Accelerated photoelectrochemical oxygen evolution over a BaTaO2N photoanode modified with cobalt-phosphate-loaded TiO2 nanoparticles

Because the oxygen evolution reaction (OER) involves a complicated four-electron process, reducing the overpotential for the OER by loading cocatalysts at as high a concentration as possible is critical for achieving efficient photoelectrochemical (PEC) water oxidation. However, such surface modifications should also be designed to not interfere with the bandgap photoexcitation of the light-absorbing materials. In the present study, cobalt-phosphate-loaded TiO2 (CoPi/TiO2) nanoparticles were used to modify a particulate BaTaO2N (BTON) photoanode, resulting in an improvement in the photoanode PEC OER performance. The TiO2 nanoparticles functioned as a transparent and conductive support with a high specific surface area to immobilize CoPi on the photoanode surface. Electrochemical measurements revealed that the CoPi/TiO2 modification led to improved reaction kinetics and that the electrochemically active surface area of the CoPi cocatalysts deposited on the electrode surface substantially increased by a factor of 7.45 as a result of the TiO2 modification. The CoPi/TiO2 modification increased the number of active sites on the surface of the particulate BTON photoanode and minimized the harmful influence of light shielding, thereby accelerating the OER kinetics. Published under an exclusive license by AIP Publishing.