Visible-Light Harvesting SrTiO₃ Solid Solutions for Photocatalytic Hydrogen Evolution from Water

The fabrication of solid solutions represents a compelling approach to modulating the physicochemical properties of materials. In this study, we achieved the successful synthesis of solid solutions comprising SrTiO₃ and SrTaO₂N (denoted as (SrTiO₃)_1-x-(SrTaO₂N)_x, 0≤x≤1) using the magnesium powder-assisted nitridation method. The absorption edge of (SrTiO₃)_1-x-(SrTaO₂N)_x is tunable from 500 to 600 nm. The conduction band minimum (CBM) of (SrTiO₃)_1-x-(SrTaO₂N)_x comprises the Ti 3d orbitals and the Ta 5d orbitals, while the valence band maximum (VBM) consists of the O 2p and N 2p orbitals. The microstructure of the (SrTiO₃)_1-x-(SrTaO₂N)_x consists of small nanoparticles, exhibiting a larger specific surface area than the parent compounds of SrTiO₃ and SrTaO₂N. In the photocatalytic hydrogen evolution reaction (HER) with sacrificial reagents, the activity of solid solutions is notably superior to that of nitrogen-doped SrTiO₃ and SrTaO₂N. This superiority is mainly attributed to its broad light absorption range and high charge separation efficiency, which indicates its potential as a promising photocatalytic material. Moreover, the magnesium powder-assisted nitridation method exhibits obvious advantages for the synthesis of oxynitrides and bears instructional significance for the synthesis of other nitrogen-containing compounds and even sulfur-containing compounds.