MXene-based conductive hydrogels with toughness and self-healing enhancement by metal coordination for flexible electronic devices

MXene-based conductive hydrogels have emerged as a new type of soft materials in flexible electronics. Herein, metal coordination is introduced into MXene-based conductive hydrogels to synchronously enhance the mechanical and self-healing properties. MXene-based conductive hydrogels are made up of polyacrylic acid (PAA), sium carboxymethyl cellulose (SCMC), Ti₃C₂T_X and metal ions (Ni²⁺, Al³⁺ or Sn⁴⁺). PAA/SCMC/Ti₃C₂T_X/Sn⁴⁺ hydrogel is found to have excellent mechanical (stress: 122 kPa; strain: 1688 %; toughness: 0.95 ± 0.12 MJ m⁻³) and self-healing (self-healing efficiency: 99.27 % (conductivity); 81.16 % (stress); and 83.13 % (strain)) properties due to the metal coordination and H-bonding. The hydrogel has also good conductivity of 0.82 S m⁻¹ and adhesion of 38.94 kPa. The flexible sensors based on this hydrogel can efficiently detect human motions, electromyography (EMG), electrocardiography (ECG) and handwriting signals. Furthermore, a supercapacitor assembled from this hydrogel has a high specific capacitance of 118.66 F g⁻¹ and good stability (15000 charge-discharge cycles). This work provides an effective strategy for exploiting mechanically tough and self-healing MXene-based conductive hydrogels with prospective applications in flexible electronics.