Quasicrystal Nanosheet/α-FeO Heterostructure-Based Low Power NO Sensors: Experimental and DFT Studies.

Industrial emissions, environmental monitoring, and medical fields have put forward huge demands for high-performance and low power consumption sensors. Two-dimensional quasicrystal (2D QC) nanosheets of metallic multicomponent AlCoFeNiCu have emerged as a promising material for gas sensors due to their excellent catalytic and electronic properties. Herein, we demonstrate highly sensitive and selective NO sensors developed by low-cost and scalable fabrication techniques using 2D QC nanosheets and α-FeO nanoparticles. The sensitivity (Δ/%) of the optimal amount of 2D QC nanosheet-loaded α-FeO sensor was 32%, which is significantly larger about 3.5 times than bare α-FeO sensors for 1 ppm of NO at 150 °C operating temperature. The sensors exhibited p-type conduction, and resistance was reduced when exposed to NO, an oxidizing gas. The enhanced sensing characteristics are a result of the formation of nanoheterojunctions between 2D QC and α-FeO, which improved the charge transport and provided a large sensing signal. In addition, the heterojunction sensor demonstrated excellent NO selectivity over other oxidizing and reducing gases. Furthermore, density functional theory calculation examines the adsorption energy and charge transfer between NO molecules on the α-FeO(110) and QC/α-FeO(110) heterostructure surfaces, which coincides well with the experimental results.