Amorphous CoB layer cooperates with piezoelectric polarization to boost carrier separation of Bi2WO6 for efficient piezo-PEC performance

Abstract

Poor surface charge reaction efficiency and conductivity limit the further application of Bi₂WO₆ in piezoelectric photocatalytic water splitting. Amorphous cobalt–boron (CoB) layers were deposited on bismuth tungstate nanoplates by photo-assisted electrodeposition. The presence of an amorphous CoB layer accelerates the charge transport and water oxidation kinetics, resulting in a greatly enhanced photocurrent with the reversible hydrogen electrode, with a photocurrent density of about 0.288 mA cm⁻² at 1.23 V vs. RHE, more than three times that of the pure Bi₂WO₆ photoelectrode. Under ultrasonic conditions, the photocurrent of Bi₂WO₆/CoB-2 is further increased to 0.382 mA cm⁻², which is almost 3.5 times that of pure Bi₂WO₆ under the same conditions. The detailed experimental data show that the amorphous cobalt–boron layer not only effectively reduces the hole accumulation on the surface of the photoelectrode and improves the piezoelectric photoelectrocatalytic stability of the photoelectrode but can also effectively accelerate charge interface transfer under piezoelectric polarization, thus effectively improving the photocarrier separation efficiency. This study presents a novel strategy for further practical application of Bi₂WO₆ photoelectrode piezoelectric photocatalysis.