Constructing Rh–Rh(3+) modified Ta(2)O(5)@TaON@Ta(3)N(5) with special double n–n mutant heterojunctions for enhanced photocatalytic H(2)-evolution

A multiple core–shell heterostructure Rh–Rh(3+) modified Ta(2)O(5)@TaON@Ta(3)N(5) nanophotocatalyst was successfully constructed through nitriding Rh(3+)-doped Ta(2)O(5) nanoparticles, which exhibited a much higher carrier separation efficiency about one order of magnitude higher than the Ta(2)O(5)@Ta(3)N(5) precursor, and thus an excellent visible light photocatalytic H(2)-evolution activity (83.64 μmol g(−1) h(−1)), much superior to that of Rh anchored Ta(2)O(5)@TaON (39.41 μmol g(−1) h(−1)), and improved stability due to the residual Rh–O/N in the Ta(3)N(5) shell layer. Rh-modifying significantly extended light absorption to the overall visible region. Localized built-in electric fields with hierarchical potential gradients at the multiple interfaces including a Rh/Ta(3)N(5) Schottky junction and double n–n Ta(3)N(5)/TaON/Ta(2)O(5) mutant heterojunctions, drove charge carriers to directionally transfer from inside to outside, and efficiently separate. Enhanced photoactivity was ascribed to a synergetic effect of improved light absorption ability, increased carrier separation efficiency, and accelerated surface reaction. A promising strategy of developing excellent Ta(3)N(5)-based photocatalysts for solar energy conversion is provided by constructing double n–n mutant heterojunctions.