Molten Salt Synthesis of Mg-Doped Ta3N5 Nanoparticles with Optimized Surface Properties for Enhanced Photocatalytic Hydrogen Evolution

Tantalum nitride (Ta3N5) with a narrow band gap (2.1 eV) is a promising material for photocatalytic water splitting using visible light. However, charge separation/transfer is the main factor limiting the photocatalytic performance. Herein, Ta3N5 nanorods with uniform diameter of ∼40 nm for fast separation and transfer of photogenerated charges were developed by nitridation of metallic Ta nanoparticles through a molten salt process. The charge carrier separation efficiency of Ta3N5 is enhanced by doping of Mg cations, and the obtained Ta3N5:Mg(1.0 wt %) nanorods have uniform morphology with optimized surface properties, thereby displaying enhanced photocatalytic activity. The key factors associated with Mg doping and cocatalyst loading that provided the enhanced activity included surface wettability, surface charge property, defects, and close contact between cocatalyst and photocatalyst and were studied in detail. This work provides a one-step strategy to prepare Ta3N5 nanorods with optimized surface properties and is beneficial to the understanding and improvement of Ta3N5-based photocatalysts.