Ultrasmall bimetallic Ru-Co alloy nanoclusters immobilized in amino-functionalized UiO-66 and N-doped carbonaceous zirconium oxide nanocomposite for hydrogen generation

To satisfy global energy demands and maintain sustainable levels of atmospheric greenhouse gases, alternative energy sources are required. H2 generation from hydrolysis of NaBH4 represents as a safe and convenient method for storing and releasing H2. The free amine groups (NH2) and the big pores in the NH2-UiO-66 metal-organic framework were exploited to encapsulate ultrasmall bimetallic Ru-Co alloy nanoclusters and monometallic Ru and Co nanoclusters with an average particle size of 1.5 nm via direct anionic exchange technique. To prove the role of the NH2 groups and the MOF’s pores in the creation of a well and uniform-dispersed ruthenium and cobalt nanoclusters, the NH2-UiO-66 was calcined at 600 °C for 3 h in the air to prepare N-doped carbonaceous ZrO2 (ZrO2N @ C) nanocomposite. Hydrazine hydrate (HH) was used as a reducing agent in the presence of microwave irradiation (MWI). The prepared catalysts were used as novel catalysts for hydrogen generation, via the hydrolysis of sodium borohydride (NaBH4). 2 wt% Ru-Co/NH2-UiO-66 displays a high hydrogen generation rate (HGR) of 10526 mL H2 g−1 min−1 from low concentration NaBH4 solution (50 mM). The extraordinary catalytic activity of the prepared catalysts attributes to the ultrasmall particle size of the ruthenium and cobalt nanoclusters in the MOF’s pores, the synergistic harmony between the Ru and Co nanoclusters in the alloy form, and the large surface area of the NH2-UiO-66. The effect of the NaBH4 concentration, catalyst amount, and reaction temperatures (30–60 °C) was investigated. The catalyst shows high recyclability efficiency for at least five cycles, due to the high leaching resistance of the alloy nanoclusters within the MOF host. The prepared catalysts may be considered as highly efficient catalysts for energy-based applications.