A wide visible light driven complex perovskite Ba(Mg1/3Ta2/3)O3−xNy photocatalyst for water oxidation and reduction

Abstract

The development of potential photocatalysts that can harvest visible light and drive the two half reactions of water splitting is of vital importance in solar energy utilization. Here we report a new deep nitrogen-doped complex perovskite metal oxide Ba(Mg_1/3Ta_2/3)O_3−xN_y (denoted as BMTON) that shows a wide visible light response with an absorption edge of ca. 560 nm rather than a shoulder absorption. Various characterizations indicate that the greatly extended light absorption is mainly ascribed to the efficient nitrogen doping into the oxide precursor Ba(Mg_1/3Ta_2/3)O₃ (denoted as BMTO) that can be simply understood as lattice Mg partly substituted BaTaO_x. Meanwhile, theoretical results demonstrate that the weakened Ta–O bonds of the oxide precursor by the substitution of Mg atoms with lower electronegativity than Ta atoms are responsible for the enhanced nitrogen permeation. After loading of cocatalysts Pt or CoO_x, BMTON is active for H₂ and O₂ evolution under visible light irradiation in the presence of CH₃OH and AgNO₃, respectively. This work may open a new avenue to prepare nitrogen-doped metal oxides with wide visible light utilization for potential solar energy conversion by choosing suitable precursor oxides for nitridation.