Construction of Noble Metal-Loaded Functional Catalysts for Highly Efficient Catalytic Dehydrogenation of Ammonia Borane via Hydrolysis

Abstract

With the ever-growing research intereset in hydrogen storage materials, rationally designing suitable catalysts for ammonia borane (AB) hydrolysis and clarifying the catalytic mechanism remain essential and challenging. Herein, Ru, Pt and Pd were supported on the carriers with varying N contents via impregnation reduction with NaBH4. Kinetc isotope effect studies and a series of characterization methods were applied to explore the dehydrogenation mechanism, revealing that the cleavage of O-H in water is the rate-determining step (RDS) of the reaction. Owing to their electronic and anchoring effects, Ru-based catalysts exhibit high catalytic activity in AB dehydrogenation. Specifically, the optimal Ru/ZrN with an average particle size of 1.4 nm exhibits remarkable hydrogen evolution activity and turnover frequency (TOF=305.3 min-1) under ambient conditions, superior to the corresponding monometallic counterparts (i.e., Pd/ZrN and Pt/ZrN) and many previous reports. Apart from satisfactory durability, the optimal catalyst exhibits a remarkably low apparent activation energy (31.48 kJ/mol). This work elucidates how support nitrogen contents modulate the metal-support electronic interaction, thereby providing a strategy for designing high-performance catalysts and filling a knowledge gap in AB dehydrogenation mechanisms.