Deposition of zinc cobaltite nanoparticles onto bismuth vanadate for enhanced photoelectrochemical water splitting.

During the past few decades, photoelectrochemical (PEC) water splitting has attracted significant attention because of the reduced production cost of hydrogen obtained by utilizing solar energy. Significant efforts have been invested by the scientific community to produce stable ternary metal oxide semiconductors, which can enhance the stability and increase the overall production of oxygen. Herein, we present the ternary metal oxide deposition of ZnCoO as a route to obtain a novel photocatalyst layer on BiVO to form BiVO/ZnCoO a novel composite photoanode for PEC water splitting. The structural, topographical, and optical analyses were performed using field emission scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy, and UV-Vis spectroscopy to confirm the structure of the ZnCoO grafted over BiVO. A remarkable 4.4-fold enhancement of the photocurrent was observed for the BiVO/ZnCoO composite compared with bare BiVO under visible illumination. The optimum loading of ZnCoO over BiVO yields unprecedented stable photocurrent density with an apparent cathodic shift of 0.46 V under 1.5 AM simulated light illumination. This is also evidenced by the flat-band potential change through Mott-Schottky analysis, which reveals the formation of p-ZnCoO on n-BiVO. The improvement in the PEC performance of the composite with respect to bare BiVO is ascribed to the formation of thin passivating layer of p-ZnCoO on n-BiVO which improves the kinetics of interfacial charge transfer. Based on our study, we have gained an in-depth understanding of the BiVO/ZnCoO composite as high potential in efficient PEC water splitting devices.