Reactions of methyl radicals with silica supported silver nanoparticles in aqueous solutions

•Silica supported silver NPs are efficient catalysts for dimerization of methyl radicals.•Bare silica is inert towards the interaction with methyl radicals.•Ethanol adsorbed on the SiO2 surface changes the reaction path with ·CH3.•Adsorbed ethanol on the well-known Stöber silica prevents its precipitation.

Silica supported silver nanoparticles (Ag°–SiO2–NCs, NCs=nanocomposites) suspended in aqueous solutions are efficient catalysts for the dimerization of methyl radicals to produce ethane, while bare silica is quite inert towards the interaction with methyl radicals. In the presence of small amounts of ethanol adsorbed on the SiO2 surface, the reaction path with methyl radicals is changed and methane is formed as the major product.