Plasmonic Titania Based Heterojunction Photocatalyst for Clean Energy Production and Environmental Remediation

Abstract

Solar photocatalysis using advanced metal oxide semiconductors offers a sustainable and promising pathway for clean energy production and environmental remediation. After the discovery of water splitting using titania in 1972 by Fujishima and Honda, titania has been extensively studied for various photocatalytic applications due to its high stability, nontoxicity, and strong oxidative capabilities. However, wide band gap (3.0-3.4 eV) of titania limits its photon absorption to UV region of the total solar spectrum. In the modern material engineering, sensitizing titania with plasmonic noble metal nanoparticles (specially silver (Ag) and gold (Au)) grabs great attention due to their ability to elevate the photon absorption towards visible region by surface plasmon resonance effect and its effective charge carrier separation at the interface due to the Schottky junction. Additionally, polymorphic titania heterojunction, containing anatase and rutile phase, offers better charge carrier separation compared to its pristine counterparts. Combining these two approaches and optimizing the morphology of the catalyst may further enhance the solar photocatalytic performance of titania. However, considering the cost difference between Ag and Au, sensitizing titania with Ag is found to be a more viable and cost effective choice. Keeping this in mind, this thesis aims to design Ag sensitized plasmonic enabled pristine and heterojunction titania based photocatalyst to enhance the charge carrier dynamics and photocatalytic performance. This thesis explores the optimization of the plasmonic effect of Ag on titania based photocatalysts by systematically investigating the key parameters, such as Ag concentration, nanoparticle size, morphology, and distribution, to enhance its photocatalytic performance for both hydrogen evolution and dye degradation.