A highly sensitive ammonia chemical sensor based on α-Fe₂O₃ nanoellipsoids

Abstract

This paper reports the facile synthesis of α-Fe2O3 nanoellipsoids by a low-temperature hydrothermal process and their effective utilization in the fabrication of a highly sensitive aqueous ammonia chemical sensor by the I–V technique. The as-synthesized α-Fe2O3 nanoellipsoids are characterized in terms of their morphological, structural and optical properties. The detailed structural and optical properties confirm a rhombohedral α-Fe2O3 structure and indirect (1.87 eV) and direct (2.15 eV) band gaps, respectively, for the synthesized nanoellipsoids. The fabricated aqueous ammonia sensor based on nanoellipsoids exhibits a very high and reproducible sensitivity of ∼4.678 µA cm−2 mM−1 and a detection limit of ∼0.04 nM with a correlation coefficient (R) of 0.995 in a short response time (10.0 s). The presented work demonstrates that simply synthesized iron oxide nanostructures can efficiently be used for the fabrication of reliable and reproducible chemical sensors.

Oxo‐Hydroxoferrate K2−xFe4O7−x(OH)x: Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures

“…The remaining bands in the IR spectrum of K 2− x Fe 4 O 7− x (OH) x are probably caused by Fe−O valence vibrations. The bands at 534 cm −1 and at 365 cm −1 and 304 cm −1 can be assigned to [FeO 6 ] octahedra ( T 1u ) and [FeO 4 ] tetrahedra ( C 3v ), respectively, by comparison with the IR spectra of magnetite and hematite ,. The band at 783 cm −1 could be caused by the short Fe−O bond of the bridging tetrahedra (Table S6, Supporting Information).…”

Nanocomposite based flexible ultrasensitive resistive gas sensor for chemical reactions studies

“…The variation of conductivity of metal oxides and conducting polymers has been explored for the detection of ammonia in ppb (parts-per-billion) range. The conventional solid state and conducting polymer sensors suffer from ultralow detection at room temperature1234567891011121314151617181920212223242526. The commercially available conducting polymer sensors require high power consumption since they provide adequate sensitivity only at high temperatures.…”

Investigations on the photoluminescence spectra and its defect-related nature for the ultraviolet transmitting fluoride-containing phosphate-based glasses

“…2(a)-(d) share a common band around 380 nm, which can be assigned to the fluorine-related non-paramagnetic color (FD) centers in the phosphate glasses [23,26,29]. Meanwhile, monitoring at 505 nm, there is a weak but obvious excitation band extending from 415 to 450 nm with a peak maximum near 440 nm (Fig.…”

“…The calculated indirect and direct band gap values of sample A is 4.31 eV and 4.87 eV, respectively, according to Ref [24][25][26]…”