Nanometer-Thick ZnO/SnO₂ Heterostructures Grown on Alumina for H₂S Sensing

Abstract

Designing heterostructure materials at the nanoscale is a well-known method to enhance gas sensing performance. In this study, a mixed solution of zinc chloride and tin (II) chloride dihydrate, dissolved in ethanol solvent, was used as the initial precursor for depositing the sensing layer on alumina substrates using the ultrasonic spray pyrolysis (USP) method. Several ZnO/SnO 2 heterostructures were grown by applying different ratios in the initial precursors. These heterostructures were used as active materials for the sensing of H 2 S gas molecules. The results revealed that an increase in the zinc chloride in the USP precursor alters the H 2 S sensitivity of the sensor. The optimal working temperature was found to be 450 °C. The sensor, containing 5:1 (ZnCl 2 : SnCl 2 ·2H 2 O) ratio in the USP precursor, demonstrates a higher response than the pure SnO 2 (∼95 times) sample and other heterostructures. Later, the selectivity of the ZnO/SnO 2 heterostructures toward 5 ppm NO 2 , 200 ppm methanol, and 100 ppm of CH 4 , acetone, and ethanol was also examined. The gas sensing mechanism of the ZnO/SnO 2 was analyzed and the remarkably enhanced gas-sensing performance was mainly attributed to the heterostructure formation between ZnO and SnO 2 . The synthesized materials were also analyzed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, transmission electron microscopy, and X-ray photoelectron spectra to investigate the material distribution, grain size, and material quality of ZnO/SnO 2 heterostructures.

Melamine Cyanaurate Microrods Decorated with SnO2 Quantum Dots for Photoelectrochemical Applications

“…The peaks at 813 cm −1 and 771 cm −1 are credited to ring-sextant out-of-plane bending vibration [26], the peak at 595 cm −1 is due to ring bending [27], and the peak at 629 cm −1 is due to the side chain in plane C-N bending vibration [28]. The observed bands at 564 and 663 cm −1 are related to the strong antisymmetric Sn-O-Sn and terminal Sn-O modes of vibration in SnO 2 [29]. The characteristic Sn-O-Sn bond is recognized at 640 cm −1 [30].…”

Flexible solar and thermal energy conversion devices: Organic photovoltaics (OPVs), organic thermoelectric generators (OTEGs) and hybrid PV-TEG systems

“…Although development of wearable technology has grown rapidly over the past decade, it is still in its infancy and is confronted by several obstacles towards widespread application. One of the main issues with wearable electronic devices is the lack of a sustainable power source in place of conventional batteries for powering the operating sensors and actuators [43]. Such power sources must overcome the problems associated with traditional batteries such as large size, rigidity, high weight, and limited lifetime [44].…”