Dual Catalytic Activity of Pd-Dispersed MOF for Ammonia-Free Hydrogen Generation from Ammonia Borane and Sodium Borohydride in Aqueous and Methanol Solvents.

The development of effective catalysts for hydrogen (H2) generation from chemical hydrides is essential for advancing hydrogen-based energy technologies. Herein, we synthesized a Pd-dispersed CPO-27 catalyst exhibiting exceptional performance for hydrolysis of two boron-based chemical hydrides, i.e., ammonia borane (AB) and sodium borohydride (SB). The catalyst demonstrated activation energies of 22.7 and 18.12 kJ mol-1 for AB and SB hydrolysis respectively, confirming its proficient catalytic activity. To comprehensively understand the factors influencing the production of H2, we systematically investigated the effects of the two hydrides and catalyst concentrations on H2 evolution rates. Additionally, kinetic isotope effect studies were conducted to determine the rate-determining step of hydrolysis reactions. The Pd@MOF catalyst can efficiently capture released ammonia during AB hydrolysis, addressing a major limitation of this process. Notably, the Pd@MOF catalyst demonstrated its catalytic compatibility with methanol solvent too, exploring its applicability in various reaction environments. Overall, our study highlights the capability of the Pd@MOF catalyst toward H2 release from diverse complex hydrides in different solvent systems for H2 generation in clean energy applications.