New Polymer Colloidal and Carbon Nanospheres: Stabilizing Ultrasmall Metal Nanoparticles for Solvent-Free Catalysis

Herein, we report the synthesis of new colloidal polydiaminopyridine (PDAP) nanospheres with uniform particle size tuned from 76 to 331 nm. The polymer colloidal nanospheres and thin films assembled by the nanospheres exhibit amphiphilic or superhydrophilic properties, originated from the different polymer surfactants. In addition, the polymer nanospheres can be easily carbonized into microporous carbon nanospheres with high N content up to 24 wt %, thus enabling a preferred basicity for CO2 adsorption. As-synthesized PDAP show good compatibility that can not only encapsulate typical nanoparticles to form core–shell composite nanospheres but also stabilize noble metal ions to obtain ultrasmall metal nanoparticles (e.g., Pd and Au) during the thermal reduction process by the nitrogen sites from sphere frameworks. The nanocomplex Pd/PDAP-500 shows exceptional activity and high selectivity in the solvent-free oxidation of alcohols with O2.