Template-free synthesis of honeycomb-structured Ta3N5 foam nanoplates with expanded light absorption, abundant active sites and fast charges transport for visible-light-driven H2 evolution†

Tantalum nitride (Ta₃N₅) with suitable band structure and high theoretical solar-to-hydrogen energy conversion efficiency (15.9%) is regarded as one of the most promising semiconductor-based photocatalysts for hydrogen evolution via water splitting. However, it is practically constrained by the slow carrier mobility, fast electron–hole recombination and unabundant catalytic active sites. Herein, honeycomb-structured Ta₃N₅ foam nanoplates were successfully synthesized using a simple template-free strategy. It can not only capture broader visible light to generate the high concentration of photo-generated carriers, but also accelerate the rapid transport/separation of carriers and provide abundant active sites to accelerate the kinetics of water splitting reaction. Therefore, honeycomb-structured Ta₃N₅ exhibits excellent photocatalytic performance with a remarkably enhanced H₂ production rate of 59.16 μmol h⁻¹ g⁻¹, which is 22.7 times higher than that of the conventional bulk Ta₃N₅. Moreover, the unique Ta₃N₅ with honeycomb structure has outstanding stability and recycling ability. This work provides a simple and effective strategy for the preparation of Ta₃N₅-based photocatalysts for efficient and stable H₂ production.