Self-powered sensing platform for monitoring uric acid in sweat using cobalt nanocrystal-graphene quantum dot-Ti 3 C 2 T X monolithic film electrode with excellent supercapacitor and sensing behavior.

The synthesis of cobalt nanocrystal-graphene quantum dot-Ti 3 C 2 T X monolithic film electrode (Co-GQD-Ti 3 C 2 T X ) is reported via self-assembly of Ti 3 C 2 T X nanosheets induced by protonated arginine-functionalized graphene quantum dot and subsequent reduction of cobalt (III). The resulting Co-GQD-Ti 3 C 2 T X shows good monolithic architecture, mechanical property, dispersibility and conductivity. The structure achieves excellent supercapacitor and sensing behavior. The self-charging supercapacitor produced by printing viscous Co-GQD-Ti 3 C 2 T X hydrogel on the back of flexible solar cell surface provides high specific capacitance (296 F g -1 at 1 A g -1 ), high-rate capacity (153 F g -1 at 20 A g -1 ), capacity retention (98.1% over 10,000-cycle) and energy density (29.6 W h kg -1 at 299.9 W kg -1 ). The electrochemical chip produced by printing Co-GQD-Ti 3 C 2 T X hydrogel on paper exhibits sensitive electrochemical response towards uric acid. The increase of uric acid between 0.01 and 800 μM causes a linear increase in differential pulse voltammetry signal with a detection limit of 0.0032 μM. The self-powered sensing platform integrating self-charging supercapacitor, electrochemical chip and micro electrochemical workstation was contentedly applied to monitoring uric acid in sweats and shows one broad application prospect in wearable electronic health monitoring device.