Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO2 Reduction

Abstract

N-heterocyclic carbenes (NHCs) have recently gained significant attention as capping ligands for gold nanoparticles due to their strong σ-donation properties. It has already been established that the strong σ-donation of NHCs enriches the surface of the gold nanoparticles, which controls the catalytic activity of the metal nanoparticles. Cyclic (alkyl)(amino)carbene (CAAC) is a special class of carbene that offers stronger σ-donation than NHCs. This extremely electron-rich nature of CAAC projects it as a better surface capping ligand upon extrapolation on the Au(0) surface. In this work, we have isolated stable CAAC-stabilized AuNPs via a ligand exchange method and studied their catalytic behavior toward electrochemical CO2 reduction. These newly synthesized CAAC-stabilized AuNPs furnish a remarkable faradaic efficiency (FE) of 94% [at pH 6.3 for 2 h of controlled potential electrolysis at −0.7 V vs NHE (normal hydrogen electrode)] toward selective CO formation. Our work sets the platform for CAAC as a robust main group ligand on the surface of different metal nanoparticles, bridging the gap between main group ligands and surface chemistry.