New insights into HER catalysis: the effect of nano-silica support on catalysis by silver nanoparticles.

Supported metal catalysts have recently attracted considerable attention in the field of catalysis. The effect of surface chemical groups (SiO-/SiOH2+) on SiO2-Ag0-NPs along with the average negative charge induced by (CH3)2COH˙ radicals on the catalytic reduction of H2O/H3O+ towards the hydrogen evolution reaction (HER) is reported. The results indicate that similar effects are observed both above and below the point of zero charge (PZC) of silica. More importantly, it is shown that a high concentration of this catalyst does not necessarily contribute to boosting the hydrogen formation, but instead, the density of charge on its surface is a decisive factor. A mechanistic explanation of the observed effect is given.