Hierarchically Engineered NiSnSe₂@r-GO@Ni-MOF Composite as a Bifunctional Electrode for High-Performance Supercapacitors and Hydrogen Evolution Reaction

Developing multifunctional electrode materials that integrate high energy storage capacity with catalytic activity is essential for next-generation energy systems. Herein, a hierarchically engineered NiSnSe₂@r-GO@Ni-MOF composite was synthesized by the use of a two-step hydrothermal process, combining the high conductivity of r-GO, the porous framework of Ni-MOF, and the redox activity of NiSnSe₂. Structural and morphological investigations (SEM, XRD, Raman, XPS, and BET–BJH) confirmed the formation of a well-integrated mesoporous architecture with a large available electroactive sites and effective electron–ion transport. Electrochemical evaluation exhibited a high specific capacity of 1297.8 C g⁻¹. The assembled asymmetric device (NiSnSe₂@r-GO@Ni-MOF//AC) achieved an energy density of 44.8 Wh kg⁻¹ and a power density of 1120 W kg⁻¹, with 90% capacity retention over 7,000 cycles. Additionally, the composite exhibited excellent HER response and delivered a low overpotential of 49 mV and a Tafel slope of 52 mV dec⁻¹. The boosted bifunctional enactment is accredited to strong interfacial coupling and stabilizes the electrode structure, which highlights a scalable strategy for designing efficient multifunctional heterostructure to overcome the energy crisis in the present era.