From
atomic force microscopy (AFM) experiments, we report a new
phenomenon in which the dissolution rate of fused silica is enhanced
by more than 5 orders of magnitude by simply pressing a second, dissimilar
surface against it and oscillating the contact pressure at low kHz
frequencies in deionized water. The silica dissolution rate enhancement
was found to exhibit a strong dependence on the pressure oscillation
frequency consistent with a resonance effect. This harmonic enhancement
of the silica dissolution rate was only observed at asymmetric material
interfaces (e.g., diamond on silica) with no evidence of dissolution
rate enhancement observed at symmetric material interfaces (i.e.,
silica on silica) within the experimental time scales. The apparent
requirement for interface dissimilarity, the results of analogous
experiments performed in anhydrous dodecane, and the observation that
the silica “dissolution pits” continue to grow in size
under contact stresses well below the silica yield stress refute a
mechanical deformation or chemo-mechanical origin to the observed
phenomenon. Instead, the silica dissolution rate enhancement exhibits
characteristics consistent with a previously described ‘electrochemical
pressure solution’ mechanism, albeit, with greatly amplified
kinetics. Using a framework of electrochemical pressure solution,
an electrochemical model of mineral dissolution, and a recently proposed
“surface resonance” theory, we present an electro-chemo-mechanical
mechanism that explains how oscillating the contact pressure between
dissimilar surfaces in water can amplify surface dissolution rates
by many orders of magnitude. This reaction rate enhancement mechanism
has implications not only for dissolution but also for potentially
other reactions occurring at the solid–liquid interface, e.g.
catalysis.