Mechanistic insights into H2 evolution via water splitting at the expense of B2(OH)4: a theoretical study

Abstract

H₂ has been comprehensively deemed a promising potential candidate to replace traditional fossil fuel-based energy. Typically, the hydrolysis of most hydrogen-rich boron hydrides (e.g. NaBH₄, NH₃BH₃ and Me₂NHBH₃) catalyzed by nanomaterials generates H₂ with only one H atom supplied by water and the other one by a hydrogen-rich boron hydride. Interestingly, both H atoms of produced H₂ are provided by water upon hydrolysis of B₂(OH)₄. Herein, the catalytic mechanisms of H₂ evolution upon water splitting at the expense of B₂(OH)₄ in its hydrolysis reactions catalyzed by acid, base or metal nanoparticles have been investigated by density functional theory (DFT) calculations. By computational studies, the mechanisms of catalysis by base and metal nanoparticles are basically the same as those speculated from our previous experiments. The previously proposed acid catalytic mechanism has been overturned, however. This study not only provides important insights into the catalytic mechanism for water splitting at the expense of B₂(OH)₄, but also opens up an exciting opportunity to use water to store H₂.