Stable Formation of BiVO4/ZnO Heterostructure via a Soft Deposition Method

Abstract

This work presents the results of a mild two-step layer-by-layer deposition of bismuth vanadate (BiVO₄) onto hydrothermally synthesized zinc oxide (ZnO) nanorods using the spin-coating method. Controlling the viscosity and precursor concentration plays a key role in tuning the thickness, uniformity, and stability of the BiVO₄ films formed on ZnO. The synthesized samples were characterized using a range of analytical techniques. First, UV–Vis spectroscopy was used to determine the absorption spectrum in the visible range after BiVO₄ deposition. Next, X-ray diffraction (XRD) confirmed the presence of the monoclinic phase of BiVO₄ and the wurtzite phase of ZnO, as well as the degree of crystallinity of the samples. Finally, scanning electron microscopy (SEM) revealed the morphology of ZnO nanorods and the stable coating of their surface with a BiVO₄ layer. To evaluate the practical performance of the BiVO₄/ZnO heterostructures, photoelectrochemical (PEC) measurements were conducted under natural outdoor conditions using linear sweep voltammetry, demonstrating the operability of the films in real environments. The obtained results confirm that the proposed two-step spin-coating method with optimized solution viscosity enables the formation of stable heterostructures suitable for use in photoelectrochemical devices.