Improving the Efficiency of Gallium Telluride for Photocatalysis, Electrocatalysis, and Chemical Sensing through Defects Engineering and Interfacing with its Native Oxide

摘要

Gallium telluride (GaTe) is a van der Waals semiconductor, currently adoptedfor photonic and optoelectronic devices. However, the rapid degradation ofGaTe in air, promoted by Te vacancies, is detrimental for device applications.Here, it is demonstrate that the surface oxidation of GaTe can be unexpectedlyexploited for expanding the breadth of applications of GaTe. Specifically,the formation of a nanoscale sub-stoichiometric wide-band-gap Ga_2O_3 skin,promoted by Te vacancies, over narrow-band-gap GaTe_x upon air exposure isbeneficial for electrocatalysis, photocatalysis, and gas sensing . In particular,the Heyrovsky step (H_(ads) + H~+ + e~? → H_2) of hydrogen evolution reaction inan acidic medium is barrier-free for the sub-stoichiometric gallium-oxide/gallium-telluride heterostructure, which also enables a significant reductionof costs with respect to state-of-the-art Pt/C electrodes. In the photocatalyticprocess, the photo-generated electrons migrate from GaTe to Ga2O_x skin,which acts as the chemically active side of the interface. Moreover, the Ga_2O_3/GaTe heterostructure is a suitable platform for sensing of H_2O, NH_3, and NO_2at operational temperatures extended up to 600 ℃ (useful for gas detection incombustion processes), mainly due to the increased area of charge redistributionafter adsorption achieved upon oxidation of GaTe.