A Review on Catalytic Hydrolysis of Ammonia Borane for Hydrogen Production

Ammonia borane (NH3BH3, AB) is recognized as a promising hydrogen carrier due to its high hydrogen storage density (146 gL−1, mass fraction 19.6%), safety, non-toxicity, and high chemical stability. The hydrolysis of AB has also become a research hotspot in recent years and offers a viable route for hydrogen production. However, the practical application of AB hydrolysis encounters substantial challenges, including undefined catalytic mechanisms, suboptimal catalytic performance, and intricate issues in AB regeneration. Thus, elucidating catalytic mechanisms, developing highly efficient catalysts, and exploring effective regeneration methods for NH3BH3 are critical and urgent. This paper delves into the catalytic hydrolysis process of AB, detailing the mechanisms involved, and simplifies the steps that affect AB hydrolysis activity into the adsorption, activation, dissociation of reactants, and the formation and desorption of H2. It discusses the structural characteristics of metal catalysts used in recent studies, assessing their performance through metrics such as turnover frequency (TOF), activation energy (Ea), and reusability. On this basis, this paper conducts a relatively comprehensive analysis and summary of the strategies for optimizing the performance of AB hydrolysis catalysts, including three aspects, focusing on optimizing the number and dispersion of active centers, enhancing reactant adsorption and activation, and facilitating hydrogen desorption. In addition, it also addresses strategies for controlled hydrogen release during AB hydrolysis and methods for regenerating AB from spent solutions. Finally, corresponding conclusions and prospects are proposed, to provide a certain reference for the subsequent development of safe and efficient catalysts and research on the catalytic mechanism of AB hydrolysis.