Studies on the Effect of the Capping Materials on the Spherical Gold Nanoparticles Catalytic Activity

Abstract

Size-controlled gold nanoparticles (AuNPs) were prepared in the presence of different capping materials (sodium citrate, cetyltrimethylammonium bromide (CTAB), and chitosan). The results obtained suggest that the AuNPs were synthesized with different particle size, which is controlled by changing the molar ratio between sodium citrate, (CTAB), and chitosan to Au (III). The catalytic activities of the AuNPs with different capping materials were studied for 4-nitrophenol reduction by NaBH4 as a model reaction. AuNPs with different capping materials is comparable from the value of the apparent rate constant of 4-nitrophenol reduction (0.6 × 10–3, 1.9 × 10–3, and 2.4 × 10–3 s–1) for sodium citrate, CTAB and chitosan. From the results, it is concluded that, AuNPs catalyzed the electron transfer process between and nitro compounds with all the capping materials used AuNPs capped by chitosan were more active for the reduction than the other two.