Aluminum-doped mesoporous single-crystalline SrTaO2N for boosted photocatalytic hydrogen production

SrTaO 2 N is an attractive photocatalyst for solar water splitting due to its wide visible light absorption and suitable conduction/valence band position. The formation of porous single crystals is beneficial for the migration of photogenerated carriers from the bulk to the surface. However, the photocatalytic activity is still severely hindered by its intrinsic defects generated during the synthesis process. In this work, Al is selected as the dopant to replace part of Ta sublattice without changing the mesoporous single-crystal characteristics of SrTaO 2 N, in order to address the limitation by reducing the concentration of (such as Ta 4+ ). Based on the above findings, the charge separation is promoted, thereby enhancing photocatalytic proton reduction under visible light illumination. Under optimal conditions, the Al-doped SrTaO 2 N exhibits a stable H 2 evolution rate, which is seven times higher performance than that of SrTaO 2 N, so as to the activity increase of photocatalytic Z-scheme overall water splitting when using them as the H 2 -evloving photocatalyst. Besides, theoretical calculations indicated that the smaller Gibbs free energy and stronger catalyst-methanol interaction caused by Al doping compared with pristine SrTaO 2 N are the main reasons for the improved photocatalytic hydrogen production performance. These results verify that Al is an effective dopant for modifying the photocatalytic potential of Ta-based oxynitrides.