Efficient Hydrogen Generation from Ammonia Borane and Tandem Hydrogenation or Hydrodehalogenation over AuPd Nanoparticles

Alternatives to the use of pressurized hydrogen (H-2) in chemical syntheses are of growing interest and importance in developing safer protocols. Ammonia borane (AB), with its high hydrogen content and ability to release H-2 under mild conditions, is one potential solution. However, optimization of AB dehydrogenation and further the use of AB as a H-2 source to facilitate tandem one-pot reactions with both high activity and stability is an ongoing research challenge. In this work, monodisperse AuPd nanoparticle (NP) catalysts were synthesized and systematically studied for AB dehydrogenation, and Au-rich NPs were found to be the most active composition for AB methanolysis with a turnover frequency (TOF) of 160 min(-1) surpassing most Pd-based NP catalysts to date. More importantly, Au-rich NPs were also active in the one-pot tandem reduction of a series of nitro-groups and the hydrodehalogenation of mono- and polyhalogenated persistent chemical pollutants under mild reaction conditions using only a 2:1 molar ratio of AB to substrate. The AuPd catalyst was stable after ten reaction runs for AB methanolysis and five reaction runs for tandem one-pot reactions without a loss of activity or change in NP structure and morphology.