Fig. 21. (a) LSV curves for OER measured at a scan rate of 5 mV s⁻¹; (b) the overpotential of ZnCo-UF at the current density of 5 mA cm⁻²; (c) corresponding Tafel plots; (d) EIS Nyquist plots at 1.8 V. Reproduced with permission from ref. 94. Copyright 2019 Elsevier Inc.