Ultrastretchable MXene–rGO Conductive Double-Network Hydrogels for Multifunctional Wearable Sensing and Energy Harvesting

Abstract Conductive hydrogels, owing to their excellent stretchability, flexibility, and electrical conductivity, have emerged as promising materials for next-generation flexible electronics, wearable sensors, and energy harvesting devices. Herein, we report an ultrastretchable conductive hydrogel based on a polyacrylamide/sodium alginate (PAM/SA) dual-network matrix integrated with a synergistic hybrid conductive framework composed of Ti3C2Tx MXene and reduced graphene oxide (rGO) nanosheets. Benefiting from the complementary interfacial interactions and structural characteristics of the two-dimensional (2D) nanofillers, the resulting MXene/rGO hydrogel exhibits significantly enhanced stretchability and electrical conductivity compared to pristine and single-filler systems. The M15R5 hydrogel-based strain sensor offers a high fracture elongation of 1765%, excellent structural strength of 0.35 MPa, toughness of 3.0 MJ/m3, a high gauge factor (GF = 2.26) over an extensive strain range of 100–700%, a rapid response of approximately 290 ms, and retains excellent durability for beyond 1000 stretch–release cycles. The intrinsic interlayer slip characteristics and high aspect ratios of MXene and rGO, together with their surface-abundant hydrophilic functional groups, create a synergistic, interconnected conductive network that efficiently couples ionic and electronic transport under deformation. Furthermore, the developed hydrogel film was employed as a soft electrode material for triboelectric nanogenerator (TENG) applications in mechanical energy harvesting. The synergistic interaction between ion migration and electron transport significantly enhanced the triboelectric energy conversion performance, delivering a high output voltage of 180 V and a power density of 3.21 W/m2. These results demonstrate the strong potential of the developed hydrogel as a high-performance sensing material and stretchable soft electrode for next-generation energy harvesting systems and flexible electronic devices.