Fast charge transport motivated by tunable Mo₂C/Mo₂N high-quality heterointerface for superior pseudocapacitive storage

The development of potential transition-metal carbide/nitride heterojunctions is hindered by overall understanding and precise modulation for heterointerface effects. Herein, we demonstrate that Mo₂C/Mo₂N heterojunction with the precisely regulated high-quality interface can achieve marvelous rate performance and energy output via enlarging the interface-effect range and maximizing “accelerated charge” amount. The heterointerface mechanism improving properties is synergistically revealed from kinetics and thermodynamics perspectives. Kinetics analysis confirms that the self-built electric field affords a robust force to drive rapid interface electrons/ions migration. The small adsorption energy, high density of states and quite low diffusion barrier thermodynamically enhance the electrochemical reaction dynamics on heterointerface. Consequently, the almost optimal performance of ultrahigh capacitance retention (85.6% even at 10 A g⁻¹) and pronounced energy output (96.4 Wh kg⁻¹) in hybrid-supercapacitors than other Mo₂C/Mo₂N-based materials is presented. This work gives new insight into the energy storage mechanism of heterojunction and guides the design of advanced electrodes.