MoSe2 embedded in (NiCo)Se2 nanosheets to form heterostructure materials for high stability supercapacitors and efficient hydrogen evolution†

Transition metal selenides exhibit significant potential for applications in electrochemical energy storage and catalysis. Addressing the existing limitations that hinder their performance remains a critical challenge. In this study, a 3D self-supporting (NiCo)Se₂/MoSe₂/NF nanostructure, with rough, staggered nanosheet morphology, was developed for dual-functional use in supercapacitors and the hydrogen evolution reaction (HER) during water electrolysis. The (NiCo)Se₂/MoSe₂/NF composite demonstrates exceptional electrochemical performance, achieving a remarkable specific capacitance of 13.563 F cm⁻² at a current density of 3 mA cm⁻². Additionally, the assembled hybrid supercapacitor device exhibits a high energy density of 55.99 Wh kg⁻¹ and a power density of 193.74 W kg⁻¹, while maintaining 92% capacitance retention after 10 000 charge–discharge cycles, highlighting its excellent cycling stability. Moreover, the (NiCo)Se₂/MoSe₂/NF material showcases outstanding HER performance, with a low overpotential of 71.2 mV at a current density of 10 mA cm⁻² and a Tafel slope of 67.3 mV dec⁻¹. The material also demonstrates long-term stability, sustaining its performance for over 100 hours. This study provides a rational design strategy for dual-functional electrode materials, bridging the gap between supercapacitor energy storage and electrolytic water HER applications. The findings underscore the potential of transition metal selenides in energy storage and conversion technologies.