Novel vacancy-rich Co3O4/VO2 nanohybrids for enhanced electrocatalytic performance and application as oxygen evolution electrocatalysts

Abstract

Structure and defect control are effective strategies to manipulate the activity and stability of catalysts. Herein, a novel hollow and defect-rich Co3O4/VO2 nanohybrids (NHs) is synthesized with zeolitic imidazolate framework-67 (ZIF-67) nanocrystal as the template to anchor VO2 nanoparticles (NPs) for enhanced electrocatalytic performances. The changes of chemical composition, crystalline structure, oxygen vacancy concentration, phase boundaries of the interface between Co3O4 and VO2 are detailedly studied by TEM, XPS, ESR and UV–vis absorbance spectra, so as to clarify the interface effect of nanohybrids comprising of two transition metal oxides on its OER activity. The as-prepared oxygen vacancy-rich Co3O4/VO2 NHs show excellent electrocatalytic performance with a lower overpotential at the current density of 10 mA cm−2 for oxygen evolution reaction (OER), which decreases in 100 mV as compared to that of Co3O4. These results confirm that the introduction of defect in the interface can not only provide more available catalytic active sites, but also efficiently stabilize the interfacial structure of the nanohybrids by depleting the stress. The greatly improved electrochemical performance of Co3O4/VO2 NHs demonstrates the importance of rational design and control of vacancy defects, which may offer a step forward in the design of advanced hybrid nanomaterials.