Porous cobalt carbonate hydroxide nanospheres towards oxygen evolution reaction

Cost-effective nonprecious metal nanostructures are considered as highly promising electrocatalysts towards oxygen evolution reaction (OER). Optimizing their morphologies is an efficient strategy to enhance the electroactivity and durability of various electrocatalysts for practical application. Herein, porous cobalt carbonate hydroxide nanospheres (CoCO3 PNSs) are successfully synthesized by using calcium carbonate (CaCO3) nanospheres as a reaction precursor and self-template via a facile precipitation transformation method. Mainly, the solubility constant [Ksp (CoCO3) = 1.4 × 10−13] of CoCO3 is much lower than that [Ksp (CaCO3) = 2.8 × 10−9] of CaCO3, resulting in the successful transformation of CaCO3 nanospheres to CoCO3 PNSs. Physical characterizations reveal that CoCO3 PNSs consist of many tiny subnanorods (length of 50 nm, diameter of 5 nm), which have a high surface area and abundant channels between subnanorods. Compared to irregular cobalt carbonate hydroxide nanoparticles, CoCO3 PNSs reveal enhanced OER performance in KOH solution, including a low overpotential of 310 mV and a small Tafel slope of 56 mV dec−1.