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Highly ordered Pd/CeOx inverse opals for alkaline hydrogen oxidation
Michael Wilms1,2, Arma Musa Yau1,2, Ruby Susan Raju1
1Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg 412 96, Sweden. mathilde.luneau@chalmers.se.
Nanoscale
|May 7, 2026
Summary
Highly ordered palladium on ceria inverse opals boost alkaline hydrogen oxidation reaction (HOR) in fuel cells. Optimal pore size and interconnect thickness are key for enhanced HOR kinetics and mass transport, not just interfaces.
Area of Science:
- Materials Science
- Electrochemistry
- Catalysis
Background:
- Palladium supported on ceria (Pd/CeOx) is a promising electrocatalyst for the alkaline hydrogen oxidation reaction (HOR) in anion exchange membrane fuel cells.
- CeOx is proposed to enhance HOR kinetics via OH spillover and modulated Pd-H binding at the Pd-Ce interface.
Purpose of the Study:
- To maximize the Pd-Ce interfacial area using a novel synthesis method for Pd/CeOx inverse opals (IOs).
- To investigate the effect of tunable pore sizes (20-250 nm) and ordered pore networks on HOR activity and mass transport.
Main Methods:
- Synthesis of highly ordered Pd/CeOx inverse opals directly on glassy carbon electrodes with tunable pore sizes.
- Characterization of IO structure, including pore size, mesoporosity, and Pd-O-Ce interfacial sites.
- Electrochemical measurements to evaluate HOR activity, electrochemically active surface area (ECSA), and stability.
Main Results:
- IOs exhibited ordered pore networks, tunable pore sizes down to the mesoporous regime, and dispersed Pd species with Pd-O-Ce interfacial sites.
- HOR activity showed a pore size dependence, with IOs from 104 nm templates yielding the highest specific activity.
- Larger-pore IOs had reduced ECSA due to lower support conductivity; increasing Ce3+ or Pd-O-Ce content did not improve activity, indicating a balance is needed.
Conclusions:
- The inverse opal architecture effectively engineers Pd-Ce interfaces, but pore size and interconnect thickness are critical for enhanced HOR kinetics and mass transport.
- The synthesized Pd/CeOx IOs demonstrated structural stability and improved kinetics after 1000 cycles.
- This fabrication method enables the design of mesoporous bifunctional catalysts for fuel cells and electrolyzers.
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