Quasicrystal Nanosheet/α-Fe<sub>2</sub>O<sub>3</sub> Heterostructure-Based Low Power NO<sub>2</sub> Sensors: Experimental and DFT Studies
Sumit Kumar, Mirabbos Hojamberdiev, Anyesha Chakraborty, Rahul Mitra, Rajneesh Chaurasiya, Monika Kwoka, Chandra Sekhar Tiwary, Krishanu Biswas, Mahesh Kumar
Abstract
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 Al 70 Co 10 Fe 5 Ni 10 Cu 5 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 2 sensors developed by low-cost and scalable fabrication techniques using 2D QC nanosheets and α-Fe 2 O 3 nanoparticles. The sensitivity (Δ R / R %) of the optimal amount of 2D QC nanosheet-loaded α-Fe 2 O 3 sensor was 32%, which is significantly larger about 3.5 times than bare α-Fe 2 O 3 sensors for 1 ppm of NO 2 at 150 °C operating temperature. The sensors exhibited p-type conduction, and resistance was reduced when exposed to NO 2, an oxidizing gas. The enhanced sensing characteristics are a result of the formation of nanoheterojunctions between 2D QC and α-Fe 2 O 3, which improved the charge transport and provided a large sensing signal. In addition, the heterojunction sensor demonstrated excellent NO 2 selectivity over other oxidizing and reducing gases. Furthermore, density functional theory calculation examines the adsorption energy and charge transfer between NO 2 molecules on the α-Fe 2 O 3 (110) and QC/α-Fe 2 O 3 (110) heterostructure surfaces, which coincides well with the experimental results.