Constructing oxygen vacancy-rich MXene @Ce-MOF composites for enhanced energy storage and conversion

The MXene@Ce-MOF electrode material is rich in oxygen vacancies caused by surface defects of Ce-MOF, which makes it have excellent properties of HER, OER and supercapacitor. [Display omitted] •MXene promotes the generation of surface defects in Ce-MOF, which in turn leads to the generation of oxygen vacancies.•The surface of single layer MXene contains a large number of F-, which not only plays a role in attracting cerium ions, but also contributes to improve the hydrophilicity of electrode materials.•The introduction of MXene can further enhance the electrical conductivity of Ce-MOF, and also increase the reactive active site. Oxygen vacancies can regulate the coordination structure and electronic states of atoms, thus promoting the formation of surface-active sites and increasing the conductivity of the electrode material. This work presents a design for MXene@Ce-MOF composites with abundant oxygen vacancies. The hydroxyl groups on the surface of monolayer MXene attract cerium ions, which create surface defects in Ce-MOF and further promote the formation of oxygen vacancies. This results in a significant improvement in energy storage capacity, as well as performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The MXene@Ce-MOF composite exhibits a specific capacity of 496 F g−1, which is 1.8 times higher than that of pure Ce-MOF and 3.5 times higher than MXene alone. At a current density of 10 mA cm−2, the overpotential for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is as low as 270 and 220 mV, respectively, and the composite exhibits excellent cycling stability. Oxygen vacancy-based MOF composites play a crucial role in electrocatalysis and energy conversion.