Comparative investigation of the bulk and electronic properties of dimethyl disulphide adsorbed indium doped zigzag graphene nanoribbon: A DFT Study

For the purpose of understanding the adsorption process using the density functional theory method, the bulk and electronic properties of the complex consisting of dimethyl disulphide (C2H6S2) and indium doped zigzag graphene nanoribbon are investigated. Also, a comparison with the electronic and bulk characteristics of indium-doped zigzag graphene nanoribbon is made with molecule adsorbed zigzag graphene nanoribbon. Following complete geometric optimization, the electronic and bulk characteristics are calculated. The stated complex’s structural changes exhibit observable differences, prompting further research based on its electronic properties. Calculating the complex’s various electronic properties reveals that it possesses semi metallic behavior.


Introduction
A typical volatile organic molecule called dimethyl disulphide (DMDS) is utilised to determine the amount of sulphur nutrients in the rhizosphere.This nutrient can be found in current agricultural practises using volatile organic compound profiling, which enables the shortage to be filled externally.Recent advancements in the field of two-dimensional nanomaterials aided gas sensing have received wide recognition because of the different special features of graphene nanoribbon.By including imperfections, dopants, and other additives to this nanoribbon, it is possible to manipulate its bandgap and consequently its properties.
The discovery of graphene, the first nanomaterial in two dimensions, opened the door for the discovery of many other two-dimensional nanomaterials [5].Numerous methods can be employed to engineer graphene's special qualities [6].Cutting graphene into single layers with a limited length yields graphene nanoribbons (GNR) [7].Among its many special characteristics are high carrier mobility, flexible bandgap, semiconducting behaviour, and mechanical durability [8][9][10].
Due to these characteristics, GNRs are a desirable choice for sensing applications; articles in the literature have looked at the detection of several gases using GNRs [11][12][13].To be more precise, the creation of ultra-sensitive detectors that have substantial packing density, higher selectivity, greater sensitiveness, rapid recoverability, and less electrical consumption is greatly aided by the use of nanoribbons made of graphene for sensing applications [14].
In this work, dimethyl disulphide nanomaterials are detected utilizing Indium, as the doped zigzag nanoribbons made of graphene (I-ZGNR) and the density functional theory approach.Calculating the complex's bulk and electrical properties following complete geometric optimization is the investigation's task.By encouraging plant development and defense systems, this discovery can be utilized to improve farming practices and is essential to smart agriculture [21].The document's remaining sections are organized as follows: The results and an explanation of the nanosensing application are presented in Section 3, which is followed by the final paragraph.In Section 2, the bulk and electrical properties of the DMDS-Indium modified ZGNR compound are computationally investigated.

Computational Method
With the aid from the Virtual Nano-Lab Atomistix Toolkit, indium doped ZGNR is being studied for the sensing of DMDS that promotes plant development [15].To establish the application of the mentioned nanoribbon in the detecting of DMDS, extensive calculations are carried out on the overall structure and electrical characteristics of the complicated substance under discussion in this inquiry [22].Using density functional theory, the bulk and electronics computations are carried out from first principles (DFT).The Perdew-Burke-Ernzerhof generalized gradient approach [16] utilizing a doublezeta polarized basis set served as the foundation for the exchange-correlation the basis set [17].One indium atom is used for ZGNR doping [18].

Bulk analysis
Six atoms make up per ZGNR dimension (w = 6).Surfaces are passivated by hydrogen atoms because they are fewer reactive than edges.Certain literary works claim that the sensing properties of graphene can be altered by carefully placing imperfections or dopants [14].Doping is present in GNR to improve its characteristics [18], [20].The following formula is used to calculate the adsorption energy: Where The considerable adsorption energy of -24.03756eVafter relaxing between the molecule and the Indium doped ZGNR complex points to the potential for dimethyl disulphide has shown adsorption properties in indium doped ZGNR.Dimethyl disulphide with Indium doped ZGNR also has an energy gap of -0.017eV, showing semimetal characteristics.The acquired calculation findings allow for future investigation of this complex's electrical characteristics in order to determine its suitability for dimethyl disulphide sensing, a type of plant VOC detection.

