Novel Heterostructure as a H₂-Evolving Photocatalyst Boosting the Z-Scheme Overall Water Splitting Performance under Visible Light Irradiation

Tantalum nitride (Ta3N5) has been widely investigated as an extremely promising photocatalyst or photoanode for solar water splitting, but its performance is blocked by inefficient charge separation regardless of using a one-step or two-step excitation method. Here, we demonstrate significantly enhanced proton reduction on the particulate Ta3N5 photocatalyst with an effort for the promotion of charge separation via forming a solid solution-based heterostructure composite. One-pot nitridation was adopted to synthesize this novel heterostructure, which is composed of Ta3N5 and BaZrO3–BaTaO2N solid solution. The as-obtained composite (BaZrO3–BaTaO2N/Ta3N5) is found to exhibit superior charge separation and transfer ability compared with Ta3N5 and BaZrO3–BaTaO2N. As a result, the visible-light-driven Z-scheme overall water splitting (OWS) activity using the optimal BaZrO3–BaTaO2N/Ta3N5 composite as the H2-evolving photocatalyst can be promoted by about 20 times. This work not only gives the first example to fabricate heterostructures based on solid solution for enhanced charge separation but also offers a new avenue to improve the photocatalytic OWS performance of Ta3N5.