Figure 3: Nanoscale mapping of electrochemical oxygen redox process at room temperature.

(a) Topographic image of the nanoscaffold SDC–STO film surface. The bright circular regions of ∼30 nm diameter are the SDC columns intersecting the film surface. The image size is 300 × 300 nm². Scale bar, 60 nm. (b) The bias waveform used for ESM measurement. (c) Spatial map of the ESM resonance frequency analysed using a simple harmonic oscillator model fitting, measured at the dc bias of −7 V. The open triangles in a,c show that the probing regions are identical. (d) ESM hysteresis loops with the maximum voltage of 10 V, averaged over one particular SDC column and its surrounding STO region, represented by the open box in h. (e–h) Spatial maps of ESM hysteresis loop area as a function of the peak bias. (i) ESM loop areas as a function of the peak bias averaged over the 30 points of the SDC and STO regions.