Ligand-free gold nanoparticles supported on mesoporous carbon as electrocatalysts for CO2 reduction

Matteo Miola, Xin-Ming Hu, Riccardo Brandiele, Emil Tveden Bjerglund, Didrik Konow Grønseth, Christian Durante Steen Uttrup Pedersen, Nina Lock, Troels Skrydstrup,  KimDaasbjerg

Gold nanoparticles (AuNPs) have shown good catalytic activity for electrochemical CO2 reduction. However, they are typically stabilized by poorly conductive organic ligands which partially block their activity for electrocatalysis. In this work, we report a one-pot organic ligand-free synthesis of AuNPs on mesoporous carbon (MC). The size of the AuNPs is controlled by the micro- and mesoporosity of the carbon support and the mass ratio employed of the gold precursor/MC. The produced AuNPs-MC hybrid material, with the largest amount of small AuNPs (1–3 nm), shows good catalytic activity for the electrochemical reduction of CO2 to CO in aqueous electrolyte. The optimized selectivity is recorded to be, on average, 80% with a mass activity of 12.8 A g–1 at an overpotential of 550 mV. The catalyst stability of the material is investigated to give insight into the irreversible deactivation mechanism occurring at the surface of AuNPs. Using 6-mercapto-1-hexanol as the ligand on AuNPs shows a dual effect in terms of an improved stability but a lowered activity.