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

NaNb x Ta 1-x O 3 , 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. NaNb 0.33 Ta 0.67 O 3 exhibits the best performance with produced H 2 of 1038 μmol g−1 in 5 h, which is more than 5 times than NaTaO 3 and NaNbO 3. It is also close to 5 times and 2 times than NaTaO 3 /Pt and NaNbO 3 /Pt, respectively. NaNb 0.33 Ta 0.67 O 3 has a transition state crystal structure between NaTaO 3 and NaNbO 3 crystalline phase. Moreover, XPS, ESR and TEM characterizations demonstrates that there are abundant oxygen vacancies in NaNb 0.33 Ta 0.67 O 3. 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. [Display omitted] • NaNb x Ta 1-x O 3 photocatalysts were prepared by a facile hydrothermal method. • NaNb x Ta 1-x O 3 had superior photocatalytic H 2 evolution ability without co-catalyst. • The maximum yield of H 2 was 1038 μmol. g−1 over NaNb 0.33 Ta 0.67 O 3 in 5 h. • Produced H 2 over NaNb 0.33 Ta 0.67 O 3 was more than 5 times than NaTaO 3 and NaNbO 3. • Excellent performance depended on transition state structure and oxygen vacancy. [ABSTRACT FROM AUTHOR]