Low-Humidity-Dependent and Stretchable Moisture-Electricity Generator Based on Ti₃C₂T_<i>x</i> MXene-Loaded Cotton and Hydrogel Bilayer for Green Power Harvesting and Wearable Electronics

Moisture-enabled electricity generator (MEG) technology converts energy from the environment into green electricity by exploiting the interaction between atmospheric moisture and hydrophilic materials and has the advantages of a simple device structure, small geographical and temporal constraints, and environmental friendliness; therefore, it has great application value in serving as a power source for portable electronic devices. However, the high output performance of most MEG devices is dependent on high ambient relative humidity (RH), and current MEG technologies tend to be poorly flexible and lack wearability, which severely pose a barrier to their practical utilization. Here, we have developed a high-performance bilayer MEG with exceptional environmental adaptability and stretchability. By rationally combining Ti₃C₂T_<i>x</i> MXene-loaded cotton knitted fabrics (MC) and a stretchable double-network ionic hydrogel (IH) to form the MXene/cotton-ionic hydrogel MEG (MCIH-MEG), the MCIH-MEG with 230% stretchable capacity can continuously provide an open-circuit voltage (<i>V</i>_oc) of 0.5 V and a short-circuit current (<i>I</i>_sc) of 50 μA, which stem from the continuous water evaporation within the device and fast capillary water flow on MXene nanosheets, as well as redox reactions at the electrodes, which can achieve good electrical performance across a wide range of temperatures (0-80 °C) and RH levels (20-95%). Due to its flexibility, stable electrical output, and sensitivity to external stimuli, MCIH-MEG can be employed in the fabrication of self-powered sensors to detect simple weight changes or even complex gesture changes and in the construction of self-powered smart masks for respiratory monitoring.