Enhanced Photocatalytic Activity of SrMoO 4 via SrMo(O, N) 3 Formation by Annealing in NH 3 Atmosphere

Via the hydrothermal method, one nitrogen-doped molybdate SrMoO 4 photocatalyst was synthesized. In the synthesization process, further nitrogenization technique under a high-temperature NH 3 atmosphere at different temperatures was also adopted. The obtained samples were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and UV-Visible absorption spectroscopy. The XRD and XPS results suggest that the SrMo(O,N) 3 phase appears with the sintering temperature being 500°C. The absorption edge of SrMoO 4 material is red-shifted to the visible part of the spectrum with N-doping, and then visible light photocatalytic activity is enabled. When the nitridtion temperature is up to 900°C, the photocatalytic degradation efficiency of methyl blue is increased up to 98% in 140 min. The excellent photocatalytic performance is ascribed to the following two factors induced by N doping. One is the formation of one phase SrMo(O,N) 3 , and the other is the formation of one heterojunction between SrMo(O,N) 4 and SrMo(O,N) 3 . The heterojunction efficiently separates the photogenerated charge carriers and eventually reduces the recombination of the photogenerated electron-hole pairs. Moreover, one possible degradation pathway and the corresponding photocatalytic mechanism are both discussed.