研究目的
To investigate the modulated electronic and optical properties of TiO2 with Pt/Ag substitutional dopants using first-principles density functional theory to tailor it as an efficient photocatalyst in the visible region.
研究成果
Pt and Ag doping significantly reduce the band gap of TiO2 and shift absorption to the visible region, with Pt-doped structures showing direct band gaps and Ag-doped structures showing indirect or half-metallic behavior. The enhanced optical properties, including higher absorption, reflectivity, and refractive index in the visible spectrum, suggest that Pt/Ag-doped TiO2 can be tailored as an efficient photocatalyst for visible light applications.
研究不足
The study is computational and based on DFT calculations, which may underestimate band gaps (e.g., pristine TiO2 band gap calculated as 1.5 eV vs. experimental 3.23 eV). Optical properties are only calculated for 8.33% impurity due to computational expense. Experimental validation is not included, and the focus is on anatase phase only.
1：Experimental Design and Method Selection:
The study uses first-principles density functional theory (DFT) within the Vienna Ab-initio Simulation Program (VASP) package with the Perdew-Burke-Ernzhof (PAW-PBE) exchange functional of the Generalized Gradient Approximation (GGA) for ground state structural optimization and electronic properties calculation. Optical properties are evaluated using the dielectric tensor calculated via the Kubo-Greenwood formula, neglecting local field effects.
2：Sample Selection and Data Sources:
A 2x1x1 supercell of TiO2 with 8 titanium and 16 oxygen atoms is used. Substitutional doping concentrations of Pt and Ag are varied at
3：17%, 33%, and 5%. List of Experimental Equipment and Materials:
Computational software VASP is used; no physical equipment is mentioned as it is a theoretical study. Materials include TiO2 supercells doped with Pt and Ag.
4：Experimental Procedures and Operational Workflow:
Structures are fully relaxed including lattice parameters and ionic positions until energies and forces reach values of 10?5 eV and
5：001 eV/? respectively. Formation energies are calculated, and electronic and optical properties are analyzed using density of states, charge density plots, and optical parameters derived from the dielectric function. Data Analysis Methods:
Data analysis involves spin-polarized density of states, Bader charge analysis for charge transfer, and calculation of optical properties such as reflectivity, absorption coefficient, refractive index, energy loss spectrum, and extinction coefficient using DFT level random phase approximation.
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