Gold nanoparticles self-assemble on the thiol-functionalized fibrous silica microspheres to produce a robust catalyst

A new type of catalyst based on thiol-functionalized fibrous nano-silica material (DFNS-SH) with unique fibrous structure as support and gold nanoparticles (Au NPs) as active sites (DFNS-SH/Au) has been prepared through a facile and environment-friendly self-assembly approach. The synthetic procedure involves the Au NPs prepared in mild conditions instantaneously self-assembled onto the DFNS-SH. The as-synthesized catalyst exhibits a remarkable higher catalytic activity in the reduction of 4-nitrophenol compared with other recently reported related catalysts. Furthermore, DFNS-SH/Au has an outstanding recyclability, after repeated use for many times, obvious activity loss did not occur until the eleventh time. The excellent catalytic activity and robust recyclability are attributed to the synergistic effect between the DFNS-SH and Au NPs. Numerous nano-fibers appear on DFNS-SH, which effectively enhance the mass diffusion and transport in catalytic reactions. Additionally, the enough strong interaction between the Au NPs and thiol groups onto the surface of DFNS can efficiently protect the Au NPs from aggregation and also endow the DFNS-SH/Au with enhanced stability. Thiol groups are also beneficial for improving the Au loading, decreasing the NPs size, reducing their aggregation and improving the catalytic performance of Au NPs anchored on the DFNS-SH as much as possible. This synthetic method discovers an eco-friendly path to effectively prepare low-budget Au-based catalysts and is promising for the development of other excellent materials.