Synthesis of silver nanoparticles assisted by chitosan and its application to catalyze the reduction of 4-nitroaniline.

Abstract

This paper reports on the fabrication of material comprised of chitosan stabilized silver nanoparticles on the carbon paste and its electro-catalytic reduction toward 4-nitroaniline. The synthesized material was obtained when AgNO3 was mixed with chitosan as a stabilizing agent and NaBH4 as a reducing agent. The developed Chitosan-AgNPs has been confirmed using UV-Vis spectroscopy, X-Ray diffraction analysis, scanning electron microscopy (SEM) and infrared spectroscopy. The synthesized chitosan-Ag NPs exhibit particle size around 51\u202fnm. To build a voltammetric sensor (Chitosan-Ag NPs/CPE), a carbon paste electrode has immersed in the liquid suspension of chitosan-Ag NPs, thus, it could be employed for electro-catalytic reduction of 4-NA in 0.1\u202fM Britton-Robinson buffer solution (B-R, pH\u202f2). Therefore, the reduction over-potential of 4-NA shifted from -752.26\u202fmV at CPE to -304\u202fmV at chitosan-Ag NPs/CPE, and then showing a surface controlled process with the catalytic rate constant (Kcat) of 0.125\u202f×\u202f10-3\u202fM-1\u202fs-1 and a coefficient of diffusion (D) of 2.20\u202f×\u202f10-6\u202fcm2\u202fs-1 with an enhanced current response. Under optimized conditions, the electro-catalytic reduction peak current of 4-NA increased linearly with increasing of 4-NA concentration over the range of 1\u202fμM to 0.5\u202fmM (R2\u202f=\u202f0.9866) with a detection limit of 0.86\u202fμM (3\u202f×\u202fSb/P).