Quasicrystal Nanosheet/α-Fe 2 O 3 Heterostructure-Based Low Power NO 2 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 Al70 Co10 Fe5 Ni10 Cu5 have emerged as a promising material for gas sensors due to their excellent catalytic and electronic properties. Herein, we demonstrate highly sensitive and selective NO2 sensors developed by low-cost and scalable fabrication techniques using 2D QC nanosheets and α-Fe2 O3 nanoparticles. The sensitivity (Δ R / R %) of the optimal amount of 2D QC nanosheet-loaded α-Fe2 O3 sensor was 32%, which is significantly larger about 3.5 times than bare α-Fe2 O3 sensors for 1 ppm of NO2 at 150 °C operating temperature. The sensors exhibited p-type conduction, and resistance was reduced when exposed to NO2 , an oxidizing gas. The enhanced sensing characteristics are a result of the formation of nanoheterojunctions between 2D QC and α-Fe2 O3 , which improved the charge transport and provided a large sensing signal. In addition, the heterojunction sensor demonstrated excellent NO2 selectivity over other oxidizing and reducing gases. Furthermore, density functional theory calculation examines the adsorption energy and charge transfer between NO2 molecules on the α-Fe2 O3 (110) and QC/α-Fe2 O3 (110) heterostructure surfaces, which coincides well with the experimental results.