| Author: | Lu, Qiuyang |
| Title: | Energy conversion modeling in applications of electron dynamics, catalysis, and biological tools |
| Advisors: | Huang, Bolong (ABCT) Shi, Sanqiang (ME) |
| Degree: | Ph.D. |
| Year: | 2023 |
| Subject: | Energy conversion Nanostructured materials Hong Kong Polytechnic University -- Dissertations |
| Department: | Department of Applied Biology and Chemical Technology |
| Pages: | 157 pages : color illustrations |
| Language: | English |
| Abstract: | It has been well accepted that atomic-level analysis based on electronic configurations and kinetics may have the potential to assist and deepen the studies surrounding nanomaterials, including nanophosphors, nanogenerators, and bio-metal interactions. Nowadays, researchers combine both experimental and theoretical results for developing computational methods to deepen the investigations. An energy conversion model based on electron kinetics is introduced for presenting and interpreting the energy conversion diversity and the electron transmission processes inside nanomaterials. Here, the model is mainly focused on the electron transition mechanism as well as the dependence on the pump power and the condition of intermediate states. Among them, photon upconversion (UC) involving multiple electron transition processes has been widely studied due to its complicity and significance in laser materials. UC is generally referred to a process in which the sequential absorption of two or more photons can induce luminescence at a shorter wavelength. The basic characteristics and mechanisms of UC have been fundamentally established in the past and further validated with the availability of lasers. From the mid-1960s, the observation of multiphoton upconversion of rare earth ions in inorganic solids started, and complicated electronic transitions are also revealed and elaborated, such as light-matter interactions, ion-lattice interactions, multi-ion collective actions, and phonon-assisted energy transfer. Such electronic transition processes can randomly occur in a particular UC phenomenon, and the intertwined transition mechanism may make it more difficult to accomplish a comprehensive and coherent understanding of the complex upconversion systems. At the same time, the quest for establishing sufficient theoretical methods has also been exploited. The free-ion energy levels and crystal-field splitting of 4fN as well as excited configurations can be unified via the standard framework.1 After demonstrating the primary understanding of the kinetic characteristics of UC systems, further altering the transition rate coefficients can derive more complicated situations about the cross-relaxation, upconversion, downconversion, and depletion process among the five-level model. Based on the understanding towards the electron kinetic model, the description of a basic NaYF4 system is applied to verify the reliability and feasibility of the model. The simulation results reveal a good match with the transition mechanisms of NaYF4. A kinetic model describing the Pd-based nanocrystal catalyst for electrosynthesis of H2O2 is defined by the refined equations. We also employed analysis about the parameters governing upconversion efficiency. Besides, the bio-metal interactions between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike protein and noble metal surfaces are also studied by an energy affinity model constructed based on density functional theory (DFT). Au, Pt, Cu, and Pd nanoparticles, protein segments on Spike protein are chosen and constituted as well as metal surfaces with Material Studio Software. After real-time monitoring, the probability and affinity of protein-metal binding are indicated by absorption energy, orbital interactions, and electronic structures when the contact occurs. |
| Rights: | All rights reserved |
| Access: | open access |
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