LaTiO2N–LaCrO3: continuous solid solutions towards enhanced photocatalytic H2 evolution under visible-light irradiation

Abstract

(LaTiO₂N)_1−x(LaCrO₃)_x continuous solid solutions with an orthorhombic-phase ABX₃ perovskite structure and with varied LaCrO₃ contents (0 ≤ x ≤ 1) were synthesized by a polymerized complex method followed by a post-treatment process of nitridation for the first time. Visible-light-driven photocatalytic H₂-evolution activities of the solid solutions gradually increased with the increase of x from 0.0 to 0.3, and then sharply decreased with the further increase of x from 0.3 to 1.0. With the increase of x, on the one hand, the narrowed bandgaps of solid solutions would enhance the generation of charge carriers and the increased lattice distortion of solid solutions could promote the separation and migration of charge carriers, thus mainly contributing to the improvement of photocatalytic activities; on the other hand, the lowered CBMs of solid solutions would reduce the driving force for reducing H₂O to H₂ and the decreased surface areas of solid solutions would weaken the adsorption of reactants and reduce the reactive sites, thereby resulting in the deterioration of photocatalytic activities.