Spider chrysanthemum-like Co flowers on a Ni foam for highly efficient H2O2 electroreduction in alkaline media

Transition metal oxides have shown potential as hydrogen peroxide (H2O2) reduction catalysts because of their low cost, good catalytic properties, and excellent stability in alkaline solutions. In this study, a CNF-0.25 composite electrode comprising spider chrysanthemum-like Co flowers on a Ni foam is synthesized as an efficient cathode for H2O2 electroreduction in alkaline media. CNF-0.25 exhibited superior stability and highly desirable electrocatalytic properties for H2O2 reduction with a high current density of 0.42 A cm−2 at − 0.5 V. The voltage of an Al-H2O2 semi-fuel cell prepared using CNF-0.25 as the cathode remains stable during a 50 h discharge test. The specific mechanism for the promotion of H2O2 electroreduction using CNF-0.25 is investigated according to the mechanism of H2O2 reduction over a cobalt-based catalyst. The spider chrysanthemum-like Co flowers are mainly composed of metallic Co, which improves the conductivity of the electrode. On the surface of the metallic Co, the presence of a layer of cobalt oxides or hydroxides provides sufficient catalytic active sites (Co2+/Co3+) and prevents further oxidation of internal Co. In addition, the unique spider chrysanthemum-like structure of CNF-0.25 increases the specific surface area of the electrode and facilitates electrolyte transport. This work offers another approach for designing highly efficient transition metal oxide electrodes in alkaline media.