Au-Ag合金纳米粒子的绿色制备及其催化还原性能研究

Green synthesis and catalytic reduction performance of Au-Ag alloy nanoparticles

以AgNO_(3)和HAuCl_(4)为前驱体,以羧甲基壳聚糖(CMC)同时为还原剂和稳定剂制备了金银合金纳米粒子(Au-Ag ANPs),研究了反应温度、时间、NaOH和CMC浓度的影响。通过紫外-可见吸收光谱(UV-Vis)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射(XRD)对Au-Ag ANPs进行了表征。考察了Ag_(0.5)Au_(0.5)投加量、4-NP/NaBH_(4)摩尔比、反应温度和不同条件下制备的Au-Ag ANPs对水溶液中4-硝基苯酚(4-NP)的催化还原性能的影响。结果表明:通过控制Au-Ag ANPs制备时AgNO_(3)和HAuCl_(4)的体积比(V AgNO_(3)/V HAuCl_(4))即可灵活调整Au-Ag ANPs中Au、Ag元素的含量。相同V AgNO_(3)/V HAuCl_(4)时,NaOH和CMC浓度也会影响Au-Ag ANPs中Au、Ag元素的含量。Au-Ag ANPs的平均粒径在(4.5±1.2)nm(Ag_(0.8)Au_(0.2))至(6.5±1.3)nm(Ag_(0.2)Au_(0.8))之间,均小于AuNPs[(16.8±3.7)nm]和AgNPs[(11.7±1.4)nm]的平均粒径。不同Au、Ag元素含量的Au-Ag ANPs对4-NP的催化还原活性均大于AuNPs和AgNPs。在30℃,催化剂投加量60μL,4-NP/NaBH_(4)=1/500时,催化反应30min,Au_(0.6) Ag_(0.4)对4-NP的转化率为91.1%,反应速率常数为0.1289min^(-1)。

Gold-silver alloy nanoparticles(Au-Ag ANPs)were synthesized with AgNO_(3)and HAuCl_(4)as precursors and carboxymethyl chitosan(CMC)as both reducing agent and stabilizer.The effects of reaction temperature,time,NaOH and CMC concentration on the properties of the Au-Ag ANPs were studied.Au-Ag ANPs were characterized by ultraviolet-visible absorption spectroscopy(UV-Vis),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR)and X-ray diffraction(XRD).The effects of Ag_(0.5)Au_(0.5)dosage,4-NP/NaBH_(4)molar ratio,reaction temperature and the different synthesis conditions of Au-Ag ANPs on the catalytic reduction performance of 4-nitrophenol(4-NP)in aqueous solution were investigated.The results showed that the contents of Au and Ag elements in Au-Ag ANPs could be flexibly adjusted by controlling the volume ratio of AgNO_(3)and HAuCl_(4)(V AgNO_(3)/V HAuCl_(4))during the synthesis of Au-Ag ANPs.When V AgNO_(3)/V HAuCl_(4)was the same,the concentration of NaOH and CMC also affected the contents of Au and Ag elements in Au-Ag ANPs.The average particle size of Au-Ag ANPs ranged from(4.5±1.2)nm(Ag_(0.8)Au_(0.2))to(6.5±1.3)nm(Ag_(0.2)Au_(0.8)),which was smaller than that of AuNPs(16.8±3.7nm)and AgNPs(11.7±1.4nm).The catalytic reduction activities of Au-Ag ANPs with different Au and Ag contents on 4-NP waere higher than those of AuNPs and AgNPs.The catalytic reaction was performed for 30 min at 30℃with a catalyst dosage of 60μL and 4-NP/NaBH_(4)of 1/500,and the conversion rate of Au_(0.6) Ag_(0.4) to 4-NP was 91.1%and the reaction rate constant was 0.1289min^(-1).