MOF-derived core-shell MnO@Cu/C as high-efficiency catalyst for reduction of nitroarenes

The design of catalysts for competitive pricing and high-performance reduction reactions has attracted increasing attention. The low resistance to aggregation and sintering as well as the uneven size distribution during reaction and preparation of such catalysts, considerably limit their practical applications. This paper presents the preparation of highly stable copper nanoparticles (Cu-NPs) by coating MnO2 nanorods with Cu metal-organic frameworks (MOF) via simple layer-by-layer assembly. The high-temperature reduction of MnO2/Cu-MOF generates MnO/Cu-C as catalyst. The obtained Cu-NPs in a Cu/C@MnO catalyst, with partially uncovered free active surfaces, are encapsulated by a carbon-matrix. This unique structure, with homogeneously distributed CuNPs in the carbon matrix, significantly retards the sintering and oxidation of the Cu-NPs in solution. Excellent activity (100 % conversion in 90 s) and recyclability after six cycles [>98 % (conversion) in 120 s] in water are achieved for the reduction of 4-nitrophenol by sodium borohydride (NaBH4) under mild conditions. This high performance is attributed to the high adsorption ability of the carbon matrix and the high catalytic activity of CuNPs on the MnO surface. This study provides novel MOF-derived catalysts for use in various valuable applications.