CoNiO2 as a novel water oxidation cocatalyst to enhance PEC water splitting performance of BiVO4

A strategy is proposed for modifying BiVO4 photoanode with CoNiO2 as a novel water oxidation cocatalyst to enhance PEC water splitting performance. The results show that CoNiO2 has the following functions: reducing photogenerated charge recombination centers; providing trapping sites to promote charge separation; improving the stability of the overall system; providing more active sites; and offering a lower overpotential. The BiVO4/CoNiO2 photoanode has a higher photocurrent density (1.16 mA cm−2 at 1.23 V vs. RHE), a lower onset potential (∼0.06 V vs. RHE), a larger IPCE (34.37%) and ABPE (0.163%), better stability and good rates of hydrogen evolution (0.0148 μmol cm−2 min−1) and oxygen evolution (0.0076 μmol cm−2 min−1). The strategy provides promising prospects for achieving efficient PEC water splitting performance using water oxidation cocatalysts.