Molekul, Vol. 18. No. 1, March 2023: 140 – 146 140 MOLEKUL eISSN: 2503-0310 Articles https://doi.org/10.20884/1.jm.2023.18.1.7077 Does Divacancy Defect Combine with N,S-Codoping Enhance the Electronic Properties of Graphene to Its Interaction with K + Ion? Yuniawan Hidayat*, Fitria Rahmawati, Khoirina D Nugrahaningtyas, Abduro’uf Althof Abiyyi Chemistry Department, Sebelas Maret University, Jl. Ir Sutami 36A Surakarta, Indonesia *Corresponding author email: yuniawan.hidayat@staff.uns.ac.id Received November 03, 2022; Accepted February 15, 2023; Available online March 20, 2023 ABSTRACT. Defects in graphene alter its structure, electrical characteristics, and interaction with K + ions. The related characteristics of divacancy defect graphene and N, S codoped divacancy graphene were effectively explored using the DFTB technique. Divacancy is essential for the band gap opening. The dopants considerably enhance the density of state (DOS) intensity and alter the graphene-character bands. The depletion of density caused by the dopant is seen on the charge density isosurface. Because the charge of the K + ion is balanced by the dopant, the ion prefers to be adsorbed on divacancy graphene with dopants. Keywords: divacancy graphene, DFTB, fermi level, K + adsorption, N,S-codoping INTRODUCTION The electrical potential of the graphene anode in a potassium ion battery may be tuned to maximize the interaction with the K + ions (Hidayat et al., 2022). Nitrogen-doped graphene has unique properties compared to pristine graphene. The charge density of carbon’s surface is affected by the dopant and acts as an active site as a catalyst. Furthermore, the dopant responsible for the fermi level shifted above the Dirac point and pressed the DOS near Fermi to produce the gap between the conduction and valency bands (Joucken et al., 2015; Ketabi et al., 2016). The mechanical, thermal, and electrical conductivities properties of a crystal are all affected by defects in the crystal. A vacancy defect in graphene was caused by the loss of one or more carbon atoms, resulting in deformation in the bond length around the defect point (Olsson et al., 2019). On the surface of graphene, vacancy defects influence electron transfer, lowering graphene's conductivity but enhancing ion diffusivity and chemical reactivity (Pašti et al., 2018). Metal adsorption in the vacancy of graphene is energetically more favorable than on pristine graphene (Olsson et al., 2019). Dopants such as Nitrogen (N), Sulphur (S), Boron (B), and Phosphorus (P) can be advanced the electronic properties of graphene (Li et al., 2016). The simultaneous employment of two distinct dopants leads to a combination effect such as potential parameter, current density, and increased electron transport (Rivera et al., 2017; Su et al., 2013; Z. Yang et al., 2013; Zhu et al., 2013). The combination of vacancy defect and doped graphene advantage enhances the performance of carbon-based anode materials. DFTB (Density Functional Tight Binding) is a method based on a semiempirical approach that has roughly the same accuracy as the DFT method but the calculation time is shorter. The benefit of the DFTB technique is that it makes it feasible to compute the electronic structural characteristics of large molecule systems, which cannot be taken advantage of by the conventional ab initio method (Spiegelman et al., 2020). The DFTB approach has been effectively applied to examine redox reaction systems and anticipates features of molecular electronics related to the chemical activity of solids, supramolecules, and carbon (Poh et al., 2016; Selli et al., 2017; Sengupta et al., 2021; Zhang et al., 2020). This work presents the DFTB approach for investigating the relationship of vacancy defect graphene with the presence of co-dopant N and S to its electronic behavior in terms of fermi level shifts, DOS changes, and energy band structures. Their impact on interactions with the K + ion was also studied. To clarify, four graphene structural models were used: divacancy graphene (V2G), N, S codoped divacancy graphene (NSV2G), K + ion on divacancy graphene (K-V2G), and K + ion on the N and S doped divacancy graphene (K-NSV2G). EXPERIMENTAL SECTION Pristine graphene based on the crystal characteristics of Kristin Person, 2014 (Persson, 2014) was modified to divacancy graphene (V2G)