Sustainable hydrogen production via CO2-assisted BH3 + BH3 reaction: a computational analysis.

The activation and utilization of carbon dioxide (CO2) for hydrogen production represents a central challenge in the development of sustainable and carbon-neutral energy systems. Borane (BH3), a potent Lewis acid with high reactivity toward small molecules, has emerged as a promising candidate for CO2 activation and hydrogen release. However, the mechanistic effects of incorporating multiple CO2 molecules into BH3-based systems remain poorly understood. In this study, density functional theory (DFT) calculations were conducted to explore the reaction mechanisms of a dimeric BH3 system in the presence of zero to three CO2 molecules. Potential energy surfaces were constructed at the M06-2X/6-311++G(3df,2p) level to identify key intermediates, transition states, reaction energies, and activation barriers. The computational results reveal a stepwise mechanism involving BH3-CO2 adduct formation and distinct transition states, with CO2 playing a significant role in modulating both thermodynamic stability and kinetic accessibility. Notably, the inclusion of CO2 stabilizes multi-component complexes and lowers activation barriers, thereby facilitating hydrogen release. These findings underscore the dual function of CO2 as both a structural stabilizer and an energetic facilitator, offering valuable insights into CO2 valorization and hydrogen generation in the context of sustainable energy applications.