A review of classical hydrogen isotopes storage materials

Hydrogen storage alloys (HSAs) are attracting widespread interest in the nuclear industry because of the generation of stable metal hydrides after tritium absorption, thus effectively preventing the leakage of radioactive tritium. Commonly used HSAs in the hydrogen isotopes field are Zr2M (M = Co, Ni, Fe) alloys, metallic Pd, depleted U, and ZrCo alloy. Specifically, Zr2M (M = Co, Ni, Fe) alloys are considered promising tritium-getter materials, and metallic Pd is utilized to separate and purify hydrogen isotopes. Furthermore, depleted U and ZrCo alloy are well suited for storing and delivering hydrogen isotopes. Notably, all the aforementioned HSAs need to modulate their hydrogen storage properties for complex operating conditions. In this review, we present a comprehensive overview of the reported modification methods applied to the above alloys. Alloying is an effective amelioration method that mainly modulates the properties of HSAs by altering their local geometrical/electronic structures. Besides, microstructural modifications such as nano-sizing and nanopores have been used to increase the specific surface area and active sites of metallic Pd and ZrCo alloys for enhancing de-/hydrogenation kinetics. The combination of metallic Pd with support materials can significantly reduce the cost and enhance the pulverization resistance. Moreover, the poisoning resistance of ZrCo alloy is improved by constructing active surfaces with selective permeability. Overall, the review is constructive for better understanding the properties and mechanisms of hydrogen isotope storage alloys and provides effective guidance for future modification research.