Sub-2 nm Ternary Metallic Alloy Encapsulated within Montmorillonite Interlayers for Efficient Hydrogen Generation from Ammonia Borane Hydrolysis

Abstract

Ultrafine metal alloy nanoparticles are emerging as highly effective catalysts for the generation of hydrogen from ammonia borane (AB) hydrolysis. The fabrication of multimetallic alloys with high activity, stability, and metal utilization remains the biggest challenge. Herein, sub-2 nm ternary Rh–Ru–Ni alloys were encapsulated within the interlayers of layer-stripped montmorillonite (MMT) via a simple impregnation method. Experiment and theory results revealed that the synergistic effect of the trimetallic alloy significantly lowers the energy barrier for the AB hydrolysis reaction, by boosting the adsorption and O–H dissociation of H₂O molecules. The optimized Rh_0.8Ru_0.2Ni_0.25@MMT-S catalyst achieves high turnover frequency values of 2961 and 784 min^–1 at 298 and 273 K, respectively, as well as high recycling stability and thermal resistance. Moreover, the encapsulation method has versatility and can be also applied to synthesize ultrafine Pt- and Ir-based nanoparticles. This study not only highlights the role of the synergistic effect in trimetallic alloys for improving hydrogen evolution but also offers a route to design highly efficient and stable metal nanocatalysts for other applications.