【作者】 李冬冬； 赵宁； 徐坚；

【Author】 Dongdong Li;Ning Zhao;Jian Xu;Beijing National Laboratory for Molecular Science, Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences;

【机构】 北京分子科学国家实验室中国科学院化学研究所高分子物理与化学实验室；

【摘要】 贵金属纳米颗粒由于其大比表面积和高表面原子活性而对各种化学反应表现出优异的催化活性[1-3],然而,颗粒易聚并、难回收的问题限制了其应用。本文以Fe₃O₄微球作为磁性内核,包覆二氧化硅后再经TA（单宁酸）-Fe LbL表面改性和原位还原,制备出磁性高效Ag纳米催化剂。研究发现,相较于传统TA-Fe络合改性,TA-Fe LbL改性可有效地消除改性后颗粒易黏连,改性不均匀及易生成粘附络合物杂质的现象。得益于TA分子内大量酚羟基对催化反应物的富集作用和致密粘附的小粒径Ag NPs（粒径仅5～7 nm）高活性,所制备材料在催化硼氢化钠还原4-硝基苯酚的反应中表现出优异的催化活性,表观速率常数达0.430 min^-1,且磁性材料易于分离回收和循环利用。单宁酸改性及原位还原Ag NPs无需使用有毒危险还原剂,绿色、安全。借助TA的还原性及其优异粘附性,此方法还可拓展至其它曲面改性和还原贵金属纳米颗粒,用于制备新型高效催化材料。更多还原

【Abstract】 Noble metal nanoparticles（NMPs） display unexpectedly high catalytic activities toward different types of reactions due to their large specific surface area and high surface atomic activity[1-3]. However, the fact that the particles are easily aggregate and difficult to recycle limits their application. In this article, magnetic Ag nanocatalyst was prepared by using Fe₃O₄ microspheres as magnetic cores and TA-Fe LbL modification. Compared with traditional TA-Fe complex modification, TA-Fe LbL modification can effectively eliminate the agglomeration of particles and the coating is more uniform, in addition, this method can inhibit the production of free complex impurities. Benefited from the enrichment of the catalytic reactants by a large amount of phenol hydroxyl in the TA molecule and densely deposited small Ag NPs（5～7 nm）,The prepared materials show excellent catalytic activity in the reduction of 4-nitrophenol with NaBH₄: the rate constant is 0.430 min^-1. Furthermore, the magnetic core facilitates the convenient recovery and reuse of the catalyst and the TA insitu reduction is environmental friendly. This method can be extended to the modification of other surfaces with high curvature and guide the development of new and efficient catalytic materials.更多还原