MoS₂/WO₃Nanosheets for Detection of Ammonia

Abstract

This article demonstrates the use of a p-MoS2/n-WO3 heterojunctions based ultra sensitive and selective chemiresistive ammonia sensor that operates at 200◦ C. Surprisingly, the composite based sensor exhibited significant enhancement in ammonia sensing as compared to MoS2 (p-type) and WO3 (n-type) counterparts. The device also displayed excellent response-recovery features over a wider range of ammonia concentration together with superior selective nature toward ammonia as compared acetone, ethanol, methanol, isopropanol, formaldehyde, benzene, and hydrogen sulfide. Empowered by better signal-to-noise ratio, ammonia detection down to 1 ppm has become possible and can be further improved with the use of serpentine type electrodes. The device has shown a relative response of 207% for 200 ppm of ammonia with response and recovery times of 80 and 70 s, respectively. Moreover, these experimental results were further supplemented by density functional theory (DFT) simulation that were used to understand the adsorption kinetics and the sensing mechanism. A significant amount of charge transfer (0.082 e) between the adsorbed ammonia molecule and the MoS2/WO3 surface has been predicted by Bader analysis. Analysis also revealed a large negative adsorption energy ≈3.86 eV (373 kJ/mol) per ammonia molecule, implying the adsorption process to be chemisorption in nature. The band structure analysis further confirmed that ammonia adsorption on MoS2/WO3 is accompanied by an increase in band gap (by ≈ 96 meV). The present work illustrates the potential use of composite based heterostructures for monitoring ammonia gas in real fields.

MoS2/CeO2 Based Composite for Ammonia Sensing

“…(1) here, ρ referes to liquid density (g/mL), T, Vs and M refer to working temperature in K, evaporated liquid volume in µL and molecular weight of liquid in g/mol, respectively. V and C represent the test chamber volume (L) and concentration of different gases in ppm, respectively [3]. Further, Mott-Schottky (MS) plots were acquired with an electrochemical workstation (M204 Autolab, The Netherlands).…”

“…Their, 2D structure and hence large surface to volume ratio accompanied with semiconducting nature facilitate their potential use for gas sensing applications. Though, gas sensing using MoS2, WS2 and their composites has been demonstrated [3,4] but in a few cases, delayed recovery arising due to thick layered structure has been reported [5,6]. Therefore, to overcome some of these problems various other methodologies, for instance, grain size control, doping and making composite with other materials have been used.…”

“…Among these methods, composite formation has proven to be successful as it provides enhanced device performance and better selectivity over the individual host IOP Publishing doi:10.1088/1757-899X/1225/1/012059 2 material. For instance, MoS2/SnO2 n-n heterojunctions [4,7], MoS2/multiwalled carbon nanotubes hybrids [8], MoS2/WO3 composite [3] and MoS2/Co3O4 composite [9] were found to have enhanced ammonia sensing performance. Therefore, a composite based approach may offer solution to the problems faced by sensor made from either MOS and TMDCs alone.…”

Highly Efficient MoS2/CsxWO3 Nanocomposite Hydrogen Gas Sensors

“…Therefore, combining MoS 2 with unique material is important for achieving an enhanced sensing performance. For instance, WO 3 /MoS 2 composites have been developed, and the nanocomposite exhibits excellent ammonia and hydrogen sulfide sensing properties (Singh et al, 2020, Singh et al, 2021. However, these sensor devices function only at temperatures higher than 200 °C. Besides, most of the previously developed hydrogen gas sensor exhibited low sensor response.…”

A novel study of tungsten oxide nanocrystallites as fuel additive for diesel oil

“…Because of the large surface area, flexible gap, high chemical stability, nontoxicity, cheapness, abundance, high photocatalytic activity and corrosion resistance properties of WO 3 nano-semiconductors at nano level, numerous articles have been published. It is evident that nano-semiconductors are now being used in different fields due to its unlimited applications include solar cells [10,11], gas sensors [12][13][14], drug delivery [15], fuel additives (current work), dye degradation [16], water treatment [17][18][19], Li-ion batteries [20,21], fuel cells [22,23], supercapacitors [24], corrosion [25], dye sensitized solar cells [26], antimicrobial activity [27], fire packing and resistance [28], cancer cell treatment [29], paint and coating industry [30], bone tissue engineering [31], nano-printing [32], etc. On the basis of these facts, this is being expected that various products based on aforementioned properties will be commercially available soon.…”