Improving Photoelectrochemical Performance of SnO2 Nanocones Through TiOx Shell via Atomic Layer Deposition

Abstract

Amorphous titanium oxide (TiO_x) 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/TiO_x heterostructures. Ultrathin amorphous TiO_x coatings of varying thicknesses, realized by Atomic Layer Deposition (ALD) on SnO₂ nanocones, were used to investigate their impact on photoelectrochemical properties of resulting SnO₂/TiO_x 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 TiO_x shell using an optimized ALD process. Morphological and chemical characterization of the SnO₂/TiO_x 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 TiO_x shell thickness on photoelectrochemical properties was meticulously assessed and correlated with changes in charge carrier kinetics, providing an understanding of how variations in TiO_x shell dimensions affect photoelectrochemical properties in SnO₂/TiO_x photoanodes.