Phase Transformation Synthesis of Strontium Tantalum Oxynitride-Based Heterojunction for Improved Visible Light-Driven Hydrogen Evolution

Tantalum oxynitride-based materials, which possess narrow band gaps and sufficient band energy potentials, have been of immense interest for water splitting. However, the efficiency of photocatalytic reactions is still low because of the fast electron–hole recombination. Here, a Sr2Ta2O7–xNx/SrTaO2N heterostructured photocatalyst with a well-matched band structure was in situ constructed by the nitridation of hydrothermal-prepared Sr2Ta2O7 nanosheets. Compared to Sr2Ta2O7–xNx and pure SrTaO2N, the Sr2Ta2O7–xNx/SrTaO2N heterostructured photocatalyst exhibited the highest rate of hydrogen evolution, which is ca. 2.0 and 76.4 times of Sr2Ta2O7–xNx and pure SrTaO2N, respectively, under the similar reaction condition. The enhanced performance arises from the formation of suitable band-matched heterojunction-accelerated charge separation. This work provides a promising strategy for the construction of tantalum oxynitride-based heterojunction photocatalysts.