Au/α-Fe₂O₃/Ti₃C₂T_x MXene Nanosheet Heterojunctions for High-Performance NH₃ Gas Detection at Room Temperature

Abstract

The exploitation of RT sensors with ultra-great sensitivity and unique ammonia (NH3) gas selectivity is still a major scientific task in the field of gas sensing. In the article, a pristine α-Fe2O3 spindle was fabricated by applying the Fe-MIL(88) as the precursor and the sample was smoothly immobilized on the appearance of Ti3C2T x MXene nanosheets through a simple solvothermal reaction, and subsequent gold nanoparticles (Au NPs) were decorated on the α-Fe2O3/Ti3C2T x MXene hybrid material through the in situ reduction process. Gas-sensing measurements presented that the sensor based on the Au/α-Fe2O3/Ti3C2T x MXene nanocomposite exhibited a brilliant NH3 sensing behavior, and the response value of the sensor to NH3 (1 ppm) reached 16.9% at RT under a relative humidity of 25.7%. Moreover, the designed sensor indicated a response/recovery time as low as 3/2 s and good stability. The potential gas sensing mechanism on account of the hybrid structure was discussed combined with the semiconductor depletion layer model and the synergistic effect of the Au/α-Fe2O3/Ti3C2T x MXene ternary heterojunction and Schottky contact theory. Meanwhile, the adsorption effect of NH3 gas was verified by density functional theory calculation. This research is supposed to offer a reliable tactic for large-scale manufacturing of cost-effective, portable, and highly sensitive RT gas sensors.

MXene-Based Chemo-Sensors and Other Sensing Devices

“…The Au/α-Fe 2 O 3 /Ti 3 C 2 T x MXene sensor displayed an excellent NH 3 sensing performance, and its response value to NH 3 (1 ppm) reached 16.9% at RT. Compared to other sensors (based on pure MXene or metal oxides), the obtained sensor had better sensitivity and response/recovery times [149].…”

Room-temperature chemiresistive ammonia sensors based on 2D MXenes and their hybrids: recent developments and future prospects

“…The reported sensor response of this composite was 67% at 1 ppm LOD, which was quite efficient. 62–76 TiO 2 was synthesized using an in situ route on the surface and inner layer of MXene to create a MXene–TiO 2 junction, by Hou et al 73 A response value of 56.9% towards 100 ppm NH 3 at ambient temperature was obtained from the Ti 3 C 2 T x –TiO 2 –CuO composite known as TTC-1, as shown in Fig. 4(h).…”

Room Temperature Chemiresistive Gas Sensors Based on 2D MXenes

“…Moreover, Au, which has a good catalytic activity, has a promising effect on the adsorption and dissociation of oxygen and NH 3 gases from the surface of gas sensors. Based on DFT studies, the adsorption energy of NH 3 on nanocomposites (−8.31 eV) was much larger than that other gases, reflecting the good selectivity of the sensor to NH 3 gas [129].…”