X-ray vision
The team combined X-ray imaging with simulations to look inside the porous structures. This provided them unprecedented access to observe gas bubble behaviour over time, without taking the cell apart.
“If you want to generate green hydrogen at a mass scale, you need to make sure it’s first economically viable. One of the challenges the industry is facing is limitations in mass transport,” says Prof. Mostaghimi.
“When water is split, we found tiny hydrogen and oxygen bubbles get trapped inside the electrode, blocking the reaction sites and slowing the movement of water and ions, effectively starving the catalyst of fresh water.
“We looked at the architecture of these porous materials and found that a highly ordered, uniform pore structure resulted in minimal gas trapping.
“This tells us that the pore structure is directly linked to gas trapping, which gives manufacturers a pathway to designing more efficient systems.”
It was also the first time operando synchrotron imaging, coupled with state-of-the-art pore-scale numerical methods, had been used to visualise hydrogen bubble formation, growth, and accumulation during electrolysis.
“Before this, scientists couldn’t really see what was happening inside the electrode the way we could using our advanced technologies,” says Professor Ryan Armstrong, a co-investigator from UNSW School of Civil & Environmental Engineering.
“This work shows that mass transport limitations are fundamentally linked to electrode architecture, not just catalytic activity,” says Dr Ying Da Wang, who led the flow simulation and analysis from UNSW School of Minerals & Energy Resources Engineering.
“By combining real-time imaging, advanced two-phase flow simulations, and performance measurements, we now understand how the accumulation of hydrogen bubbles influences performance during water electrolysis,” says Dr Quentin Meyer, who, with Professor Chuan Zhao, contributed the electrochemistry expertise from the UNSW School of Chemistry.
Next steps
The researchers are now extending their focus to the techno-economic assessment of coupling green hydrogen production with transport and large-scale storage in underground porous reservoirs.
“A clean hydrogen economy depends on getting every link in the chain right,” says Prof. Mostaghimi.
“By looking at production, transport, and underground storage together, we can show policymakers and industry what is actually feasible, and at what cost.”
