Hydrogen plasma reduction induced oxygen vacancies in cubic In2O3 particles with enhanced photocatalytic performance

The impacts of oxygen vacancies on the photocatalytic performance of In2O3 particles were never investigated previously. In this paper, cubic shape In2O3 particles were synthesized by hydrothermal method, and different concentrations of oxygen vacancies were generated in In2O3 particles by controlling the H2 gas flow rate in hydrogen plasma reduction. The SEM images confirmed that the hydrogen plasma reduction did not change the particle morphology. The existence of oxygen vacancies was determined by electron paramagnetic resonance spectrum. Finally, the photocatalytic performance of In2O3 particles with different concentration of oxygen vacancies was investigated by the degradation of Methylene Blue (MB) solution under visible light irradiation. It was observed that when the hydrogen flow rate is 2 mL/min, the sample showed the highest photocatalytic performance, a further increased flow rate resulted in a decreased photocatalytic performance, which could be attributed to the over reduction of In2O3.