Self-foaming Fe–Sn powder beds for durable hydrogen storage and release

Abstract

Abstract Hydrogen storage and release via redox cycling of oxide-metal powders offers advantages in safety and scalability as compared to pressurized tanks, but long-term storage capacity loss due to sintering and densification of powder beds remains a major challenge. In this work, we demonstrate that a transient liquid-phase swelling effect, triggered by the addition of a low-melting element to a high-melting powder bed, can effectively preserve powder-bed porosity and reactive surface area during extended redox cycling. By incorporating up to 40 at. % Sn into Fe powder beds, we induce a self-foaming behavior that counteracts powder densification and enables stable hydrogen storage/release performance over 50 redox cycles at 650 ºC. In situ X-ray diffraction and thermodynamic analysis reveal that both the added Sn and the resulting Fe-Sn intermetallic phase undergo reversible transformations throughout cycling, helping maintain high hydrogen storage/release capacity. Microstructural analysis shows that the continuous formation of “liquid-depletion porosity” at former Sn powder sites and the volumetric expansion of solid particles from imbalanced diffusion contribute to the retention of a porous architecture. This strategy achieves a hydrogen capacity of up to 261 mL/g, which is 22 times higher than that of pure Fe after 50 redox cycles. It provides a new materials design approach for durable metal/oxide systems in hydrogen storage, with other potential applications in solar thermochemical water splitting, carbon dioxide utilization,and chemical looping technologies.

The authors' abstract, as published at the source. Materials Today, 2026 · DOI ↗