Light-induced Energy Production Using Plasmonic Photocatalysis

• Author / Creator

  Vahidzadeh, Ehsan

• Diversifying the energy sources and finding an alternative for fossil fuels is the new global challenge. To this end, utilizing solar light to produce energy carriers such as hydrogen and hydrocarbons attracted tremendous attention. Hydrogen and methane can be produced through photo-induced processes named water-splitting and CO2 photoreduction, respectively. Water-splitting is the process where water molecules are broken into hydrogen and oxygen. The hydrogen produced in this process can be utilized for applications such as fuel cells or hydrogen-powered vehicles. The CO2 photoreduction process converts CO2 (which is considered waste and the major contributor to global warming) into valuable products. As a result, this process is regarded as the missing puzzle piece to address the global warming issue. The practical application of these two processes is contingent upon the fabrication of highly efficient photocatalysts. Photocatalysts are a family of heterogeneous catalysts that can increase the rate of chemical reactions by producing photogenerated electron-hole pairs. Since the interaction with light is a primary step in a photocatalytic reaction, engineering the light absorption properties, increasing the electron-hole pair generation, and suppressing their recombination is key to improving their efficiency. The most novel direction in photocatalysis research is plasmonic photocatalysis. Plasmonic materials are usually metal nanoparticles such as Au and Ag. Plasmonic metal nanoparticles can interact extensively with incident light, making them an interesting nominee for photocatalytic applications. The advantages of using plasmonic materials for applications such as CO2 photoreduction and water-splitting motivated me to investigate their ability to drive these chemical reactions.
  In the first step of my Ph.D. studies, a heterojunction between bimetallic plasmonic (AgCu) nanoparticles with semiconductor (TiO2 nanotube arrays) was fabricated through a facile photo deposition technique. These samples were characterized with state-of-the-art characterization techniques and utilized for CO2 photoreduction reaction.
  In the second step, core-shell Au@a-TiO2 photoelectrodes were fabricated and utilized for photoelectrochemical water-splitting reaction. The mechanism of the charge transfer between the Au and a-TiO2 was investigated using several experiments such as surface potential measurement using Kelvin probe force microscopy and conducting the water-splitting reaction in the presence of a hole scavenger. The Au@a-TiO2 photoelectrode fabricated in this step exhibited remarkable photocurrent responses with high faradaic efficiency.
  In the third step, sponge-shaped Au nanoparticles (Au-Sponge) were fabricated using a creative dewetting followed by dealloying technique. Au-Sponge samples were utilized for CO2 photoreduction reaction. In comparison with regular spherical-shaped Au nanoparticles (Au-Island) the Au-Sponge sample exhibited outstanding photocatalytic performance.

• Subjects / Keywords

  • Plasmon
  • Photocatalysis
  • Solar Energy

• Graduation date

  Fall 2021

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-zvfb-tf68

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.