Ruthenium Nanoparticles RuNPs@[COK-12]─NH2 and RuNPs@[COK-12]─NH2-imid as Efficient Heterogeneous Catalysts for H2 Production from NaBH4 Hydrolysis

Abstract

The development of an efficient methodology for enhancing the catalytic efficiency toward hydrolysis of sodium borohydride (NaBH₄) is of vital significance but remains a long-standing challenge. In this work, RuNPs@[COK-12]─NH₂ 2a and RuNPs@[COK-12]─NH₂-imid 2b were synthesized and fully characterized by several analytical techniques. The supported RuNPs 2a and 2b catalyze the release of H₂ from NaBH₄ with remarkable proficiencies, and catalyst 2b was found to be more effective than its counterpart 2a. A TOF of 176.3 mole_H2.mol_cat⁻¹ min⁻¹ for 2b was attained when the hydrolytic reaction was conducted with a low catalyst loading of 0.1 mol%. The reaction kinetics investigations revealed that the hydrolysis is first order in catalyst and NaBH₄ with apparent E_a of 32.1 and 29.0 kJ mol⁻¹ for RuNPs catalysts 2a and 2b, respectively. The efficacy of RuNPs 2b for the hydrolysis of NaBH₄ showed that the catalytic process is significantly faster in H₂O than in D₂O with KIE k_H/k_D = 2.6. Furthermore, RuNPs 2b retains 80% of its initial catalytic activity after 5th cycles.