Background

Perovskite oxides are highly versatile materials with an ABO₃ crystal structure. Substitution of metals at the A- and B-sites can be used to tailor their structural, chemical and catalytic properties. Under reducing conditions, selected B-site metals can migrate from the perovskite lattice and form nanoparticles on the material surface through a process known as exsolution. These nanoparticles are typically well dispersed and partially embedded within the oxide support, providing improved stability under harsh reaction conditions.

Most exsolved nanoparticles reported in the literature are spherical, and the factors controlling the formation of alternative shapes remain poorly understood. Preliminary work in our group has shown that A-site modification can promote the formation of pyramidal Ni nanoparticles alongside conventional spherical particles. These different particle morphologies exhibit substantially different catalytic selectivity during CO₂ hydrogenation. This project will investigate how morphology can be further controlled to modulate the morphology of the exsolved Ni nanoparticles to further optimise catalyst performance.

Project Objectives

• Synthesise substituted perovskite catalysts containing an exsolvable metal.
• Select and investigate one catalyst design variable following a literature review.
• Determine how the selected variable influences phase formation and exsolved nanoparticle morphology.
• Relate nanoparticle size, shape and population density to catalytic performance.
• Evaluate selected catalysts for thermal and/or photo-promoted CO₂ hydrogenation.

Project Tasks

• Review the literature on perovskite oxides, nanoparticle exsolution and morphology control.
• Select one design variable, such as composition, A-site deficiency, reduction temperature, reduction duration, reduction atmosphere or synthesis conditions.
• Prepare a series of perovskite catalyst materials.
• Conduct controlled reduction treatments to induce metal exsolution.
• Assist in analysing catalyst characterisation data, including XRD and electron microscopy images.
• Assess catalyst performance for CO₂ hydrogenation performance using a lab-scale reactor.

Expected Learning Outcomes

• Perovskite and heterogeneous catalyst synthesis
• Catalyst characterisation 
• Gas-phase catalytic reaction testing
• Experimental planning and laboratory safety
• Scientific data analysis and interpretation
• Technical report and thesis writing

Research Environment and Supervision

This project will be conducted in the Particles and Catalysis Research Group at the UNSW School of Chemical Engineering. The group conducts research in heterogeneous catalysis, carbon dioxide utilisation, hydrogen technologies, photothermal catalysis and advanced materials characterisation.

The student will work closely with Partcat members and receive training in catalyst synthesis, sample preparation, experimental planning and data analysis. Advanced characterisation, particularly electron microscopy, will be undertaken with assistance from experienced researchers, while the student will focus primarily on catalyst preparation, controlled exsolution experiments, performance testing and interpretation of the resulting data.

Supervisors: A/Prof Jason Scott and/or A/Prof Emma Lovell

References

https://doi.org/10.1016/j.cej.2020.127557

https://doi.org/10.1039/d4cc01983k

https://doi.org/10.1016/j.cej.2022.136025