Mesoporous MXene/ZnO nanorod hybrids of high surface area for UV-activated NO2 gas sensing in ppb-level

Here, a kind of novel Ti3C2Tx MXene/ZnO nanorod hybrids was reported for optoelectronic NO2 sensors with high response, high sensing rate, sub-ppb detecting limit and superior reproducibility and reversibility. A facile anchored growth method was developed to obtain mesostructured Ti3C2Tx MXene/ZnO nanorod hybrids with a surface area of 146.8 m(2)/g. The sensor based on MXene/ZnO nanorod hybrids demonstrated greatly enhanced optoelectmnic and gas-sensing performance to ppb-leveled NO2 upon UV illumination, in comparison with pure ZnO nanorods. The sensing responses to 5-200 ppb NO2 ranged from 21% to 346% at ambient temperatures, and the response time was 17 s and the recovery time was 24 s (to 50 ppb NO2). Moreover, the mesoporous hybrids exhibited the features of superior reversibility, sub-ppb detection limit (down to 0.2 ppb) and high selectivity to NO2. The extraordinary UV-activated NO2-sensing property was ascribed to the hierarchical mesostructure in addition to the effective photocarrier separation rendered by the highly photoconductive Ti3C2Tx MXene. This work demonstrates that rationally designed MXene-metal oxide hybrid sensitive materials are promising candidates for high-performance UV-activated NO2 sensor operated at ambient temperature.

Automated summary

The novel Ti3C2Tx MXene/ZnO nanorod hybrids demonstrated high response, sensing rate, sub-ppb detecting limit, reproducibility, and reversibility for optoelectronic NO2 sensors. By introducing mesostructured Ti3C2Tx MXene/ZnO nanorod hybrids, the sensor showed greatly enhanced optoelectronic and gas-sensing performance to ppb-leveled NO2 under UV illumination, with superior reversibility, sub-ppb detection limit, and high selectivity to NO2. The UV-activated NO2-sensing property was attributed to the hierarchical mesostructure and effective photogenerated carrier separation of Ti3C2Tx MXene, suggesting the promising application of MXene-metal oxide hybrids for high-performance UV-activated NO2 sensors at ambient temperature.