In situ recyclable gold nanoparticles using CO2-switchable polymers for catalytic reduction of 4-nitrophenol

CO2-switchable gold nanoparticles (AuNPs) were prepared by functionalizing AuNPs with CO2-switchable polymers. Their dispersion–re-dispersion in and separation from aqueous solution can be easily and reproducibly adjusted by CO2 bubbling through and removal from the solution, enabling unique CO2 controllable, efficient in situ recycling of NPs. As compared to non-functionalized AuNPs, they exhibit higher catalytic activity (except for the 1st round), easier separation and better reusability for 4-nitrophenol reduction.