Mesoporous silica dispersed Co₃O₄-CuO nanocomposite and its catalytic reduction of 4-nitrophenol

Abstract

Herein, a catalyst Co3O4-CuO nanocomposite uniformly dispersed on mesoporous silica nanospheres (MSN) has been successfully synthesized through hydrothermal method. The synthesis method is simple and convenient, the prepared Co3O4-CuO nanocomposites have high dispersibility, and the support SiO2 maintains the structure of mesoporous nanospheres. What’s more, the porous structure enables the obtained composite to have a high specific surface area (128.89 m2/g), which is easier to be contacted by catalytic substrates. The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was investigated. The results show that the nanocomposite catalyst Co3O4-CuO@MSN present good catalytic performance, which can completely convert 4-NP to 4-AP in 200 s and the reaction rate constant k is up to 0.149 s-1. More important, the possible degradation mechanism was also proposed in the paper.

Bimetal–Organic Frameworks for High Efficiency Catalytic Reduction

“…As seen in Figure g, it shows good linear correlations of ln( c t / c 0 ) versus t for the reduction reaction. The k app (slope of the linearly fitted plots) is 0.153 s –1 ; the catalytic activity of the CuNi-MOFs (Figure f,g) is 34 times higher than that of Ni-MOFs (0.0045 s –1 , Figure d,e) as well as some novel metals in previous reports − (Table S2). It is worth noting that a higher k app indicates higher catalytic activity in the catalytic reduction of 4-NP by NaBH 4 .…”

“…On the basis of results and recent reports, ,,,− the reduction process with the presence of CuNi-MOF catalysts and NaBH 4 includes (Figure a) (1) chemisorption of BH 4 – on the surface of the MOFs and (2) transfer electrons from BH 4 – to the reactants via the Cu and Ni sites states. The metal site states of MOF can effectively trap and accumulate long-lived electrons, and act as relay for the electrons transfer from BH 4 – to 4-NP, which is a crucial process in real catalytic systems.…”