Characterization of Biogenic VO2 and Pt-doped VO2 Nanoparticle Synthesized by Shewanella sp. HN-41

Abstract

Vanadium dioxide (VO2) has been attracted in a few decades due to its unique characteristics caused by reversible phase transition such as metal-insulator transition and change in the transmittance of infrared ray. Therefore, various synthetic methods were reported for synthesizing VO2. For examples, hydrothermal methods, vapor transport methods, and sol-gel methods. However, the methods require reducing agents and energy consuming reaction for high temperature and pressure. In our study, we first reported the biological synthetic method of VO2 nanoparticles using Shewanella sp. HN-41 by reducing V2O5 as an electron acceptor at room temperature under anaerobic condition. Our method is eco-friendly synthetic method in the aspect of low energy consuming and absence of reducing agents in the reaction. In chapter 1, we characterized biogenic VO2 nanoparticles and its secretion mechanism from bacterial cell. Biogenic VO2 nanoparticles were crystalline and circular shape. Average size of the particles was 4.3 nm. VO2 nanoparticles were characterized to M2 phase VO2 by XRD analysis. Shewanella sp. HN-41 secreted VO2 nanoparticles as membrane vehicle. Shewanella sp. HN-41 transported VO2 nanoparticles from cytoplasm to periplasm. Consequently, Bacterial cell swelled outer membrane for secreting VO2 nanoparticles as membrane vehicle. In chapter 2, we doped platinum (Pt) into VO2 nanoparticles for application as hydrogen storage material by reducing dissociation energy of