The composition dependent structure and catalytic activity of nanostructured Cu–Ni bimetallic oxides†
Nanostructured bimetallic oxides have received a great amount of attention in the field of catalysis. Here, the influence of composition on the structure and catalytic activity of CuO/NiO bimetal oxides is reported. Oxides with different ratios of Cu : Ni (0 : 100, 25 : 75, 50 : 50, 75 : 25 and 100 : 0) were prepared via a hydrothermal process and subsequently heat-treated at 600 °C for 4 h. XRD and Raman spectroscopic analysis clearly indicated the co-existence of NiO and CuO phases in the bimetallic oxides. Electron microscopy studies revealed a reduction in particle size for the bimetallic oxide compared to the monometallic oxide. The highest catalytic activity with good recyclability for the reduction of 4-nitrophenol was observed with Cu50Ni50–600, having a rate constant of 5.08 × 10−3 s−1. Cyclic voltammetry investigations confirmed the high reactivity of Cu50Ni50–600 for 4-nitrophenol, showing a high oxidation current peak compared to that of other samples. The results show that the presence of CuO and NiO enhances the catalytic activity by their synergetic effect, unlike the monometal oxides.