Improving photoelectrochemical performance of SnO2 nanocones through TiOx shell via atomic layer deposition

Abstract

Amorphous titanium oxide (TiOx) has recently garnered significant attention due to its disorder-mediated optical and electrical properties, in contrast to the crystalline TiO2 polymorphs. This research presents a novel approach for preparing SnO2/TiOx heterostructures. Ultrathin amorphous TiOx coatings of varying thicknesses, realized by Atomic Layer Deposition (ALD) on SnO2 nanocones, were used to investigate their impact on photo- electrochemical properties of resulting SnO2/TiOx heterostructures, as well as to enhance chemical and electrochemical stability of SnO2 itself. Uncoated SnO2 nanocones were utilized as reference materials for comparative assessment. SnO2 nanocones were prepared through a modified low-temperature Chemical Vapor Deposition (CVD) method, followed by an application of TiOx shell using an optimized ALD process. Morphological and chemical characterization of the SnO2/TiOx core-shell heterostructure was conducted using field emission electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The light absorption ability was evaluated using UV-Vis spectroscopy, and the photoelectrochemical properties were assessed using monochromatic light and a solar light simulator. The impact of TiOx shell thickness on photoelectrochemical properties was meticulously assessed and correlated with changes in charge carrier kinetics, providing an understanding of how variations in TiOx shell dimensions affect photoelectrochemical properties in SnO2/TiOx photoanodes.