Constructing hollow nanocages of Co3O4-CoMoO4 heterostructure for efficient electrocatalytic oxygen evolution reaction

Hollow nanocages composed of heterostructures play an important role in oxygen evolution reaction (OER) due to their high electrocatalytic activity induced by the interfacial polarization within the interface of the heterostructure. In this work, ZIF-67 was used to synthesize Co3O4/CoMoO4 hollow nanocages (Co3O4/CoMoO4 HNC). Transmission electron microscopy (TEM) images verify that Co3O4/CoMoO4 HNC was composed of Co3O4/CoMoO4 heterostructures. X-ray photoelectron spectroscopic (XPS) characterizations show that the Mo 3d peaks of Co3O4/CoMoO4 are located at lower binding energy compared with CoMoO4, indicating charge transfer between Co3O4 and CoMoO4. The electrochemical studies show that Co3O4/CoMoO4 HNC exhibited excellent OER activity in an alkaline medium with only 248 mV overpotential required to achieve a current density of 10 mA cm−2. Co3O4/CoMoO4 HNC was tested as the anode material in a homemade water-splitting device to produce oxygen. The Co3O4/CoMoO4 HNC‖20 % Pt/C electrolytic cell shows equivalent performance to RuO2‖20 % Pt/C cell at 50 °C. The excellent OER performance of Co3O4/CoMoO4 HNC is attributed to the interfacial charge transfer between Co3O4 and CoMoO4 which promote the adsorption of OH−. Besides, the hollow nanocage structures provide a large surface area, leading to more active sites for OER.