Highly tough and conductive hydrogel based on defect-patched reduction graphene oxide for high-performance self-powered flexible sensing micro-system

Tough and conductive reduction graphene oxide (rGO)-based hydrogels have broad application prospects in various flexible wearable electronics. However, an often ignored phenomenon was that numerous defective regions were inevitably formed within the basal plane of rGO during synthesis process, deteriorating the physical characteristics as well as overall performances of wearable devices. Herein, a facile and effective defect patching engineering was proposed to heal rGO by carbonized metal-organic frameworks (CMOF). The fixed CMOF at defect regions acted as a bridge to allow electrons to pass quickly and enhance tolerance of rGO to loaded mechanical energy. The resultant optimized hydrogel containing defect-patched rGO flakes not only possesses satisfied mechanical properties (e.g., tensile strength of 195 kPa) and high electrical conductivity (2.42 S/m), but also exhibits reinforced electric output performances when assembled into triboelectric nanogenerator, supercapacitors and sensor devices. More importantly, the sensor with high sensitivity (gauge factor (GF) of 14.68, short response time of 40 ms) was capable of effective distinguishing complex human activities and accurate detecting the temperature fluctuation of skin within narrow range. As proof-of-concept, the as-synthesized all-inone flexible intelligent micro-system, composed of power supply, energy storage and sensing units, had proved the great compatibility and feasibility of wearable electronics in detecting and recognizing human expressions, motion and physiological signals. Our findings proposed a reliable defect patching strategy for large-scale production of defect-free 2D carbonaceous materials, boosting the development of high-performance self-powered sensing micro-system in wearable devices.