Band structure analysis
To investigate the variations between the electronic properties with Indium doped ZGNR prior to and following di-methyl di-sulphide adsorption, the band gap is estimated.The electrical energy of the potential electronic states is represented by an array of lines in a mutually exclusive space called the band structure.The energy levels of the complex are represented by band gaps, also known as prohibited gaps, on the band diagram.A tiny bandgap overlap is revealed by the bandstructure analysis, as seen in Fig. 2. Semimetal characteristics can be seen in the bandstructure of indiumdoped ZGNR adsorbed with molecule.Z and Γ are the wave vectors that are used to compute the bandstructure.

Analysis of density of states
The average density of states (DOS) for this substance is investigated in order to track the chemical relationship of di-methyl di-sulphide using Indium doped ZGNR.The DOS plot displays the potential energetically advantageous states that can be occupied.It shows the number of allowed electron (or hole) states in a volume at a given energy.As such, they provide information on energy distributions and carrier concentrations.The DOS charts for indium-doped ZGNR with and without di-methyl disulphide adsorption are shown in Figures 3(a

Analysis of transmission spectrum
All of the modes that are reachable at every energy level in the band structure add up to the transmission spectrum.The transmission spectrum study for indium-doped ZGNR utilizing di-methyl di-sulphide is shown in Figure 4. Analysis reveals that the transmission spectra plot agrees with the complex's behaviour in the density of states, consequent, and structural analyses of Figures 2 and 3.
This study confirms previous findings by demonstrating that Indium doped ZGNR with di-methyl disulphide exhibits semi-metallic behaviour.As shown in Fig. 4 for the Indium doped ZGNR with dimethyl disulphide, the transmission has a high value near the Fermi level.The transmission function peak has the highest value near the Fermi level as is seen in Figure 4 (b), indicating that transmission channels near the Fermi level dominate electron transport.As from the Energy Gap Eg, Density of states (DOS) and transmission spectrum there is a charge variation along fermi level, which can be seen through band gap, density of charge carriers and peaks of the transmission spectrum shows semi metallic properties.Hence after investigation of bulk properties and comparing the results of indium doped nanoribbon DMDS with pure ZGNR band gap reduces.

Conclusion
Dimethyl disulphide's existence is critical in meeting the nutritional needs of the plant.However, low or absent levels of this essential sulphur-rich VOC can inhibit plant growth.Thus, the sensing of dimethyl di-sulphide (C2H6S2) with Indium doped Z-GNR is investigated by calculating the complex's bulk and electrical properties following relaxation.The bulk property studies involve the computation of energy bandgap, adsorption energy, and distance after relaxation.The data that were obtained show how the adsorption process occurred.Through the use of transmission spectrum analysis, density of states analysis, and bandstructure analysis, the electrical characteristics of Indium doped ZGNR with di-methyl di-sulphide were examined.. Since bandstructure is synchronized with State density and transmission spectrum density which reveals and verifies that electrical properties of Indium doped ZGNR with di-methyl shows semi-metallic behaviour after investigation.

Figure 1 .
Figure 1.Optimized Indium doped ZGNR (a) without DMDS (b) with DMDS (C, H, S and In atoms presented as green, pink, blue and brown coloured atoms)

Figure 3 .
Figure 3. DOS of (a) purest form of Z-GNR (b) Indium doped with di-methyl di-sulphide

Table 1 .
EIn-ZGNR+DMDS, EIn-ZGNR and EDMDS denote the total strengths for the Indium doped ZGNR molecule convoluted, doped Indium ZGNR, or the standalone DMDS molecule are indicated by the symbols.1327(2024)012025Bondlengths of optimized complex and adsorption distance calculations thorough examination of the adsorption behavior amongst DMDS molecules or Indium doped ZGNR (Ead) necessitates calculating the parameters of the relaxing structure acquired after optimization, which is energy gap (Eg) and adsorption energy, which are shown in Table2.In addition, Table2displays the values of the energy gap Eg, lowest vacant molecular orbital (LUMO), and maximum populated molecular orbital (HOMO) for Indium doped ZGNR with dimethyl sulfide. A