Efficient hydrogen evolution at Ni/CeOx interfaces in anion-exchange membrane water electrolysers

A macro/mesoporous film with Ni/CeO_x interfaces is designed via the dynamic hydrogen bubble template (DHBT) method for ampere-level production of hydrogen in anion exchange membrane water electrolysers (AEMWEs). The AEMWE achieves leading energy efficiencies of 95% and 80%, based on the higher and lower heating values of hydrogen, respectively, at 0.25 A cm⁻², producing hydrogen at 42 kW h kg⁻¹ and a cost of $0.84 per kg, thereby meeting the U.S. Department of Energy (DOE) price target ($1 per kg) for 2030. A current density of 5 A cm⁻² is achieved at 2.08 V and 60 °C in the AEMWE, with overall cell activation and concentration overpotentials of 594 mV, establishing a leading position in the field. The Ni/CeO_x catalyst exhibits superb hydrogen evolution reaction (HER) activity by delivering 1 A cm⁻² at an overpotential of 201 mV at 20 °C, far surpassing Ni, CeO_x, and benchmark Pt/C catalysts. Electrochemical and theoretical calculations reveal accelerated charge transfer due to the preferential adsorption of intermediates at the tailored defective interfaces during hydrogen evolution. Hydrogen evolving during electro-deposition forms 3D channels for bubble removal in the AEMWE, akin to a hydrogen memory, speeding up mass transfer.