Synthesis And Properties Of Au/CuO Nanosheets Composite

Cupric oxide (CuO) is an important p-type semiconductor, which has been extensively studied owing to its different applications, including glucose sensing and as an oxidation catalyst for CO. Gold in bulk is considered chemically inert and has often been regarded to be poorly active as a catalyst. However, when gold is small enough, surprisingly it turns out to be active for many reactions such as CO oxidation and glucose detection. Here, we deposited Au nanoparticles (NPs) on CuO nanosheets (NSs) by mixing NaAuCl4 solution and CuO NSs colloidal solution. Negatively charged [Au(OH)4]-1 was adsorbed onto the surfaces of positively charged CuO NSs by electrostatic attraction. The precipitate of [Au(OH)4]-1/CuO NSs was collected and reduced to Au NPs/CuO NSs (named as Au/CuO NSs) by sodium citrate and thermal reduction, respectively. The Morphology and structures were measured SEM, TEM, HRTEM, SAED, XRD, EDS, and the catalytic oxidation of CO and sensitivity for glucose by using these Au/CuO NSs composites were evaluated by electrochemical analyzer and on-line gas chromatograph. The research in detail as follows:(1) CuO NSs colloid solution was prepared by mixing AE aqueous solution with Cu(NO3)2 aqueous solution, and then prepared[Au(OH)4]-1/CuO NSs precursor with DP method. To prepare Au/CuO NSs composite, sodium citrate reduction processe was used to convert the adsorbed [Au(OH)4]-1 ions on CuO NSs to Au NPs on CuO NSs. Otherwise, the reduction would not finish or the Au nanoparticle would assemble too far even formed the structure of network. The Au/CuO NSs composites prepared with [Au(OH)4]-1/CuO precursor aqueous solution of 1L and sodium citrate aqueous solution(0.1M) of 5ml were distributed with Au nanoparticles more dispersed and uniformly, thus the performance of electrochemical non-enzymatic detection for glucose and Catalytic CO oxidation were much better than others.(2) The CuO NSs colloid solution and [Au(OH)4]-1/CuO NSs precursor in the same way as above. Then the [Au(OH)4]-1/Cu0 NSs precursor were filtrated from the solution, cleaning and drying. To prepare Au/CuO NSs composite the dring [Au(OH)4]-1CuO NSs precursor would be calcined in tube furnace at 200℃ and 400℃ for different time. However, the Au nanoparticle would assemble too far at 400℃, and the time of calcination had little influence on the amount as well as size of the nanoparticle loading on the CuO NSs. The size of the Au nanoparticles formed by thermal reduction had a broad distribution in the range from 10 to 35 nm. Au/CuO NSs composite prepared by thermal reduction had better catalytic oxidation activity of CO than CuO NSs and Au/CuO NSs composite at low temperature reduced by sodium citrate, due to the uniform distribution of Au NPs on CuO nanosheets as well as the strong adhesion between Au NPs and CuO NSs.