Cu2O/MWCNTs Prepared by Spontaneous Redox: Growth Mechanism and Superior Catalytic Activity

Abstract

To elucidate the growth mechanism of Cu2O/MWCNTs synthesized by spontaneous redox reaction, the evolution of copper oxides was investigated during the synthesis process. It was found that the pH of the reaction system and defects in MWCNTs play an important role for Cu2O/MWCNTs formation. According to the calculation of oxidation and reduction potentials at different conditions, only pH 9 satisfies conditions for the formation of Cu2O/MWCNTs thermodynamically in the presence of NH3·H2O which is used for adjusting the pH of reaction system. The high defect density of MWCNTs is favorable for Cu2O/MWCNTs synthesis dynamically. For spontaneous redox, Cu2O NPs are located on the defect sites of CNTs, and a strong interaction is formed between defects and Cu2O, which could promote electron transfer in catalysis. Thus, the as-prepared Cu2O/MWCNTs show catalytic performance superior to that of the catalysts prepared by a hydrothermal method or other methods in the hydrogenation of benzene to cyclohexane.