Interface-stabilized phosphorene/bismuthene heterostructures for freeze-tolerant micro-supercapacitors and integrated sensing
Black phosphorus (BP)-based micro-supercapacitors (MSCs) are promising for wearable electronics but suffer from intrinsic instability and sluggish electron kinetics. Here, we report a two-dimensional phosphorene/bismuthene (2D BP/Bi) heterojunction fabricated via liquid nitrogen-assisted exfoliation and mask-assisted filtration, serving as a robust bifunctional electrode for integrated flexible energy-sensing systems. The heterostructure suppresses nanosheet restacking and enhances interfacial stability through strong P–O–Bi covalent bonding and interfacial synergy. Bismuthene incorporation constructs high-speed electron transport channels, facilitating ion diffusion and charge transfer. The optimized BP/Bi (3:1) electrode achieves a high areal capacitance of 7.6 mF·cm−2 (1.6-fold enhancement over pure BP) and ultra-long lifespan with 92.1% retention after 30,000 cycles. By tailoring the gel electrolyte with DMSO, the device exhibits remarkable freeze-tolerance, maintaining 70% capacitance at −35 °C. An all-flexible integrated system combining the MSC with a pressure sensor using graphene current collectors enables continuous, self-sustained physiological monitoring. This work offers critical insights into interface engineering for high-performance BP-based MSCs and paves the way for extreme-environment wearable applications.