A DFT study on the Ag-decorated ZnO graphene-like nanosheet as a chemical sensor for ethanol: Explaining the experimental observations
Introduction
Nowadays, the use of metal oxide-based chemical sensors has fascinated much attention due to their easy production, simple measuring electronics, compact size, and low cost [1], [2], [3], [4], [5]. The ZnO is one of the most prevalent sensing materials due to its excellent photonic properties, large excitation energy, and superior electronic properties [6], [7], [8], [9]. Formerly, ZnO nanostructures with different morphologies have been produced, such as nanosheets, nanobelts, nanotubes, nanowires, etc. [10], [11], [12], [13], [14]. However, the structure and morphology may impact the sensing properties of nanostructures [15], [16], [17], [18], [19]. Different kinds of ZnO nanostructures have been previously applied for gas sensing purposes [20], [21], [22], [23], [24]. It has been indicated that ZnO nanosheets have promising sensing properties owing to their larger surface to volume ratio, superior electronic properties, and extra active places [25].
However, pristine ZnO nanosheets have a relatively weak interaction with various molecules. To resolve the problem, some methods are accessible such as structural defect creation, chemical functionalization, impurity atom doping or decoration, etc. [26], [27]. Decorating noble metals on the surface of metal oxides is a promising technique to change their sensing performances. Wang et al. have shown that the sensing performance of the three-dimensional ZnO nanomaterial upsurges more than three times by decorating the Au atoms [28]. The Au-decorated ZnO nanomaterials could effectively sense acetone at low concentrations [29]. Gu et al. have synthesized Pt-decorated ZnO nanosheets, indicating that it is a suitable sensor for the detection of chlorobenzene gas [30].
Highly sensitive ethanol sensors are required in numerous fields, including on-site monitoring of drunken driving, safety testing of food packaging, real-time control of fermentation processes, and so on [31]. A ZnO nanorod sensor has been suggested which might sense ethanol at sub-ppm level [32]. Mesoporous SnO2 nanostructures have been synthesized, indicating high sensitivity to ethanol with a 50-ppb detection limit [33]. More sensitive ethanol sensors are needed for further use at low concentration detection. Earlier works exposed ZnO nanosheets show highly sensitivity and meaningfully long-term stability [34]. Recently, Meng et al. have synthesized Ag-decorated ZnO nanosheet (Ag@ZnO nanosheet), indicating that it is sensitive to ethanol with a 1 ppb detection limit [35]. Here, we use density functional theory calculations to clarify the experimental observations. To this aim, we investigated the adsorption of the ethanol gas on the pristine ZnO nanosheet and Ag@ZnO nanosheet, and compared the results with the experimental data. We introduced a theoretical methodology which can reproduce the experimental results.
Section snippets
Computational methods
The GAMESS software program was used to conduct the computations [36]. GaussSum was employed for obtaining the diagrams of density of states (DOS) [37]. B3LYP functional has been proved to provide the most precise results for molecular characteristics of different nanostructures [38]. The problem associated with DFT functionals is estimating the dispersion interaction. Consequently, we utilized Grimme's “D” term for evaluating dispersion forces that are weak [39]. Consequently, we performed the
The interaction of ethanol with pristine ZnO nanosheet
To inspect the adsorption of the ethanol, we selected a ZnO nanosheet model, which had 68 zinc and 68 oxygen atoms (Fig. 1). Formerly, the adsorption of N2, NO, CO, O2, N2O, CO2, and NH3 molecules have been considered computationally on a ZnO nanosheet model [41], [42], [43], [44]. The harmonic frequencies that we predicted ranged from 63.0 to 699.1 cm−1. The average Zn-O bond length is about 1.93 Å, being close to the value calculated by ref. [43], i.e., 1.92 Å. The molecular NBO analysis
Conclusions
Following an experimental work, we investigated the sensing performance of a ZnO nanosheet to ethanol using different density functionals. We showed that the pristine ZnO nanosheet cannot sense the ethanol gas, but the Ag atom insertion on the ZnO nanosheet surface significantly increases the sheet sensitivity in agreement with the experiment. The calculated Ag@ZnO nanosheet sensing response is 72 which is in good consistence with the experimental value of 50. This result demonstrated that
CRediT authorship contribution statement
Muhammad Harun Achmad: Data curation, Conceptualization. Ahmad Azhar Mansoor Al Sarraf: Methodology, Software. Dmitry O. Bokov: Writing – original draft. Indah Raya: Funding acquisition, Project administration. Maryam Derakhshandeh: Writing – review & editing, Supervision.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References (49)
- et al.
Chemical environment and magnetic moment effects on point defect formations in CoCrNi-based concentrated solid-solution alloys
Acta Mater.
(2020) - et al.
Effects of Al3+ on the microstructure and bioflocculation of anoxic sludge
J. Environ. Sci.
(2020) - et al.
Comparative study of thermally stratified tank using different heat transfer materials for concentrated solar power plant
Energy Rep.
(2021) - et al.
Hydrothermal preparation and gas sensing properties of Zn-doped SnO2 hierarchical architectures
Sens. Actuators B
(2014) - et al.
UV-enhanced room temperature NO2 sensor using ZnO nanorods modified with SnO2 nanoparticles
Sens. Actuators B
(2012) - et al.
High-performance and renewable supercapacitors based on TiO2 nanotube array electrodes treated by an electrochemical doping approach
Electrochim. Acta
(2014) - et al.
Review of ZnO-based nanomaterials in gas sensors
Solid State Ionics
(2021) - et al.
Atomic-level mediation in structural interparameter tradeoff of zinc oxide nanowires-based gas sensors: ZnO nanofilm/ZnO nanowire homojunction array
Applied Surface Science
(2021) - et al.
ZnO nanorod gas sensor for ethanol detection
Sensors and Actuators B: Chemical
(2012) - et al.
Flower-like hierarchical structures consisting of porous single-crystalline ZnO nanosheets and their gas sensing properties to volatile organic compounds (VOCs)
J. Alloys Compd.
(2015)