However, the effect of strain on the reaction is still not well understood, especially with respect to diverse reaction and/or their pathways. A suitable measure to quantify this interaction are coupling coefficients, i.e. between the applied strain and the conversion current.
We present an approach to directly quantify this coupling between elastic surface strain to the canonical reaction of methanol oxidation based on the model system of planar gold (which is commonly regarded a catalytically inactive element). Two different strategies (Fig. 1) can provide access to the desired effect. We apply a controlled sine-circled strain with fixed frequency on an elastically deformable substrate carrying the gold thin film and adopt a lock-in technique to capture the modulated synchronous electric response during the whole methanol oxidation reaction process. Through this method, we can obtain the electrocapillary coupling coefficients as functions of the applied potentials, i.e. of each individual reaction step so that the method provides an access to the underlying mechanism (composed of steps of capacitive charging, O adsorption and methanol oxidation) which is not given by common cyclic voltammetry.
The obtained results show that strain significantly modifies the electrochemical surface properties as we thought, an obvious rise of the electrochemical sign in both potential-strain (ς) and current-potential coefficient (Λ) when methanol start to oxidize.