Adsorption behaviors and vibrational spectra of hydrogen peroxide molecules at quartz/water interfaces.

The effect of HO concentration on the change of H-bonds at a water/quartz interface was systematically examined by surface-specific sum-frequency generation (SFG) spectroscopy. Molecular dynamics (MD) simulation was further utilized to interpret the specific molecular dynamics as well as the configuration and evolution of water and HO molecules at the interface. The results from this study demonstrated the important role of surface H-bonds on determination of the stability of adsorbed HO at solvated, silica, xerogel surfaces. It was revealed that prior to reaching the surface saturation with HO molecules (less than 20% in bulk solution), multiple H-bonds were formed with silanols at relatively short interactive distances. These H-bonds proved to be strong enough to enable the overall stability of adsorbed HO. However, once saturated, the HO molecules would be adsorbed at longer distances away from the surface, and could easily migrate to the bulk solution; therefore, in this case, the bonds failed to support stable HO adsorption. These new findings explained the detailed molecular mechanism of the relationship between HO concentration and HO stability in HO-silica xerogels. This solves the current challenge of effective HO storage, and provides fundamental insight for predicting the adsorption behavior of HO at the silica surface.