Preparation of (Zn1+xGe)(N2Ox) nanoparticles with enhanced NOx decomposition activity under visible light irradiation by nitridation of Zn2GeO4 nanoparticles designed precisely

Abstract

Quaternary zinc germanium oxynitride (Zn_1+xGe)(N₂O_x), a solid solution between ZnGeN₂ and ZnO with a wurtzite structure, is one of the attractive photocatalysts under visible-light irradiation. In this study, the synthesis of (Zn_1+xGe)(N₂O_x) nanoparticles was achieved by the nitridation of Zn₂GeO₄ nanoparticles designed precisely to enhance their photocatalytic NO_x decomposition activity under both UV and visible light irradiation. The obtained (Zn_1+xGe)(N₂O_x) nanoparticles exhibited a high specific surface area and visible light absorption induced by the narrow band gap of ca. 2.6–2.8 eV, both of which are reasons for the enhancement of photocatalytic activity. The oxide precursors with a nanoparticle morphology were prepared by a facile solvothermal method with various volumes of TEA (triethanolamine) as an additive. The relationships of nitridation time and TEA volume in the solvothermal reaction for the synthesis of the precursor with morphology, specific surface area, and photocatalytic NO_x decomposition activity of the nitrided samples were investigated. The increase of active sites by the high surface area and the enhanced visible-light absorption ability as well as the defect amounts and states can be largely related to the excellent NO_x decomposition activity of (Zn_1+xGe)(N₂O_x).