Covalent Graphene-Metal-Organic Polyhedra Hybrids: Triboelectric Nanogenerators for Next Generation of Wearable...

The development of stretchable energy-harvesting devices that convert mechanical stimuli into electrical energy is crucial for advancing self-powered electronic skin (e-skin) technologies. Triboelectric nanogenerators (TENGs) show promise but suffer from low stretchability, limited conductivity, and poor mechanical durability. Here, we report a new generation of TENGs designed via the molecular chemistry of metal-organic polyhedra (MOPs) covalently bonded to functionalized 2D nitrogen-doped graphene sheets (NG@MOP). The resulting NG@MOP hybrids, featuring aromatic regions and surface amine groups, link to anionic nickel-based MOPs, [Ni₈(HImDC)₁₂]^8-, through amide bonds. This hybrid exhibits a large surface area, hierarchical micro-mesoporous channels, and structural defects, improving mechanical resilience. Incorporating NG@MOP into a polyurethane matrix produces a highly stretchable, biocompatible film withstanding over 500% strain. The composite delivers excellent triboelectric output, generating 417 V and 10.8 µA at 5 wt % loading. Applied as a wearable e-skin, the device maintains functionality under extreme deformation, demonstrating a strain sensitivity of 13 mV per degree of motion. It efficiently detects subtle body motions such as bending and stretching, showing strong potential for wearable motion sensing and real-time health monitoring.