Anchoring gold Nanoparticles within the Backbone of POPs to Control their Catalytic Activity

The functional materials research group led by Dr. Mohamed Alkordi, co-director of the Center for Materials science (CMS)at Zewail City, published a study on a novel pathway to immobilize gold (Au) nanoparticles within microporous organic polymers in RSC Advances, published by the Royal Society of Chemistry, on October 4, 2016.

There is a wide scientific interest in the desirable properties of gold (Au) nanoparticles, especially in sensing of biological molecules and catalysis, which urged scientists to investigate several alternative pathways to harness such desirable attributes of the Au nanoparticles.

Au nanoparticles can be used in solution form, however recycling such formulations for subsequent catalytic runs is challenging. In Addition, their size which is few nanometers will make it very challenging to recycle filter from a reaction mixture for reuse.

The research team designed a strategy using porous organic polymer (POPs) to help immobilizing the Au nanoparticles while allowing access of small reactants to reach them. They started by anchoring specific organic molecules on the surface of the Au nanoparticles to act as handles, through which a subsequent reaction can build a microporous polymer around the Au spheres. The permanent microporosity of the POPs containing the Au nanoparticles was shown in the article, where the pore size inside the POPs is determined by its molecular precursors. Also, the loading of Au nanoparticles inside the composite can easily be managed by controlling the ratio of the reactants at the beginning of the reaction.

The team then utilized electrochemical measurements techniques to show how the polymer controlled the reactants’ access to the surface of the Au nanoparticles, and by doing so altered the reactivity of it in relation to the reactant molecular size.

This work was conducted to open new doors for more practical utilization of metallic nanoparticles, Au in this case, targeting application in heterogeneous electrocatalysis. This project was funded by the Zewail City startup fund and STDF grant ID-6125.