NOx sensor based on semiconductor metal oxide and MXene nanostructures

Nitrogen oxide (NOx) is one of the prominent toxic air pollutants originating from fertilized soils. Considering the excellent properties of semiconducting metal oxides like wide band gap, intrinsic oxygen vacancies, high chemical and thermal stability, they have been investigated in gas sensors to detect toxic gases. Further, MXenes have established as excellent sensing materials in recognition of its tunable surface termination groups, modulating work function and highly conducting nature. Herein, we demonstrate the interfacial engineering of semiconductor metal oxide (SnO2) with MXene (Ti3C2TX) (SnO2/Ti3C2TX) synthesized using hydrothermal method towards the enhancement in the gas sensitivity of low-cost nitrogen oxide (NOx) gas sensor. The structural and morphological characterization of SnO2/Ti3C2TX nanostructures have been performed using X-ray diffraction, field-emission scanning electron microscopy, and Brunauer-Emmett-Teller techniques. Further, SnO2/Ti3C2TX nanostructure have been investigated for gas sensing toward different gases (isopropanol, methane, nitrogen oxide, ammonia, ethanol and acetone) at room temperature and estimated their sensitivity and selectivity. SnO2/Ti3C2TX sensor demonstrated excellent selectivity toward NOx and exhibited high sensing response of 203% with improved response/recovery time of 156/115 s toward NO2 in comparison to pristine SnO2 (56%) and Ti3C2TX (24%)-based sensors, suggesting a promising application prospect in soil released NOx sensing.