Ultrafine RhNi Nanocatalysts Confined in Hollow Mesoporous Carbons for a Highly Efficient Hydrogen Production from Ammonia Borane
Ren Wei, Zhichao Chen, Hao Lv, Xuecheng Zheng, Xin Ge, Lizhi Sun, Kai Song, Chuncai Kong, Wei Zhang, Ben Liu
Abstract
Ammonia borane (AB) has received growing research interest as one of the most promising hydrogen-storage carrier materials. However, fast dehydrogenation of AB is still limited by sluggish catalytic kinetics over current catalysts. Herein, highly uniform and ultrafine bimetallic RhNi alloy nanoclusters encapsulated within nitrogen-functionalized hollow mesoporous carbons (defined as RhNi@NHMCs) are developed as highly active, durable, and selective nanocatalysts for fast hydrolysis of AB under mild conditions. Remarkable activity with a high turnover frequency (TOF) of 1294 molH2 molRh–1 min–1 and low activation energy (Ea) of 18.6 kJ mol–1 is observed at room temperature, surpassing the previous Rh-based catalysts. The detailed mechanism studies reveal that when catalyzed by RhNi@NHMCs, a covalently stable O–H bond by H2O first cleaves in electropositive H* and further attacks B–H bond of AB to stoichiometrically produce 3 equiv of H2, whose catalytic kinetics is restricted by the oxidation cleavage of the O–H bond. Compositional and structural features of RhNi@NHMCs result in synergic electronic, functional, and support add-in advantages, kinetically accelerating the cleavage of the attacked H2O (O–H bond) and remarkably promoting the catalytic hydrolysis of AB accordingly. This present work represents a new and effective strategy for exploring high-performance supported metal-based alloy nanoclusters for (electro)catalysis.