Study and design of (110) layered perovskites for photocatalytic applications

Abstract

Photocatalysis is a promising technique for addressing energy scarcity and environmental pollution. Layered perovskites with the formula of AₙBₙO₃ₙ+2 are promising materials for photocatalytic application due to their unique layered structure and electronic properties. However, their practical applications are hindered by the wide bandgaps, poor light utilization ability, and rapid recombination of photogenerated charges. In this project, we focused on modifying materials from the layered perovskite family, such as La₂Ti₂O₇ and Pr₂Ti₂O₇, through doping and heterojunction techniques to optimize their photocatalytic performance.

We specifically investigated the effects of foreign atoms, namely Ag, and Al/Nb, on the crystal and electronic structure, morphology, band energy, and photocatalytic properties of La₂Ti₂O₇. Our results indicated that Ag modified La₂Ti₂O₇ demonstrated superior performance in methyl orange and rhodamine B photodegradation compared to pristine La₂Ti₂O₇. Several key findings contributed to this enhancement, such as increased specific surface areas, enhanced light absorption due to surface plasma effect, and improved charge separation, etc. On the other hand, we found that Al/Nb co-doped La₂Ti₂O₇ displayed enhanced H₂ evolution activities compared to pristine La₂Ti₂O₇. This enhancement can be attributed to various advantages introduced by the
incorporation of Al/Nb, such as increased BET area, better charge transfer capacity, etc. Importantly, the simultaneous incorporation of acceptors and donors played a crucial role in adjusting charge distribution and promoting their efficient separation.

Moreover, we constructed heterojunction materials based on Pr₂Ti₂O₇ and Ag₃PO₄. Our results indicate that the hybrid photocatalysts exhibited remarkable photocatalytic performance in degrading various organic dyes (methyl orange, methylene blue, and rhodamine B) under both visible and UV-vis light sources. The optimal composite was observed in the sample of Pr₂Ti₂O₇:Ag₃PO₄ (1:3), which displayed significant enhancement in dye photodegradation compared to bare Pr₂Ti₂O₇ and Ag₃PO₄, even surpassing commercial P25 in terms of methylene blue and rhodamine B degradation. The reaction mechanism was also probed by the radical capture experiments

Date of Award	13 Jun 2024
Original language	English
Awarding Institution	University of St Andrews
Supervisor	John Thomas Sirr Irvine (Supervisor)