Atomically dispersed metal catalysts for the oxygen reduction reaction, including their synthesis, characterization, reaction mechanisms and electrochemical energy application, are reviewed.

Nanorods-composed yolk–shell bimetallic-organic frameworks microspheres are successfully synthesized by a one-step solvothermal method in the absence of any template or surfactant. Furthermore, hierarchical double-shelled NiO/ZnO hollow spheres are obtained by calcination of the bimetallic organic frameworks in air. The NiO/ZnO hollow spheres, as supercapacitor electrodes, exhibit high capacitance of 497 F g⁻¹ at the current density of 1.3 A g⁻¹ and present a superior cycling stability. The superior electrochemical performance is believed to come from the unique double-shelled NiO/ZnO hollow structures, which offer free space to accommodate the volume change during the ion insertion and desertion processes, as well as provide rich electroactive sites for the electrochemical reactions.

Cobalt oxide nanowires fabricated on three-dimensional carbon foam (3D) can be used as a promising electrochemical sensing platform for H₂O₂ detection.