Galvanic Replacement Mediated Synthesis Of CuS-Au Nanocomposites For Catalytic Applications

Galvanic replacement mediated synthesis of noble metal nanomaterials is a novel synthesis method, which involves a corrosion process that is driven by the difference in the electrochemical potentials of two species. There are no capping agent and surface active agent in this process, it is a simple method for synthesis noble metal nanomaterials with a clean surface, and it has became a new direction for preparation of noble metal nanomaterials and their nanocomposites.In this paper, we prepared Cu2 O nanoparticles with controllable morphologies by a solvent method on the first step, then used Kirkendall effect for preparing Cu7S4 nanocages and Galvanic replacement reaction for Cu S-Au nanocomposites(NCs). We synthetized three kinds of morphology of Cu S-Au NCs by controlling the shape of Cu2 O nanoparticles, and a series of Cu S-Au NCs with different load quantity, different particle size and different distribution through adjusting the concentration of HAu Cl4, categorys of solvent and reaction temperature, respectively. The morphologies, structures and compositions of Cu S-Au NCs were characterized by TEM, SEM and XRD.Finally, we tested the catalytic properties of as-prepared Cu S-Au NCs, combined with UV-Vis spectroscopy and Surface-enhanced Raman spectroscopy(SERS), and we found that the Cu S-Au NCs have good performance in photocatalytic degradation of Rhodamine B(Rh B), catalytic reduction of 4-nitrophenol in the presence of Na BH4 and plasmon-driven reaction for 4-nitrothiophenol(4-NTP). Cu S plays a major role in the process of photocatalytic degradation, and Au NPs are essential to catalytic reduction reaction. In the process of plasmon-driven reaction, the Cu S-Au NCs exhibit better catalytic performance than Au NPs, which mainly ascribes to the photothermal effect of Cu S. In our extending research, we found that the small size of Au NPs are applicable to photocatalytic and catalytic reduction reactions, while the big size of them are beneficial to plasmon-driven reaction. In addition, the power of laser mainly affects the velocity of plasmon-driven reaction, and the atmosphere impacts on the percent conversion, the degree of 4-NTP convert into DMAB is greater in N2 than air atmosphere.