Anchoring MoOx nanodots in N-doped porous carbon via a biomimetic strategy: enhanced supercapacitor performance

Abstract

With the growing demand for high-performance energy storage devices in emerging fields such as electric vehicles and wearable electronics, supercapacitors have emerged as a research focus owing to their high-power density, rapid charge–discharge rates, and exceptional cycling stability. Nevertheless, the widespread application of supercapacitors is constrained by the limited energy density and structural instability of conventional electrode materials. Herein, a biomimetic strategy was proposed to prepare nitrogen-doped activated carbon (NAC) using Shenmu lignite as carbon precursor through a one-step carbonization-activation method, anchoring MoO_x nanoparticles on the NAC matrix, thereby constructing a MoO_x@NAC composite electrode material integrated with synergistic structural and compositional advantages. The composite possesses a remarkable specific surface area (2378 m² g⁻¹), a well-developed hierarchical pore structure, and suitable nitrogen doping. Electrochemical characterization revealed that the MoO_x@NAC electrode delivers an impressive specific capacitance of 40 8F g⁻¹ at a current density of 0.5 A g⁻¹, along with low resistance in a 6 M KOH electrolyte. Furthermore, the assembled symmetric supercapacitor achieves an energy density of 19.6 Wh kg⁻¹ at a power density of 125 W kg⁻¹, underscoring its superior electrochemical performance for advanced energy storage applications. Additionally, the composite demonstrated exceptional cycling stability, retaining 93.6% of its initial capacitance after 10,000 consecutive charge/discharge cycles at a current density of 5 A g⁻¹. This enhanced performance is attributed to the synergistic effect between MoO_x nanoparticles and N-doped porous carbon. Specifically, the nitrogen and oxygen functional groups improve electrolyte wettability and reduce internal resistance, while the reversible redox reactions from Mo species and nitrogen-containing groups provide extra pseudo-capacitance and enrich active sites. This work presents a promising biomimetic strategy for developing high-performance carbon-based electrodes, offering a promising route for the value-added utilization of lignite-derived activated carbon in industrial supercapacitors.