“…So, the Ni@CCO2 electrode had the fastest OER kinetics. The required overpotential to reach the benchmarked current density of 10 mA cm −2 and the Tafel slope of the Ni@CCO2 electrode were better than or close to the non-precious metal oxide catalysts reported in the literature (Table S2, ESI†), such as delafossite oxide, including CuCoO 2 ( η 10 = 390 mV, Tafel slope = 70 mV dec −1 ), 13 Ni doped CuCoO 2 ( η 10 = 409 mV, Tafel slope = 98 mV dec −1 ), 19 Fe doped CuCoO 2 ( η 10 = 369 mV, Tafel slope = 69 mV dec −1 ), 20 Ca doped CuCoO 2 ( η 10 = 470 mV, Tafel slope = 96.5 mV dec −1 ), 18 CuGaO 2 ( η 10 = 400 mV, Tafel slope = 61 mV dec −1 ); 25 or other perovskite oxide electrocatalysts, including LaFeO 3 ( η 10 = 420 mV, Tafel slope = 62 mV dec −1 ), 43 La 0.9 Sn 0.1 NiO 3− δ ( η 10 = 318 mV, Tafel slope = 74 mV dec −1 ), 47 La 1− x Sr x CoO 3− δ ( η 10 = 326 mV, Tafel slope = 70.8 mV dec −1 ), 48 and LaNiO 3 ( η 10 = 460 mV, Tafel slope = 96 mV dec −1 ). 49…”