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

Abstract

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.