Electron-delocalization-engineered hydrangea-like BNC@NiO/NiSe2 triple heterojunctions towards synergistic energy storage and hydrogen evolution

Due to the urgent demand for clean energy transitions, the development of bifunctional electrode materials with efficient energy storage and conversion capabilities has become a priority. This paper presents a novel nanohydrangea-like BNC@NiO/NiSe 2 composite with triple-phase heterointerfaces fabricated using boric acid-modified ZIF-8-derived B/N co-doped porous carbon (BNC) and a controlled selenization strategy. The heterogeneous structural design facilitated interfacial electron delocalization and constructed a three-phase built-in electric field, optimizing electron transport paths and active site distribution, and improving the charge transfer efficiency. The 3D porous BNC matrix effectively prevented NiO/NiSe 2 nanosheet aggregation, whereas interfacial charge redistribution significantly enhanced the conductivity and reaction kinetics. As a supercapacitor electrode, BNC@NiO/NiSe 2 delivered a high specific capacitance of 862 F g −1 at 1 A g −1 and maintained 416 F g −1 at 20 A g −1 (retaining 70.8 % capacity after 2000 cycles). For the hydrogen evolution reaction, BNC@NiO/NiSe 2 achieved a low overpotential ( η 10 ) of 126 mV with a Tafel slope of 74 mV dec −1 , demonstrating 100 h stability. Density functional theory (DFT) calculations revealed that heterogeneous interfaces promoted electron delocalization and facilitated the formation of directional built-in electric fields through electron density differences, synergistically optimizing the redox kinetics and charge transfer efficiency. This study provides new insights into the design and use of heterojunction materials as high-performance, stable bifunctional electrodes.