Layered oxide precursor strategy for the synthesizing of titanium oxynitrides

Abstract

Oxynitride is a mixture of mixed oxide and nitride anions. The creation of simple synthesis methods remains a challenge. Herein, we propose a synthetic method that uses the layered oxide Cs0.68Ti1.83O4 precursor to directly create oxynitride Ti2.85O4N without the need for ammonia. Using a topochemical reaction at 500 °C, a combination of solid Cs2CO3 and TiO2 was converted into the layered oxynitride Cs0.68+xTi1.83O4-xNx.‬‬‬‬‬‬ The crystal structure of Ti2.85O4N has been analyzed by Rietveld refinement with synchrotron radiation data. The UV–Vis spectra revealed that Ti2.85O4N has an absorption edge around 650 nm. Ti2.85O4N exhibits photocatalytic activity for hydrogen evolution utilizing methanol as a reversible electron donor in the visible range (λ > 420 nm) when promoted by platinum. In contrast, the intermediate oxynitride Cs0.68+xTi1.83O4−xNx with surface NHx species does not exhibit photocatalytic activity. These findings open new opportunities for novel titanium oxynitrides photocatalysts.‬‬‬‬‬‬‬