Stable Co-Catalyst-Free Photocatalytic H2 Evolution from Oxidized Titanium Nitride Nanopowders

Abstract

A simple strategy is used to thermally oxidize TiN nanopowder (∼20nm) to an anatase phase of a TiO2:Ti3+:N compound. In contrast to the rutile phase of such a compound, this photocatalyst provides activity for hydrogen evolution under AM1.5 conditions, without the use of any noble metal co-catalyst. Moreover the photocatalyst is active and stable over extended periods of time (tested for 4months). Importantly, to achieve successful conversion to the active anatase polymorph, sufficiently small starting particles of TiN are needed. The key factor for catalysis is the stabilization of the co-catalytically active Ti3+ species against oxidation by nitrogen present in the starting material. Thermal oxidization of TiN nanopowder can lead to an anatase phase of a photocatalyst capable of hydrogen evolution. The photocatalyst provides activity for hydrogen evolution under AM1.5 conditions, without the use of a noble metal co-catalyst, and is stable over extended periods of time.