Investigation into the synthesis conditions of CuMoO(4) by an in situ method and its photocatalytic properties under visible light irradiation

A kind of molybdenum and copper compound, CuMoO(4), was prepared by a hydrothermal method. The construction and photocatalytic properties of CuMoO(4) have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, transmission electron microscopy (TEM), UV-visible spectrometry and comprehensive thermal analysis. XRD analysis showed that samples which were synthesized under different hydrothermal time conditions were consistent, but the crystallinities of the samples were different. In another situation, disparate hydrothermal temperatures during the synthesis of CuMoO(4) would lead to the appearance of different samples. The band gap of CuMoO(4) was estimated to be 1.97 eV. It could be found from the results that CuMoO(4) was an indirect band gap semiconductor by simulating its band structure. The photocatalytic activities of CuMoO(4) were studied by means of monitoring the abilities of these compounds to degrade rhodamine B or 1H-benzotriazole in liquid media under visible light irradiation. Under different synthesis conditions, the hydrothermal time for obtaining the optimal degradation efficiency was 10 h, and the hydrothermal temperature was 180 °C. The results showed that CuMoO(4) had excellent degradation performance for rhodamine B or 1H-benzotriazole. CuMoO(4) showed excellent mineralization efficiency for rhodamine B compared with N-doped TiO(2) based on the reduction of total organic carbon (TOC) during the photocatalytic process. The photocatalytic degradation rate of rhodamine B by CuMoO(4) was 1.39 times that by N-doped TiO(2), and the degradation rate of TOC by CuMoO(4) was 1.53 times that by N-doped TiO(2). Based on the intermediate products which were detected by liquid chromatography/mass spectrometry (LC/MS), the possible degradation pathway of rhodamine B was derived.