Ultrafine Ru nanoparticles anchored on core–shell structured zeolite-carbon for efficient catalysis of hydrogen generation

As a promising route to hydrogen production, hydrolysis of ammonia borane (AB) aqueous solution requires efficient and stable catalysts. In this paper, a carbon-coated zeolite is prepared by high temperature calcination using glucose as carbon source. Ultrafine Ru nanoparticles are anchored on the composite support with core–shell structure using a simple in situ reduction method. The prepared catalyst expressed outstanding catalytic activity in the hydrolytic dehydrogenation of AB. The effects of support prepared by different synthesis parameters on the performance of catalyst are investigated. The Ru/S-1@C(RSC-2) catalyst exhibited the highest catalytic activity for hydrolytic dehydrogenation of AB with a turnover frequency of 892 min⁻¹ at room temperature. This performance is superior to that of many catalysts previously reported. The excellent catalytic activity is attributed to the carbon layer on catalyst surface effectively limiting the aggregation of Ru nanoparticles in the hydrolysis reaction. The zeolite also plays a role in pre-activation of water. This pre-activation accelerates the rate-limiting step of water dissociation in the reaction. The kinetic studies for determining the activation energy (E_a = 36.8 kJ⋅mol⁻¹) were based on reaction temperature. The effects of catalyst concentration, AB concentration and NaOH concentration on hydrolysis rate of AB were further investigated. The high-performance catalysts and the preparation method in this study have wide application prospects in the field of clean energy.