Preparation of Ta 3 N 5 Nanosheet by Nitridation of Monolayer Tantalum Oxide Nanosheet

Two‐dimensional semiconducting materials have attracted attention as photocatalysts, electrode catalysts and electronic materials. However, preparation of metal nitride nanosheet is still a significant challenge. Here, we show a tantalum nitride (Ta 3 N 5 ) nanosheet with a thickness of 1.5 nm prepared via tantalum oxide [TaO 3 ] − nanosheet derived from layered rubisium tantalum oxide (RbTaO 3 ). The monolayer tantalum oxide nanosheet was converted to Ta 3 N 5 nanosheet with a [110] preferred orientation in the in‐plane direction during annealing under NH 3 gas flow, and showed a photocatalytic activity for H 2 evolution under visible light illumination (550 nm). The H 2 evolution ratio of the ultrathin Ta 3 N 5 nanosheet was much higher than that of bulk Ta 3 N 5 prepared from Ta 2 O 5 powder, indicating that nanosheet structure suppresses the recombination in the photocatalytic reaction.