Advancements and challenges in sodium borohydride hydrogen storage: A comprehensive review of hydrolysis, regeneration, and recycling technologies

Hydrogen's potential as a clean energy carrier is increasingly recognized, but its storage remains a significant challenge. Sodium borohydride (NaBH4) stands out as an efficient hydrogen storage medium due to its high gravimetric capacity and safety profile. This review paper provides a comprehensive analysis of the research progress in NaBH4 hydrolysis for hydrogen production from 2004 to 2024. This paper discusses the advantages of NaBH4, including its high hydrogen yield, stability, controlled hydrogen release, and potential for regeneration into NaBH4 from the by-product sodium metaborate. This review surveys various catalysts used to enhance the hydrolysis reaction, such as cobalt, nickel, ruthenium, and noble metals, emphasizing their efficiency, recyclability, and economic viability. It also examines the influence of reaction conditions like temperature, pH, and NaBH4 concentration on the hydrolysis process. Additives and modifiers that improve reaction kinetics and hydrogen yield are also discussed. This paper further explores the regeneration and recycling of NaBH4, which is crucial for a sustainable hydrogen economy. It outlines three main approaches: thermochemical, mechanochemical, and electrochemical methods, each with its advantages and challenges. In conclusion, NaBH4 is a compelling hydrogen storage material with ongoing research aimed at overcoming the remaining challenges for its large-scale application. The development of more efficient and sustainable NaBH4 regeneration methods is essential for the future of clean energy.