银纳米粒子的制备及对4-硝基苯胺的催化还原作用

Preparation of Silver Nanoparticles for Catalytic Reduction of 4-Nitroaniline

采用氢气还原法制备了粒径为40-60nm的银纳米粒子．通过紫外可见吸收光谱现场跟踪了其对硼氢化钠还原4-硝基苯胺反应的催化作用．并利用表面增强拉曼散射技术研究了反应体系中各物质与催化荆表面的作用方式．结果表明：4-硝基苯胺通过硝基与银纳米粒子的直接接触，并以银纳米粒子为中转站实现了电子的传递。在室温下极大地加速了对4-硝基苯胺的还原反应：催化剂用量和还原剂用量的增加可明显加快催化还原反应的速度．

Silver nanoparticles in 40-60 nm diameter are prepared using hydrogen as reducing agent, The excellent catalytic activity of these silver nanoparticles for the reduction of 4-nitroaniline by sodium borohydride is easily monitored by the spectroscopic methods. Moreover, the mode of interaction between each substance in the reaction system and the catalyst is studied by surface-enhanced Raman scattering. The results indicate that 4-nitroaniline can direct contact with silver nanoparticles through nitro, and the silver nanoparticles function as an electron relay for the electron transfer, resulting in the great acceleration of 4-nitroaniline reduction reaction at room temperature. The influence of the amount of catalyst, reducing reagent and the reaction time on the reduction reaction are also studied. The results indicate that the increase in the amount of catalyst and reducing reagent significantly accelerate the catalytic reduction reaction speed.