Continuous solid solutions of Na_0.5La_0.5TiO₃-LaCrO₃ for photocatalytic H₂ evolution under visible-light irradiation

A series of continuous (Na_0.5La_0.5TiO₃)_1-x(LaCrO₃)_x solid solutions with orthorhombic-phase perovskite structure and with LaCrO₃ contents (x) in the range from 0 to 1.0 were synthesized by a facile polymerized complex method, and were employed as photocatalysts for H₂ evolution under visible-light irradiation. It was found that photocatalytic activities of the solid solutions significantly increased with the increase of x to 0.3, and reached the highest H₂-evolution rate of 238.2 μmol h^-1 g_cat^-1 on (Na_0.5La_0.5TiO₃)_0.7(LaCrO₃)_0.3, because the narrowed bandgaps of samples enhanced the generation of charge carriers and the increased lattice distortion of samples could promote the separation and migration of charge carriers. Nevertheless, photocatalytic activities of the solid solutions gradually decreased with the further increase of x from 0.3, since both the bandgaps and lattice distortion rarely changed but Cr⁶⁺ and defects gradually increased and thus accelerated the recombination of charge carriers.