(569en) Investigating Ceria-Doped Titania Nanostructures for Photocatalytic NOx Degradation

Titania has been considered the gold standard for photocatalytic NOx degradation; however, it has several limitations, including fast charge recombination and poor visible light sensitivity that make it unsuitable for widespread outdoor applications. Doping has shown promise in inducing visible light sensitivity with titania. Ceria is a rare earth metal oxide that has been used as a catalyst or support in reactions such as water-gas shift, photoelectrochemical water splitting, and three-way catalytic removal of CO, NO, and hydrocarbons. Its most notable properties are its small band gap, high basicity, and interconvertibility between Ce³⁺ and Ce⁴⁺ oxidation states. Ceria has been used as a dopant for titania nanoparticles in selective catalytic reduction (SCR) of NO_x, liquid-phase photocatalytic degradation, and photoelectrochemical water splitting. Ceria is known to form a Z-scheme heterojunction with TiO₂ that is visible light active, with the CeO₂ forming superoxide radicals and the TiO₂ forming hydroxyl radicals. While CeO₂/TiO₂ photocatalysts have been used extensively in other reactions, little is known about their effectiveness in NO_x degradation. This study investigates the use of CeO₂-doped TiO₂ nanostructures in NO_x degradation, as well as investigations into different TiO₂ nanostructures, optimal dopant concentration, and doping methods and how these factors impact the band gap. It is expected that band-gap tunable nanomaterials will be possible from these investigations.