金银双金属纳米粒子的制备及其对4-硝基苯酚的催化还原性能OA

Gold-silver bimetallic nanoparticles(Au-Ag NPs)were successfully synthesized by simulta-neous reduction of HAuCl4 and AgNO3 using water-soluble chitosan(WSC)as the reducing agent and stabilizer.The effects of the volume ratio of gold and silver precursors(V(HAuCl4)/V(AgNO3)),reac-tion temperature and time,NaOH and WSC concentration were investigated.The Au-Ag NPs were characterized by ultraviolet-visible absorption spectroscopy(UV-vis),Fourier transform infrared spec-troscopy(FT-IR),transmission electron microscopy(TEM)and energy dispersive X-ray spectroscopy(EDS).The catalytic reduction performance of Au-Ag NPs towards 4-nitrophenol(4-NP)was investi-gated.The results showed that spherical or nearly spherical Au-Ag NPs with an average particle size of 4 nm were prepared using WSC as the reducing agent and stabilizer.The catalytic reduction activity of Au-Ag NPs towards 4-NP was better than that of AuNPs and AgNPs,and the highest catalytic activity was obtained for Au0.5Ag0.5(V(HAuC14)/V(AgNO3)=1∶1).When Au0.5Ag0.5was used as catalyst,the conversion of 4-NP could reach 99.1％when the catalytic reaction was carried out at 30 ℃ for 30 min,the reaction rate constant was 0.190 3 min-1,and the reaction activation energy Ea was 31.1 kJ·mol-1.