Probing the Chemistry of Fuel Cells with 71 Ga NMR Spectroscopy

Published August 14, 2024

Left: The electrolyte material incorporated in a solid oxide fuel cell. Right: 71Ga solid-state NMR spectra and computational models showing gallium with different numbers (4, 5, and 6) of proximate oxygen ions. Asterisks (*) indicate artefacts.

Lucia Corti, University of Liverpool

Solid oxide fuel cells generate clean energy by oxidizing green fuels like hydrogen and reducing atmospheric oxygen, without recharging or emissions that contribute to climate change. They use a fast ion conductor electrolyte to move oxygen ions between electrodes, converting chemical energy to power. Our research uses ⁷¹Ga solid-state NMR spectroscopy on the highest-field magnet in the world to study the numbers of oxygen ions near gallium atoms – this will inform the design of better electrolyte materials for fuel cells.

Solid oxide fuel cells are advanced devices that generate clean energy by using hydrogen as fuel and oxygen from the air. They produce electricity without harmful emissions, addressing environmental concerns. These fuel cells don't need recharging and can continuously power things like vehicles and buildings.

All fuel cells work in a similar way: they have a negative electrode (anode) and a positive electrode (cathode) with an electrolyte in between. In solid oxide fuel cells, the electrolyte moves oxygen ions between the electrodes to convert chemical energy into electricity. This process needs special materials with defects in their atomic structures that can hold different numbers of oxygen ions. Gallium (Ga) is one such element that can do this.

What is the finding?

We developed a method using ⁷¹Ga solid-state NMR spectroscopy with the world's highest-field magnet (at the MagLab) to study the number of oxygen ions around each gallium atom in electrolyte materials.

Why is this important?

The function of these materials is controlled by their defect chemistry. Our results clearly show gallium atoms bound to 4, 5, or 6 oxygen ions. This information will help design better electrolyte materials for solid oxide fuel cells.

Who did the research?

Lucia Corti¹, Ivan Hung², Amrit Venkatesh², Zhehong Gan², John B. Claridge¹, Matthew J. Rosseinsky¹, Frédéric Blanc¹

¹University of Liverpool (UK); ²National High Magnetic Field Laboratory

Why did they need the MagLab?

To see the different gallium sites in the ⁷¹Ga solid-state NMR spectrum, we need to use the world's highest magnetic field: the 36 Tesla Series Connected Hybrid magnet. This ultra-high field NMR platform provides a level of detail and spectral resolution that lower fields can’t, allowing us to determine the molecular structures of a wide range of advanced materials.

Details for scientists

View or download the expert-level Science Highlight, Probing the Chemistry of Fuel Cells with ⁷¹Ga NMR Spectroscopy
Read the full-length publication, Cation Distribution and Anion Transport in the La₃Ga_5-xGe_1+xO14+0.5x Langasite Structure, in Journal of the American Chemical Society

Funding

This research was funded by the following grants: K.M. Amm (NSF DMR-2128556); R.W. Schurko (NIH RM1 GM148766); F.Blanc (Leverhulme Research Centre for Functional Materials Design, EPSRC EP/T015063/1, EP/R029946/1)

For more information, contact Rob Schurko.