No abstract

Silver‐based catalysts are attractive for electroreduction of CO2 to CO. To understand the electrocatalyst properties, a good control over the nanoparticle size is necessary. Herein, we report a strategy to synthesize highly dispersed, ligand‐free silver Ag nanoparticles supported on carbon. We demonstrate that the heat treatment atmosphere and carbon surface chemistry are crucial to control the Ag particle size in the 10–30 nm range. Even at low silver loadings (0.099 m2Ag m−2), Ag nanoparticles outperforms the bulk silver at low overpotentials, leading to a 23.5 % CO Faradaic efficiency at −1.2 V vs RHE. The Ag weight‐based activity of the catalysts scales with the inverse particle size, while the Ag surface‐specific activity is independent of the particle size in this range. The supported silver nanoparticles can produce a H2 to CO ratio of 2.9 to 1, interesting for further exploration of this type of catalysts for syngas synthesis.

The electrochemical reduction of CO2 to produce sustainable fuels and chemicals has attracted great attention in recent years. It is shown that surface‐modified carbons catalyze the CO2RR. This study reports a strategy to modify the surface of commercially available carbon materials by adding oxygen and nitrogen surface groups without modifying its graphitic structure. Clear differences in CO2RR activity, selectivity and the turnover frequency between the surface‐modified carbons were observed, and these differences were ascribed to the nature of the surface groups chemistry and the point of zero charge (PZC). The results show that nitrogen‐containing surface groups are highly selective towards the formation of CO from the electroreduction of CO2 in comparison with the oxygen‐containing surface groups, and the carbon without surface groups. This demonstrates that the selectivity of carbon for CO2RR can be rationally tuned by simply altering the surface chemistry via surface functionalization.