Dual-Function 2D Vanadium Disulfide for Energy Storage and Biosensing: Toward Self-Powered Neurotransmitter Detection

Wearable biosensors are revolutionizing health monitoring, yet their wider adoption remains constrained by the lack of compact and reliable power sources for continuous operation. In this work, vanadium disulfide (VS2) is employed as a multifunctional material, enabling both energy generation and electrochemical biosensing within a unified platform. 1T-phase VS2 nanosheets are hydrothermally synthesized and implemented as: (i) cathode material in a 3D-printed aqueous zinc-ion battery (AZIB) and (ii) gate electrode in an organic electrochemical transistor (OECT) for neurotransmitter detection. The VS2 cathode is printed using direct ink writing (DIW) into a woodpile structure and encapsulated with styrene-ethylene-butylene-styrene (SEBS) gel, delivering 161.3 mAh g-1 at 0.1 A g-1 and retaining 85% capacity after 90 cycles. This Zn-VS2 battery provides a stable discharge of 147 hours (~6 days) at 30 µA, a typical operating current for OECT, matching the demands of wearable biosensing. Simultaneously, the catalytic properties of 1T-phase VS2 are exploited to fabricate a gate for redox-based detection of neurotransmitters, achieving detection limits below 200 nм for dopamine and 10 nм for serotonin. This dual functionality of VS2 paves the way for self-powered, integrated biosensing platforms, addressing a major bottleneck in the development of autonomous wearable health monitoring.