Au/α-Fe2O3/Ti3C2Tx MXene Nanosheet Heterojunctions for High-Performance NH3 Gas Detection at Room Temperature

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 Ti3C2Tx MXene nanosheets through a simple solvothermal reaction, and subsequent gold nanoparticles (Au NPs) were decorated on the α-Fe2O3/Ti3C2Tx MXene hybrid material through the in situ reduction process. Gas-sensing measurements presented that the sensor based on the Au/α-Fe2O3/Ti3C2Tx 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/Ti3C2Tx 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.