Xiong Yu,Hao Li,Min Li,Xiaoyan Wen,Shuo Deng,Sisi Liu,Ming-Yu Li,Haifei Lu
MXenes with numerous superior properties have great potential for portable and conformal humidity sensing, which can meet the ever-increasing requirements for noncontact medical diagnosis, noninvasive epidermal detection, and environmental monitoring. Due to the ambiguous mechanism, the absence of an efficient approach for improving the sensitivity and selectivity remains a big obstacle for realization of MXene-based humidity sensing. In this work, the evolution of humidity sensing mechanisms of few-layered Nb2CTx nanosheets before and after self-oxidation in aqueous solutions are clarified depending on a systematic comparison. The evolution of structure and chemical bonds in few-layered Nb2CTx nanosheets after different incubation durations has been investigated to understand the in situ self-oxidation process and establish the relationship between the oxidation degree and humidity sensing performance. Meanwhile, the humidity sensing mechanism of sensors for different few-layered Nb2CTx nanosheets has been also clarified, and the humidity sensitivity has been optimized to −2.3 × 104 with a relative humidity of 53%. Compared with the sensor prepared from as-prepared few-layered Nb2CTx nanosheets, the humidity sensing selectivity from oxidized few-layered Nb2CTx nanosheets has been improved, contributed to by the transformation of the sensing mechanism from electronic conduction to ionic conduction. Finally, the oxidized few-layered Nb2CTx nanosheets have been prepared on a PI substrate to demonstrate its application in a flexible humidity sensor, providing a facile solution for ultrasensitive wearable gas sensing.
Combining advanced energy-generation technologies with sensors to develop self-powered sensing shows great potential in intelligent electronics, but sluggish response kinetics and low output are the main obstacles. Herein, we design a hyaluronic acid (HA)-induced crumpling of Nb 2 CT x nanosheet to construct hydrogen bond conduction network, and develop it for fast humidity sensing based on primary battery . The in-situ formation of organic/inorganic hybrid interphase with crumpling structure by electrostatic flocculation is capable to provide abundant adsorption sites and accelerate proton (H + ) transport. Benefited from these, the Nb 2 CT x /HA primary battery-based humidity sensor (PBHS) not only exhibits an outstanding response and recovery speed (15.1 s and 3.4 s at 72.0 % relative humidity (RH)), high response (0.7 V), low hysteresis (3.6 % RH), but also can be also used as a nanogenerator with a power of 0.96 μW and sustainable voltage output for 12 h. Furthermore, the multifunctional applications are demonstrated in medical assisted monitoring, health care, intelligent sensing, and green-energy generation. This work offers a new insight into PBHS design and the development of high-performance power-generation humidity sensor.
危险品化学品经营许可证（带存储）