Self-Powered Monitoring of Ammonia Using an MXene/TiO₂/Cellulose Nanofiber Heterojunction-Based Sensor Driven by an Electrospun Triboelectric Nanogenerator

Abstract

Real-time monitoring of harmful gases is of great significance to identify the environmental hazards to people's lives. However, this application scenario requiring low-power consumption, superior sensitivity, portability, and self-driven operation of gas sensors remains a challenge. Herein, an electrospun triboelectric nanogenerator (TENG) is synthesized using highly electronegative and conducting MXene nanofibers (NFs) paired with biodegradable cellulose acetate NFs (CA-NFs) as triboelectric layers, which supports a sufficient power density (∼1361 mW/m 2 @2 MΩ) and shows a self-powered ability to operate the chemiresistive gas sensor fabricated in this work. Further, by using cellulose nanofibers (C-NFs) as a substrate, a new kind of MXene/TiO 2 /C-NFs heterojunction-based sensory component is developed for detection of NH 3 . This sensor exhibits excellent reproducibility, high selectivity, and sensitivity toward NH 3 (1−100 ppm) along with a fast response/recovery time (76 s/62 s) at room temperature. Finally, a monitoring system comprising a TENG-powered sensor, an equivalent circuit, and an LED visualizer has been assembled and successfully demonstrated as a fully self-powered device for NH 3 leakage detection. Thus, this work pushes forward the intelligent gas sensing network self-driven by human motion energy, dispensing the external battery dependence for environment monitoring to reduce the possible health effects.

Gas‐Sensitive Cellulosic Triboelectric Materials for Self‐Powered Ammonia Sensing

“…This is due to the limited ammonia‐sensitive functional groups on the surface of Ti 3 C 2 T x as the cycle time and the number of cycles increase, the reaction of the gas with the surface of the frictional electric material gradually decreases, and eventually, the sensitivity of the sensor should gradually decrease with the surface reaction with the gas (Figure S7 , Supporting Information). [ 33 ] The response values shown in Figure 5j indicate that the PFOTES‐Ti 3 C 2 T x ‐CNF has great sensitivity to ammonia gas at the same gas concentrations, which is considered for the formation of more adsorption sites on the PFOTES‐Ti 3 C 2 T x ‐CNF film. [ 34 ] The 2D structure of Ti 3 C 2 T x gives it a higher specific surface area and can adsorb many end‐joining groups on the surface.…”

Emergence of MXene–Polymer Hybrid Nanocomposites as High‐Performance Next‐Generation Chemiresistors for Efficient Air Quality Monitoring

“…[200] Furthermore, the inclusion of nanotriboelectric generators in chemiresistor circuitry results in their selfoperation without using any external power source. For instance, Sardana et al [201] reported selfdriven room tem perature ammonia detecting chemiresistor based on MXene/ TiO 2 /Cellulose nanofiber heterojunction driven using electro spunbased triboelectric nanogenerators. The chemiresistor demonstrated high sensitivity, selectivity and reproducibility with rapid response and recovery within 76 and 32 s. The work opened a new window to architect intelligent and realtime gas leakage detection by selfdriven and sustainable chemiresistor powered by human motion.…”

Integrated Self‐Powered Sensors Based on 2D Material Devices

“…The gas sensor exhibited great reproducibility and high selectivity. [ 128 ] Figure a depicts the possible mechanism of MXene/TiO 2 /C‐NFs heterojunction‐based sensor and the electron transfer process between MXene and TiO 2 . The electrons of n‐type TiO 2 gradually migrate into the conduction band of MXene until the Fermi levels of the two materials flatten.…”

“…Reproduced with permission. [ 128 ] Copyright 2022, American Chemical Society. b) Fabrication process and schematic structure of a Si/n‐CdS NWs heterostructure near‐infrared photodetector.…”