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Theory for Potential of Zero Charge and Capacitance on Metals with Nanocorrugated Steps

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journal contribution
posted on 12.11.2021, 21:05 authored by Gaurav Kumar Mishra, Rama Kant
We develop the mean-field theory for the step density-induced anomalous variation in electronic capacitance, work function (WF), potential of zero charge (PZC), and interfacial capacitance (IC) of an electrode. The random nanocorrugated step geometry has the functional form as a hyperbolic tangent with a random step edge. The average PZC and IC along with WF expression is obtained as a function of mean-square gradient and mean curvatures. The theoretical result highlights the anomalous non-monotonic lowering of the average PZC and WF with increasing step density. This explains the experimental observation for the stepped platinum electrodes. Further, this theory shows nanocorrugation and the nature of metal-driven large suppression in an average WF of ≈ 0.7 eV, a PZC of ≈ 0.5 eV, and an IC of ≈ 1.4 μF/cm2 from its planar value. Finally, this theory predicts that the step curvature and the step density cause significant variation in electronic WF and PZC, which is consequently the genesis of many anomalies in surface and interfacial phenomena.