Self-powered sensing platform for monitoring uric acid in sweat using cobalt nanocrystal-graphene quantum dot-TiCT monolithic film electrode with excellent supercapacitor and sensing behavior.

The synthesis of cobalt nanocrystal-graphene quantum dot-TiCT monolithic film electrode (Co-GQD-TiCT) is reported via self-assembly of TiCT nanosheets induced by protonated arginine-functionalized graphene quantum dot and subsequent reduction of cobalt (III). The resulting Co-GQD-TiCT 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-TiCT hydrogel on the back of flexible solar cell surface provides high specific capacitance (296 F g at 1 A g), high-rate capacity (153 F g at 20 A g), capacity retention (98.1% over 10,000-cycle) and energy density (29.6 W h kg at 299.9 W kg). The electrochemical chip produced by printing Co-GQD-TiCT 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.