Novel Heterostructure\nas a H<sub>2</sub>‑Evolving\nPhotocatalyst Boosting the Z‑Scheme Overall Water Splitting\nPerformance under Visible Light Irradiation

Tantalum nitride (Ta<sub>3</sub>N<sub>5</sub>) has been\nwidely\ninvestigated as an extremely promising photocatalyst or photoanode\nfor solar water splitting, but its performance is blocked by inefficient\ncharge separation regardless of using a one-step or two-step excitation\nmethod. Here, we demonstrate significantly enhanced proton reduction\non the particulate Ta<sub>3</sub>N<sub>5</sub> photocatalyst with\nan effort for the promotion of charge separation via forming a solid\nsolution-based heterostructure composite. One-pot nitridation was\nadopted to synthesize this novel heterostructure, which is composed\nof Ta<sub>3</sub>N<sub>5</sub> and BaZrO<sub>3</sub>–BaTaO<sub>2</sub>N solid solution. The as-obtained composite (BaZrO<sub>3</sub>–BaTaO<sub>2</sub>N/Ta<sub>3</sub>N<sub>5</sub>) is found\nto exhibit superior charge separation and transfer ability compared\nwith Ta<sub>3</sub>N<sub>5</sub> and BaZrO<sub>3</sub>–BaTaO<sub>2</sub>N. As a result, the visible-light-driven Z-scheme overall\nwater splitting (OWS) activity using the optimal BaZrO<sub>3</sub>–BaTaO<sub>2</sub>N/Ta<sub>3</sub>N<sub>5</sub> composite\nas the H<sub>2</sub>-evolving photocatalyst can be promoted by about\n20 times. This work not only gives the first example to fabricate\nheterostructures based on solid solution for enhanced charge separation\nbut also offers a new avenue to improve the photocatalytic OWS performance\nof Ta<sub>3</sub>N<sub>5</sub>.