Ionic-Liquid-Assisted Synthesis of NiTe/CoTe Heterostructure With Te Vacancies in N, P, and F Co-Doped Hollow Carbon Nanorods for Efficient Alkaline Hydrogen Evolution and High-Performance Flexible Supercapacitors

Low conductivity, slow ion-diffusion, and limited reactive sites are common problems in electrocatalysts and electrode materials. In this study, a complex NiTe–CoTe heterojunction with abundant Te vacancies embedded in N, P, and F co-doped hollow carbon nanorods (NiTe_1−x–CoTe_1−x/NPFC) was fabricated via a simple ionic liquid-assisted hydrothermal method and calcination. NiTe_1−x–CoTe_1−x/NPFC shows excellent activity (80.1 and 108.4 mV overpotentials at 10/100 mA cm⁻¹) for the hydrogen evolution reaction in 1.0 M KOH solution. Moreover, NiTe_1−x–CoTe_1−x/NPFC exhibits an excellent energy density of 57.9 Wh kg⁻¹ at an extremely high power density of 15.90 kW kg⁻¹ in a flexible solid-state supercapacitor, revealing its outstanding performance. 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. Overall, this study will facilitate the design of telluride heterojunctions with tellurium-rich vacancies as well as N, P, and F doped carbon composites, which can be applied to other electrode materials and electrocatalysts.