Facile synthesis of NaNbxTa1-xO3 with abundant oxygen vacancies for photocatalytic hydrogen evolution without co-catalyst

Abstract

NaNbxTa1-xO3, sodium tantalate and niobate with B atoms substitution is synthesized by a facile one-step hydrothermal method. They are effective photocatalysts for hydrogen evolution from water splitting without co-catalyst. NaNb0.33Ta0.67O3 exhibits the best performance with produced H2 of 1038 μmol g−1 in 5 h, which is more than 5 times than NaTaO3 and NaNbO3. It is also close to 5 times and 2 times than NaTaO3/Pt and NaNbO3/Pt, respectively. NaNb0.33Ta0.67O3 has a transition state crystal structure between NaTaO3 and NaNbO3 crystalline phase. Moreover, XPS, ESR and TEM characterizations demonstrates that there are abundant oxygen vacancies in NaNb0.33Ta0.67O3. These features give the catalyst excellent properties, such as good light harvesting and efficient charge separation confirmed by optical and electrochemical characterizations. This work may offer a strategy to develop perovskite sodium tantalate and niobate with controllable crystal structure and oxygen vacancies for highly efficient photocatalytic hydrogen evolution in the absence of co-catalyst.