Preparation And Catalytic Performance Of Cu-Mo Composite Catalysts

In this paper,three series of copper-molybdenum composite catalysts were designed and prepared with different reducing agent using MoS₂ and Cu（NO₃）₂·3H₂O as precursors.The catalytic performance was evaluated by catalyzing the reduction of p-nitrophenol（4-NP）,methyl blue（MB）or Rhodamine B（RhB）by NaBH₄.In the first set,copper-molybdenum composite catalyst was prepared with salicylaldehyde as reducing agent.MoS₂ was first prepared under hydrothermal conditions and then mixed with Cu（NO₃）₂·3H₂O and salicylaldehyde to get composite catalyst using a secondary solvothermal process.The catalytic testing showed that the catalytic reduction of 4-NP,MB or RhB in the presence of NaBH₄ by the as-prepard copper-molybdenum composite catalyst was better than any of the components in the composite catalyst.The characterizations by X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）as well as density functional theory calculations（DFT）indicate that the as-prepared copper-molybdenum composite catalysts prepared with salicylaldehyde as reducing agent are composed of Cu₂O and amorphous MoO_xS_y,possessing hollow microspheres with core-shell structure.MoO_xS_y formed on Cu₂O surface hardly changed the morphology of Cu₂O,but it promoted the catalytic performance of Cu₂O.In the second set,copper-molybdenum composite catalyst was prepared with glutaric dialdehyde as reducing agent.MoS₂ was first prepared under hydrothermal conditions and then mixed with Cu（NO₃）₂·3H₂O and glutaric dialdehyde to get composite catalyst using a secondary solvothermal process.The results of powder X-ray diffraction（XRD）analyses show that the copper species in the composite catalysts prepared under different hydrothermal temperatures are different.All the four composite catalysts have good catalytic performance toward the reduction of 4–NP,MB or RhB by NaBH₄,especially the catalytic activity of the as-prepared composite catalyst synthesized at 210℃hydrothermal temperature is comparable to that of noble metal catalysts.In third set,copper-molybdenum composite catalyst was prepared with N-（2-Carboxyphenyl）glycine as reducing agent.MoS₂ was first prepared under hydrothermal conditions and then mixed with Cu（NO₃）₂·3H₂O and N-（2-Carboxyphenyl）glycine to get composite catalyst using using a secondary solvothermal process.The result of powder X-ray diffraction（XRD）analysis shows that the copper species in the composite catalyst is Cu₂O,in the meantime,the morphology of the composite catalyst was observed by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）.The copper-molybdenum composite catalyst and the Cu₂O prepared alone demonstrate superior catalytic activity in the reduction of 4-NP,MB and RhB by NaBH₄,but compared with Cu₂O,the catalytic activity of the composite catalyst is better,and the activity parameter can reach 2335.5 s^-1g^-1.