oxidation reaction can be accelerated and charge recombination centers are effectively passivated on BiVO[sub.4]. The BiVO[sub.4]/CoPi photoanode shows a significantly enhanced photocurrent density (J[sub.ph]) and applied bias photon-to-current efficiency (ABPE), which are 1.8 and 3.2 times higher than those of a single BiVO[sub.4] layer, respectively. Finally, the FTO/BiVO[sub.4]/CoPi photoanode displays a photocurrent density of 1.39 mA cm[sup.−2] at 1.23 V[sub.RHE], an onset potential (V[sub.on]) of 0.30 V[sub.RHE], and an ABPE of 0.45%, paving a potential path for future hydrogen evolution by solar-driven water splitting.