Rational 3D Structure of Monolithic Catalysts for Enhanced Hydrolytic Dehydrogenation of Ammonia Borane

Monolithic catalysts have irreplaceable advantages inhydrogen(H-2) production through catalytic dehydrogenation fromliquid-phase hydrogen storage materials. However, monolithic catalystssuffer from an inevitable reduction in accessible active sites dueto the reduced specific surface area and hindered mass transfer. Therefore,a rational three-dimensional (3D) structure of monolithic catalystsis needed to adjust the structural factors for maximizing performance.Herein, a series of efficient and low-cost 3D catalysts with designedperiodic structures were successfully fabricated. Due to the optimizedspecific surface area and bubble transport of the elaborate 3D structure,compared to the disordered foam structure, the new series of monolithiccatalysts showed 2.3- and 1.6-fold improvement in overall catalyticperformance at 298 and 318 K without any change in physiochemicalcharacteristics, with hydrogen generation rates of 2548 and 3885 mLg(cat) (-1) min(-1), respectively.In addition, a three-period structural design philosophy for 3D catalystswas summarized, and the concept of surface activity was introducedto provide quantifiable criteria for guidance of structural optimization.The outcomes in this paper may open up new insights for building high-efficiencymonolithic catalysts. Dueto the advantages of high-efficient, low-cost 3D catalystswith designed structures in specific surface area and bubble transport,the new series of 3D catalysts show significant enhancement in overallcatalytic performance of ammonia borane at different H-2 evolution rates.