Advancing bandgap tuning: Novel nitrogen doping in KLaTiO4 with uncompromised crystallinity

Abstract

KLaTiO4 is a promising photocatalyst, producing 9.54(11) µmol of hydrogen gas per hour. Its high bandgap, of 4.09 eV, makes it unsuitable for direct photocatalysis under sunlight irradiation. In this study two novel methods of doping KLaTiO4 with nitrogen were studied, in an attempt to reduce the bandgap of KLaTiO4 without inducing structural degradation of the photocatalyst, which adversely affects the hydrogen evolution rate. The first method involves post-synthesis calcination of KLaTiO4 with urea under a nitrogen atmosphere, and the second method attempts to introduce nitrogen during synthesis, by replacing TiO2 with TiN as a starting reagent. The samples were structurally characterised using powder X-ray diffraction and their bandgap and photocatalytic performance determined by Tauc plot and hydrogen evolution testing. Density Function Theory calculations have been used to probe the likely site of nitrogen doping.