Dual Catalytic\nActivity of Pd-Dispersed MOF for Ammonia-Free\nHydrogen Generation from Ammonia Borane and Sodium Borohydride in\nAqueous and Methanol Solvents

The\ndevelopment of effective catalysts for hydrogen (H<sub>2</sub>) generation\nfrom chemical hydrides is essential for advancing hydrogen-based\nenergy technologies. Herein, we synthesized a Pd-dispersed CPO-27\ncatalyst exhibiting exceptional performance for hydrolysis of two\nboron-based chemical hydrides, i.e., ammonia borane (AB) and sodium\nborohydride (SB). The catalyst demonstrated activation energies of\n22.7 and 18.12 kJ mol<sup>–1</sup> for AB and SB hydrolysis\nrespectively, confirming its proficient catalytic activity. To comprehensively\nunderstand the factors influencing the production of H<sub>2</sub>, we systematically investigated the effects of the two hydrides\nand catalyst concentrations on H<sub>2</sub> evolution rates. Additionally,\nkinetic isotope effect studies were conducted to determine the rate-determining\nstep of hydrolysis reactions. The Pd@MOF catalyst can efficiently\ncapture released ammonia during AB hydrolysis, addressing a major\nlimitation of this process. Notably, the Pd@MOF catalyst demonstrated\nits catalytic compatibility with methanol solvent too, exploring its\napplicability in various reaction environments. Overall, our study\nhighlights the capability of the Pd@MOF catalyst toward H<sub>2</sub> release from diverse complex hydrides in different solvent systems\nfor H<sub>2</sub> generation in clean energy applications.