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

Gallium oxide (β-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 (VO) in β-Ga2O3 microspindles by doping of Zn ions as well as the electrocatalytic activity of these microspindles. Undoped and Zn-doped β-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 VO concentration and effectively suppress the formation of STHs. Enhanced electrocatalytic activity was observed in Zn-doped β-Ga2O3 microspindles compared with undoped β-Ga2O3 microspindles. The new active sites introduced by Zn doping, higher VO concentration, and suppressed STHs are believed to be responsible for the enhanced electrocatalytic performance of Zn-doped β-Ga2O3 microspindles. This work is expected to expand the application of β-Ga2O3 based microstructures in electrocatalysis and provide innovative ideas for energy and environmental issues.