First-principles investigation of doping via single atom vacancy or substitution of Pd or Se with Fe, Co, Cu, or Zn in monolayer palladium diselenide and its effects on quantum capacitance

• Main Author: Paz, Kyle Alfred C.
• Format: text
• Language: English
• Published: Animo Repository 2024
• Subjects: Semiconductor doping; Monomolecular films; Palladium compounds; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etdm_physics/19
• Institution: De La Salle University

The shift to renewable energy is one of the most important goals for human life sustainability. Researchers have taken the initiative to investigate the viability of 2D materials as supercapacitor electrodes for renewable energy applications. The monolayer palladium diselenide (PdSe2) is a 2D semiconductor similar to graphene, and shares its novel properties such as high electron mobility, high conductivity, and high surface area per unit mass. These properties are ideal for supercapacitor electrodes. In this study, the monolayer palladium diselenide was introduced with point defects via vacancy or Pd or Se substitution with Fe, Co, Cu, or Zn, and observed if the process of doping will increase its viability as a supercapacitor electrode. A total of 13 systems were modeled in this study, their stabilities were gauged through formation energy. The formation energies of all vacated systems are negative, indicating a spontaneous formation, and relatively low formation energies were observed in the substituted system which could mean that the systems could be energetically efficient to form, the most stable of which are selected for further calculations. Bader charges and density of states were calculated for the electronic structure of the material, and a correlation between the presence of charge accumulation points and the semiconducting nature of the material was found to persist for the doped systems. Quantum capacitance is the principal property to gauge the capacitance of a 2D semiconductor because quantum effects are apparent for materials that have a lower number of states available near the fermi level. The quantum capacitance of all doped systems increased in the negative voltage. Having a peak quantum capacitance of 750 μF/cm2, 1x1 Se vacated system is the most notable increase in quantum capacitance. It surpassed the values of other graphene based electrodes. The results shown were promising, but still needs to be supplemented with experimental data in the future to solidify any claims.