Enhanced Photoelectrochemical Activity of Anodically Generated FTO/Nanoporous SnOx Decorated with BiVO₄

In this work, we report a comprehensive study on the fabrication of nanoporous tin oxide layers via anodic oxidation of Sn with different thicknesses sputtered on an fluorine doped tin oxide (FTO) glass substrate. A special emphasis was put on the relation between morphological features of the SnOx layers with their photoelectrochemical properties in the water splitting performance. Afterwards, tin oxide films were subjected to sensitization with BiVO4, and all of the as-obtained heterostructures underwent a complex characterization of morphology and chemical composition, together with optical and photoelectrochemical properties. Performed tests confirmed a significant improvement of the photoresponse in the ultraviolet–visible (UV–Vis) range resulting from the BiVO4 addition, and the enhancement was found to be strictly dependent on the morphology of SnOx layers. Moreover, we also evaluated the benefits of using SnOx within its nanoporous form in such heterostructures by comparing nanoporous tin oxide layers with the behavior of SnOx films obtained directly by thermal oxidation of metallic Sn. During the work, we proved that the morphological features of tin oxide play a key role in the design of electrodes for efficient photoelectrochemical water splitting devices.