Edge-Site-Enriched Ti3C2Tx MXene/MoS2 Nanosheet Heterostructures for Self-Powered Breath and Environmental Monitoring

Abstract

The architecture of an ammonia (NH3) monitoring system that serves as a versatile tool for real-time breath sampling and environmental gas sensing is proposed herein. By means of first-principles density functional theory (DFT) simulations, an edge-site-enriched MXene/MoS2 nanosheet heterostructure is systematically investigated and used both as a sensing material and an active layer of a hybrid tribo-/piezonanogenerator (H-TPNG). This allows combining the potential of gas sensing and energy harvesting into a single device, with benefits of self-powered monitoring of NH3. The high selectivity, reversibility, and sensitivity (47%@10 ppm) of the prepared sensor to target NH3 gas are revealed, resulting from the increased adsorption sites and improved charge transfer at the edge sites observed from DFT studies. On the other hand, the mechanical tapping and bending motions of the H-TPNG effectively stimulate the instantaneous triboelectric and piezoelectric power densities of 1604.44 and 15.62 mW/cm2, respectively. Additionally, the nanofibrous morphology of the H-TPNG introduced by the electrospinning technique provides great flexibility and conformability to the device for large-area integration of body parts. Finally, a self-powered NH3 monitoring system is assembled which demonstrates the autonomous operation of a sensor for breath analysis and environmental monitoring and could pave the way for the advancement of wearable monitors for healthcare applications.