Synergistic engineering of heterointerfaces and defects in N, P-codoped carbon-encapsulated MnSe/NiSe₂ heterostructure for efficient alkaline hydrogen evolution and high-performance flexible supercapacitors

This study addresses the critical challenges of insufficient active sites, sluggish kinetics, and poor conductivity in transition metal selenides for HER and supercapacitors by proposing a multi-strategy synergistic optimization approach. Integrating defect engineering (Se vacancies), heterointerface construction (MnSe/NiSe₂), and heteroatom doping, the synthesized MnSe_1-x-NiSe_2-x/NPC (NPC stands for N, P-codoped carbon) demonstrates superior alkaline HER activity (72.5 and 111.6 mV at 10/100 mA cm⁻¹) and high-energy-density supercapacitor performance (71.8 Wh kg⁻¹ at 0.799 kW kg⁻¹). Mechanistic insights from synchrotron XANES, in situ spectroscopy, and DFT calculations elucidate the interfacial electron transfer pathways, dynamic water dissociation behavior during HER, reversible phase transition mechanisms during energy storage, and the optimization of OH⁻/H* adsorption energy via d-orbital hybridization. This work offers a novel design strategy for the simultaneous synthesis of selenium vacancies and heterointerfaces, offering important insights for electrocatalytic and energy storage systems.