Self-trapped holes, oxygen vacancies and electrocatalytic performance of Zn-doped β-Ga2O3 microspindles

Gallium oxide (beta-Ga2O3) is a well-known extra-wide bandgap semiconductor and one of the promising materials used for power photoelectric devices, gas sensors, catalytic agents, etc. This work presents the suppression of self-trapped holes (STHs) and increase of oxygen vacancies (V-O) in beta-Ga2O3 microspindles by doping of Zn ions as well as the electrocatalytic activity of these microspindles. Undoped and Zn-doped beta-Ga2O3 microspindles were prepared by a hydrothermal method followed by high-temperature calcination. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results show that the morphology and structure of the samples did not change after low dose of Zn doping. The analyses of temperature-dependent photoluminescence (PL) spectra and X-ray photoelectron spectroscopy (XPS) indicate that incorporation of divalent Zn ions as deep acceptors can increase V-O concentration and effectively suppress the formation of STHs. Enhanced electrocatalytic activity was observed in Zn-doped beta-Ga2O3 microspindles compared with undoped beta-Ga2O3 microspindles. The new active sites introduced by Zn doping, higher V-O concentration, and suppressed STHs are believed to be responsible for the enhanced electrocatalytic performance of Zn-doped beta-Ga2O3 microspindles. This work is expected to expand the application of beta-Ga2O3 based microstructures in electrocatalysis and provide innovative ideas for energy and environmental issues.