Cobalt-doped zinc oxides (Co@ZnO) nanosheets for efficient bifunctional electrocatalytic activity for the oxygen reduction and evolution reactions

As a possible electrocatalyst, a two-dimensional heterostructure made up of a metal that conducts electricity very well and a metal oxide that conducts electricity has been discovered. In this investigation, we utilized co-precipitation strategy as a simple method to synthesize novel two-dimensional nanosheets of cobalt-doped zinc oxide (Co@ZnO). Through a post-annealing process, the cobalt in the hybrid material is stabilized in the + 2 oxidation state, facilitating the transformation of the precursor into crystalline cobalt-substituted zinc oxide nanosheets while preserving the original morphology. Structural and morphological analyses which revealed the characteristics of the synthesized nanosheets. The electrochemical experiments showed that Co doped ZnO (Co@ZnO) nanosheets, with an optimal doping concentration of 2 wt%, demonstrated outstanding electrocatalytic performance for the ORR in a alkaline medium (0.1 mM KOH), exhibiting an onset potential of 0.88 V and a nearly four-electron mechanism. The Co@ZnO nanosheets displayed superior electrochemical stability compared to pristine ZnO for the ORR. Compared to commercially available RuO₂ catalysts, the Co@ZnO catalyst exhibited significant activity in the OER throughout the experiment. It’s likely that the defect sites and porous structure of Co@ZnO nanosheets worked together to make the catalyst so effective in both OER and ORR.