Mycelium network inspired PVDF-HFP/g-C₃N₄/Mo₂AlB₂ piezoelectric fibrous mat-based hybrid nanogenerator for underwater wireless electro-mechanical energy harvesting and battery-free aquatic rescue systems

Abstract

Recent breakthroughs in technological advancements have enabled advanced underwater exploration and monitoring. However, submerged systems still face significant issues related to energy supply, communication reliability, and sensing precision. Addressing these challenges, we report a heterojunction engineered piezoelectric poly(vinylidene fluoride-co-hexafluoropropylene)/ graphitic carbon nitride/ molybdenum aluminium boride (PVDF-HFP/g-C3N4/Mo2AlB2)nanofibrous (PgCM-NF) mat assisted highly sensitive hybrid nanogenerator for aquatic wireless electro-mechanical energy harvesting applications and underwater wireless rescue operations. The working mechanism of the hybrid nanogenerator relies on the piezo-tribo combined effects. For battery-free underwater wireless communication, the idea of Maxwell’s displacement current has been implemented. Besides this, the g-C3N4/Mo2AlB2 heterojunction inside the PgCM-NF leads to the augmentation of the built-in electric field compared to g-C3N4, resulting in the high d33 value of 47.8 pC/N and 85.5% β-crystalline phase formation with bead-free and Mycelium network-like morphologies. Under 5 N force, the self-polarized piezoelectric mat enhances the surface charge of the hybrid device, resulting in the output voltage of 168.2 V and a power density of 0.32 W/m2. A systematic study confirms the successful electro-mechanical energy conversion ability of the device in different underwater environments, including salinity and turbidity conditions. To confirm the feasibility of underwater wireless communication, blue LEDs are illuminated using displacement current-assisted wireless transmitting signals. Additionally, an auto-powered underwater wireless rescue system is demonstrated using the hybrid device as a Morse code generator and Maxwell’s displacement current assisted wireless communication, demonstrating its potential utility in real-time tracking and surveillance applications.