Doctor of Philosophy
Chemical and Biochemical Engineering
de Lasa, Hugo
The present PhD thesis reports the modification of titanium dioxide (TiO2) with palladium (Pd), to enhance hydrogen production via water splitting, using 2.0v/v% ethanol as a scavenger. Titanium dioxide was used as photocatalyst, given its ability to absorb photons, producing e-/h+ pairs. Mesoporous TiO2 was synthesized using a soft template, following the sol-gel method, to modify its morphological properties. Palladium was used as co-catalyst doping TiO2 agent, narrowing the band gaps down to 2.51 eV, and creating additional active metal sites.
Water splitting experiments under near-UV and visible light irradiation were carried out in the Photo-CREC Water-II Reactor (PCW-II) unit. It allows precise irradiation measurements, for macroscopic irradiation energy balances.
Redox reactions in the PCW-II led to hydrogen production and by-product compounds formation such as methane, ethane, ethylene, acetaldehyde, carbon monoxide, carbon dioxide and hydrogen peroxide. It was found that this redox reaction followed an “in series-parallel” network, involving the organic scavenger ethanol. Carbon balances, OH• and H• radical balances were obtained to validate the proposed reaction network. Furthermore, a kinetic model for photocatalytic water splitting for hydrogen production was developed, with the proposed kinetics and the associated kinetic parameters, being validated with experimental data, obtained in PCW-II unit.
Regarding energy efficiencies (QY%), it was observed that the prepared TiO2-Pd photocatalyst presented a promising QY% based on H· produced of up to 69.4% under near-UV irradiation, and of 17.6% under visible light for hydrogen production.
Summary for Lay Audience
The world community has been working towards the production of alternative energy sources to guarantee a sustainable life on Earth. Researchers have been exploring diverse alternatives in search of a clean and emission-free energy vector that can work as an alternative fuel. Hydrogen has attracted the attention of scientists and governments around the globe, given its great value as energy carrier with net-zero CO2 emissions when burned.
Photocatalysis is a promising environmentally friendly technology used to produce hydrogen via water splitting. It involves the use of sunlight, which is one of the most inexhaustible and renewable energy sources, to produce highly efficient and low-cost hydrogen. However, the photocatalytic water splitting reaction is not a spontaneous process in nature, it requires a semiconductor material capable of absorbing irradiation and a sacrificial agent such as ethanol, to allow the reaction to occur.
The present PhD thesis reports the modification of the titanium dioxide (TiO2) photocatalyst with palladium (Pd), in order to produce hydrogen via water splitting using 2.0v/v% ethanol as a scavenger. Water splitting experiments under near-UV and visible light irradiation were carried out in the Photo-CREC Water-II Reactor (PCW-II) unit leading to hydrogen production and by-products formation such as methane, ethane, ethylene, acetaldehyde, carbon monoxide, carbon dioxide and hydrogen peroxide.
It was observed that the prepared Pd-TiO2 photocatalyst presented promising quantum efficiencies under Near UV light of up to 69.4%, and under visible light irradiation of 17.6% towards hydrogen production via water splitting.
Rusinque, Bianca, "Hydrogen Production Via Photocatalytic Water Splitting Under Near-UV and Visible Light Using Doped Pd TiO2" (2021). Electronic Thesis and Dissertation Repository. 8053.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.