A novel octamolybdate‐based organic–inorganic hybrid as photo‐Fenton‐like catalyst for degradation of methylene blue

Abstract

A γ‐Mo8O26‐based organic–inorganic hybrid [Cu2(L)2(γ‐Mo8O26)0.5(H2O)]•H2O (CuLMo8) [L = 5‐(pyrimidyl)tetrazolate] was hydrothermally synthesized and fully characterized by various spectral techniques. In the crystal structure of CuLMo8, the μ2‐bridging γ‐Mo8 anion coordinates with Cu ions to extend into a 2D network. CuLMo8 displayed excellent photo‐Fenton‐like catalyst properties for MB degradation under UV light irradiation. Complete decolorization of MB solution was finished in 5 min, and the degradation rate reached 97.9% in 7 min. The degradation rate of the present system was much higher than that of similar systems in the literature. The synergistic effect of CuLMo8 and H2O2 was the fundamental reason for the high degradation rate. Initial pH value and concentration of MB solution, catalyst dosage, and concentration of H2O2 were the main factors to affect the degradation rate. Hydroxyl (•OH) and superoxide (•O2H/O2•‐) radicals were the major reactive species to degrade MB molecules. Moreover, the total organic carbon (TOC) removal was about 37.5% in 3 h, indicating mineralization and decolorization did not take place at the same time. The possible MB degradation pathway was deduced depending on the data gained. In view of the high catalytic efficiency, repeated use, and no need to adjust the pH value of MB solution, this heterogeneous catalyst might have potential to deal with practical wastewater.