Molten-salt defect engineering of TiO2(B) nanobelts for enhanced photocatalytic hydrogen evolution

Abstract

Defect engineering has been proved to be an effective strategy to adjust the electronic structures and photocatalytic activities of semiconductor oxides. However, due to lack of convenient approach to construct defect, the effect of oxygen vacancy defect on photocatalytic hydrogen evolution has always been controversial. Herein, we proposed a facile molten-salt defect engineering (MSDE) strategy to introduce oxygen vacancies (Vos) defects in TiO₂(B) nanobelt (TNB). By tuning the addition amount of NaBH₄ during molten-salt calcination process, the concentration of surface oxygen vacancies can be effectively adjusted. As a result, the appropriate oxygen vacancies on TNB not only suppressed the recombination of photogenerated electrons and holes, but also raised the conduction band position of TNB, thereby increasing the reduction potential of photogenerated electrons. The as-prepared photocatalyst TNB-NaBH₄-2 with optimal Vos concentration exhibited highly efficient photocatalytic hydrogen evolution performance at a rate of 3.2 ​mmol ​g⁻¹h⁻¹ under simulate solar light, nearly 1.85 times than that of pristine TNB. This work proposes a simple method for constructing moderate oxygen vacancies on metal oxides for enhancing photocatalytic hydrogen evolution.