High-Performance Low-Cost Catalysts for Water Electrolysis: A Computational and Experimental Study

Hydrogen (H2) is a high-density energy carrier expected to play a key role in achieving global net-zero emissions. Research and development of low-cost, highly active and durable transition metal oxide (TMO) catalysts for water electrolysis is a requirement to enable H2 production on a large scale. However, the water electrolysis process is hindered by the oxygen evolution reaction (OER), which has slow kinetics and a high overpotential, and this issue remains unresolved. This thesis employs density functional theory (DFT) to rationally design and develop low-cost, highly active, and durable TMO catalysts prepared by plasma-enhanced atomic layer deposition (PE-ALD) for the alkaline OER. A benchmark of different exchange-correlation (XC) functionals addresses the issue of the DFT level of theory for modelling the electronic structure of strongly correlated 3d metal oxides. The assessment of the XC reveals that PBE0 functional is the best for modelling 3d metal oxides. The results highlight the importance of using advanced XC functionals that can accurately capture the complex electronic interactions in 3d TMO with a reasonable computational cost and contribute to developing XC functionals for materials science modelling studies. The role of Zn2+, Al3+, and Sn4+ dopants in promoting the OER activity of NiOx catalysts is assessed. The catalysts are synthesised by PE-ALD, and the electronic structure is modelled by a high-level DFT. The best OER performance is obtained in SnNiOx, with 268 mV overpotential at 10 mA/cm2 and exceptional durability. The study reveals that a higher oxidation state and larger orbital overlap in the M–O bonding promotes charge accumulation and delocalisation, which enhances OER activity. The findings demonstrate the potential of PE-ALD and DFT to prepare and tune highly-active doped NiOx nanofilms for sustainable energy applications. Last, the OER activity is enhanced by atomically dispersed catalysts (ADCs) of Fe1 and Co1 supported on SnNiOx. Electrochemical measurements demonstrated that Fe1 and Co1 ADCs prepared with H2 plasma significantly enhanced OER activity by reducing charge-transfer resistance. The best catalyst, Fe1Co1/SnNiOx prepared with H2 plasma, sets a new record of 253 mV overpotential at mA/cm2 measured in fluorine tin oxide (FTO). This study highlights the potential of PE-ALD to synthesise ADCs as promising candidates for OER catalysis. This thesis contributes to a deeper understanding of the electronic factors in TMOs influencing OER activity and provides insight into new technologies for designing and fabricating low-cost, active, and durable catalysts for alkaline electrolysers. The findings will accelerate the development of clean and sustainable energy technologies.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2025

Author dc:creator

• Oestroem, Ina

• Water electrolysis
• Oxygen Evolution Reaction
• Electrocatalysts
• Hydrogen
• Heterogenos Catalysis
• Atomic Layer Depostion
• Density Functional Theory
• anzsrc-for: 340604 Electrochemistry
• anzsrc-for: 340704 Theoretical quantum chemistry
• anzsrc-for: 400803 Electrical energy generation (incl. renewables, excl. photovoltaics)
• anzsrc-for: 340601 Catalysis and mechanisms of reactions
• anzsrc-for: 340602 Chemical thermodynamics and energetics
• anzsrc-for: 340607 Reaction kinetics and dynamics
• anzsrc-for: 340701 Computational chemistry
• anzsrc-for: 340210 Solid state chemistry
• anzsrc-for: 340211 Transition metal chemistry
• anzsrc-for: 401807 Nanomaterials

Statement dc:rights

• embargoed access
• CC BY 4.0

Licence

• http://purl.org/coar/access_right/c_f1cf
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/31039

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/104673