Lanthanum nickel oxide based double perovskites and their exsolution phenomena
File(s)
Author(s)
Guo, Jia
Type
Thesis
Abstract
The increasing energy demand and the need to reduce greenhouse gas emissions are driving a transition to renewable energy sources. Solid-oxide cells (SOCs) offer promise for integrating intermittent renewables into the grid, yet current fuel electrode materials, exemplified by Ni cermet, face limitations including degradation and poisoning. A novel approach called 'exsolution,' involving the creation of metal nanoparticle-decorated oxides, is gaining traction for its potential to improve SOCs by producing stable and efficient electrode materials.
This thesis investigates double perovskite materials as potential fuel electrodes due to their favourable electrochemical properties and unique exsolution behaviour. Specifically, lanthanum nickel ruthenates (LaxNiRuO6-y, x = 2, 1.9,1.85) and ruthenium-doped lanthanum nickel titanates (LaxNiTi0.9Ru0.1O6-δ, x = 2, 1.85) were studied. A-site deficiency was found to facilitate exsolution. Notably, A-site deficient lanthanum nickel ruthenate (La1.85NiRuO6-y) exhibited exsolution of Ni and Ru cations at relatively low temperatures, with particle size increasing at higher temperatures. In this study, La1.85NiRuO6-y underwent exsolution of Ni and Ru cations at 450°C, with separate B-site cation exsolution initiating at lower temperatures (300~360°C). In-situ microscopy and electrochemical analysis confirmed rapid exsolution at 450°C, resulting in enhanced electrochemical performance in single cells test due to the exsolution of Ni-Ru bimetallic nanoparticles.
A-site deficient ruthenium-doped lanthanum nickel titanates (La1.85NiTi0.9Ru0.1O6-δ) displayed exsolution of Ni nanoparticles over a wide temperature range, contrasting with Ru cations, which required extremely high temperatures for exsolution. The thesis proposes a critical temperature range (400-450°C) influencing exsolution behaviour. Additionally, attempts to replace exsolved cations with infiltrated iron cations showed enhanced exsolution of Ni-Ru alloy nanoparticles.
In summary, this thesis extensively examines double perovskite materials as fuel electrodes for SOCs, emphasizing their exsolution behaviours. It illuminates exsolution in B-site ordered double perovskites with varied cation properties and proposes metal nanoparticle-decorated lanthanum nickel ruthenates and titanates as promising SOC fuel electrode candidates.
This thesis investigates double perovskite materials as potential fuel electrodes due to their favourable electrochemical properties and unique exsolution behaviour. Specifically, lanthanum nickel ruthenates (LaxNiRuO6-y, x = 2, 1.9,1.85) and ruthenium-doped lanthanum nickel titanates (LaxNiTi0.9Ru0.1O6-δ, x = 2, 1.85) were studied. A-site deficiency was found to facilitate exsolution. Notably, A-site deficient lanthanum nickel ruthenate (La1.85NiRuO6-y) exhibited exsolution of Ni and Ru cations at relatively low temperatures, with particle size increasing at higher temperatures. In this study, La1.85NiRuO6-y underwent exsolution of Ni and Ru cations at 450°C, with separate B-site cation exsolution initiating at lower temperatures (300~360°C). In-situ microscopy and electrochemical analysis confirmed rapid exsolution at 450°C, resulting in enhanced electrochemical performance in single cells test due to the exsolution of Ni-Ru bimetallic nanoparticles.
A-site deficient ruthenium-doped lanthanum nickel titanates (La1.85NiTi0.9Ru0.1O6-δ) displayed exsolution of Ni nanoparticles over a wide temperature range, contrasting with Ru cations, which required extremely high temperatures for exsolution. The thesis proposes a critical temperature range (400-450°C) influencing exsolution behaviour. Additionally, attempts to replace exsolved cations with infiltrated iron cations showed enhanced exsolution of Ni-Ru alloy nanoparticles.
In summary, this thesis extensively examines double perovskite materials as fuel electrodes for SOCs, emphasizing their exsolution behaviours. It illuminates exsolution in B-site ordered double perovskites with varied cation properties and proposes metal nanoparticle-decorated lanthanum nickel ruthenates and titanates as promising SOC fuel electrode candidates.
Version
Open Access
Date Issued
2023-10-24
Date Awarded
2024-03-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Skinner, Stephen
Stephens, Ifan
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)
Rights Embargo Date
2026-02-28