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

This article provides a comprehensive review of sodium borohydride (NaBH₄) as a hydrogen storage material, focusing on its hydrolysis for hydrogen production and regeneration methods from 2004 to 2024. NaBH₄ offers advantages such as high gravimetric hydrogen capacity (~10.6 wt.%), stability, controlled hydrogen release, and the potential for recycling from its hydrolysis by-product sodium metaborate (NaBO₂). The review details various catalysts—including cobalt, nickel, ruthenium, iron, noble metals, and metal-free carbon-based materials—that enhance hydrolysis efficiency, discussing their activity, cost, recyclability, and challenges. It also examines key reaction parameters (temperature, pH, NaBH₄ concentration) and additives that influence hydrogen generation kinetics. Finally, the article evaluates three main NaBH₄ regeneration approaches—thermochemical, mechanochemical, and electrochemical—highlighting their respective benefits and limitations for sustainable, large-scale hydrogen storage applications.