Preparation of Ta3N5 Nanosheet by Nitridation of Monolayer Tantalum Oxide Nanosheet

Abstract 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.