Metal-Free Supramolecular Catalytic Hydrolysis of Ammonia Borane through Cucurbituril Nanocavitands

Abstract

Ammonia borane (AB) is considered a potential “on-board” hydrogen storage material. However, its implementation as a hydrogen reservoir in fuel cells is lacking due to the extremely slow release of hydrogen at room-temperature hydrolysis. In this study, a metal-free supramolecular strategy is demonstrated at room temperature to increase the hydrolysis rate and yield of hydrogen along with significant reduction in ammonia release by using cucurbit­[5/8]­uril (CB5/CB8) nanocavitands as catalysts. The complex of AB with CB stabilizes the ammonium ion at the host portals, which reduces ammonia release and enhances hydrogen yield. The complexation brings down the activation energy of hydrolysis from 103.8 to ∼27.5 kJ mol–1 (for CB5), a value close to the Pt/Pd nanoparticle-based catalysts reported so far. The high catalytic performance and reusability of CB catalysts at very low concentration make AB a promising supramolecular alternative for a sustainable “on-board” energy source.

Maximizing Metal–Support Interactions in Pt/Co3O4 Nanocages to Simultaneously Boost Hydrogen Production Activity and Durability

“…Hydrogen is considered to be a key component of the near-future carbon-neutral energy portfolio. − Hydrogen storage, however, remains a major problem to the whole chain of hydrogen economy. Ammonia borane (AB, NH 3 BH 3 ) has aroused widespread research interest as a hydrogen carrier due to its high hydrogen capacity (19.6 wt %), long-term stability, and easy H 2 release. − These advantages make AB particularly attractive for automotive applications. Rapid H 2 release from AB can be achieved under mild conditions in the presence of catalysts.…”

Maximizing hydrogen production by AB hydrolysis with Pt@cobalt oxide/N,O-rich carbon and alkaline ultrasonic irradiation

“…1,2 The demand for clean energy without environmental impacts requires the development of renewable and sustainable energy sources. [3][4][5] Hydrogen has gained great interest as a globally recognized clean energy carrier. [6][7][8][9][10] However, hydrogen storage and controllable release remain a formidable challenge to achieving hydrogen economy.…”

Binding of toluidine blue-myristic acid derivative to cucurbit[7]uril and human serum albumin: computational and biophysical insights towards a biosupramolecular assembly

“…They have a highly hydrophobic cavity and two identical entry portals with high electron density from the surrounding carbonyl groups. 21,22 Recent interesting work involving CB[ n ]s include control of viscoelasticity of polymeric networks, 23 metal-free supramolecular catalysis and nanosheets/Pt nanoparticles for hydrogen generation, 24,25 among others.…”