Electrochemical oxidation induced in-situ transformation of lamellar cobalt nitrate-hydroxide to oxygen vacancy-rich porous Ce Doped-CoOOH nanosheet for efficient oxygen evolution reaction

Two-dimensional transition metal (2D TM)-based oxyhydroxides are widely used for electrocatalytic oxygen evolution reaction (OER) due to their high activity and low price. However, the limited active sites and insuf-ficient intrinsic activity restrict their commercial applications. In this work, we develop a novel electrochemical oxidation etching-induced in-situ doping strategy to construct two-dimensional (2D) oxygen vacancy (Ov)-rich porous Ce-doped CoOOH ultrathin nanosheets consisting of ultrafine nanocrystals on carbon cloth (Ce-CoOOH/ CC) using lamellar cobalt nitrate-hydroxide on CC (CoLNH/CC) as the precursor for electrocatalytic OER. Benefiting from the abundant active sites and efficient mass/electron transfer rooted in the 2D ultrathin porous structure, as well as the optimized electronic structure resulting from Ce doping and Ov introducing, the Ce-CoOOH/CC exhibits a superior OER activity, with a low overpotential of 306 mV at 50 mA cm-2 and a small Tafel slope of 72.2 mV dec-1, compared to that of Co LHN/CC (368 mV and 93.9 mV dec-1), CeO2/Co LHN/CC (359 mV and 94.3 mV dec-1), and CoOOH/CC (337 mV and 75.9 mV dec-1) counterparts. Meanwhile, it shows good stability, with negligible current attenuation after 3000 cyclic voltammetry cycles or 24 h of continuous test. This study provides a feasible strategy for constructing various metal-doped porous transition metal oxyhydroxide-based electrocatalysts.