Flower-like Co3O4 microstrips embedded in Co foam as a binder-free electrocatalyst for oxygen evolution reaction

Abstract Designing appropriate oxygen evolution reaction (OER) electrocatalysts to meet the requirements of high efficiency, long-term durability, and low cost remains the challenge for scientific community. Cobalt oxide (Co3O4) has been proven as a promising candidate for OER with attractive activity and stability in alkaline media. In this study, flower-like Co3O4 microstrips have been successfully prepared and directly embedded in Co foam (denoted as Co3O4@Co foam) by a green and facile two-step strategy including hydrothermal treatment and subsequent annealing process under relatively low temperatures. It demonstrates that the OER performance of the Co3O4@Co foam electrode can rival to the commercial RuO2 on glassy carbon electrode. The Co3O4@Co foam electrode displays high OER activity with a low overpotential of 273 mV at a current density of 10 mA cm−2, and a low Tafel slope of 61.8 mV dec−1. The flower-like Co3O4 microstrips greatly increase the active surface area to expose more active sites, and the directly growth of Co3O4 microstrips on Co foam with intimate contact improves the electron transport and ensures the stability of the Co3O4@Co foam electrode.