Anchoring metal-organic framework-derived hollow CoV2O6 nanocubes onto lattice tensile strained V2CTx MXene for superior overall water splitting

Abstract

MXene is considered as a kind of promising two-dimensional layered carbide/nitride in the field of overall water splitting attributed to hydrophilic surface, controllable interlayer spacing, and desirable metal conductivity. Nevertheless, the re-stack effect still hinders its large-scale development. Therefore, in this work, metal-organic frameworks-derived hollow CoV2O6 nanocubes anchored on the surface of lattice tensile strained V2CTx MXene (TS-V2CTx/CoV2O6 HN) as electrocatalysts are prepared through ion exchange process and the following liquid nitrogen quenching treatment. Lattice tensile strain could boost ions transfer of transition metals due to the enlarger interlayer spacing. The heterostructure between CoV2O6 and V2CTx MXene could optimize the adsorption energy of H- and O-containing intermediates to obtain the best ΔGH* for hydrogen evolution reaction (HER) and decrease the ΔG value of rate determining step for oxygen evolution reaction (OER). Besides, the CoV2O6 components acting as intercalation agents could avoid the self-aggregation of MXene nanosheets. Simultaneously, the hollow structure also offers high active area to promote electrolyte permeation and accelerate electron/ion transfer. As a consequence, the TS-V2CTx/CoV2O6 HN acquires extraordinary HER and OER performance with the overpotential of 32.2 and 235.0 mV at the current density of − 10 mA/cm2 and 10 mA/cm2, respectively, which is quite remarkable compared to the recent MXene-based electrocatalysts. Moreover, the overall water splitting device assembled by TS-V2CTx/CoV2O6 HN demonstrates a low cell voltage of 1.358 V at 10 mA/cm2. Thence, this work donates an exciting avenue to overcome the re-stack issue of V2CTx MXene, constructing a superior electrocatalyst with high activity and desirable reaction kinetics.