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The dehydrogenation mechanisms of ethylene diamine monoborane (EDMB) adducts and its derivatives having CH 3 , Cl, F, NH 2 , OCH 3 , CN, and H substituents at two sites on the ethylene backbone were investigated to explore their potential as liquid organic hydrogen carriers (LOHCs). Using density functional theory calculations, the thermodynamic parameters of the EDMB adducts and dehydrogenation reactions to form cyclic monomers, dimers, and trimers were calculated. In particular, we focused on the free energy barriers of EDMB adducts substituted with Cl/CN, Cl/OCH 3 , F/CN, F/OCH 3 , F/F, and NH 2 /H for cyclic monomer formation, H/CH 3 , H/CN, Cl/H, and NH 2 /H for cyclic dimer formation, and H/Cl, H/F, and NH 2 /H for cyclic trimer formation, which are promising candidates for chemical hydrogen storage. We also explored the formation of cyclic trimers from the selected cyclic monomers with CH 3 /CH 3 , H/CH 3 , and NH 2 /H substituents. As a result, the dehydrogenation pathways and transition states of the various adducts for the formation for the various cycles were identified, and electrostatic potential surfaces and frontier molecular orbitals calculations were calculated to understand the reaction further. The results obtained indicate the potential of these materials for hydrogen storage, and we hope that this work will encourage the experimental investigation of these materials. Image 1 • Amine–boranes studied as potential liquid organic hydrogen carriers. • Amine–borane adducts undergo dehydrogenation via cyclization. • Substituent electronic and steric effects alter reaction energetics. • Electronegative substituents (Cl, CN, and F) result in favorable dehydrogenation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrochemical reduction of CO 2 on Cu(1 1 1) surface and Cu/G catalysts. • The potential-limiting step (E barr) strongly prefers the favorable (COOH/HCOO) pathways. • Electronic properties and binding nature explains the reason for selective end products. • Graphite-supported single atom copper catalyst (Cu/G) prefers CH 3 OH as final end product. First-principles study explores the catalytic performance of the Cu(1 1 1) and Cu/G catalysts for the electrochemical CO 2 reduction using computational hydrogen electrode model. Two different pathways, determined based on the initially generated intermediates (COOH* and HCOO*), as well as successive intermediates and the end products, were investigated. Although the two catalysts promote both pathways, Cu(1 1 1) surface favors "COOH pathway" and Cu/G catalyst strongly promotes the "HCOO pathway" with an free energy barrier of 0.83 eV (CO* → CHO*) and 0.87 eV (HCOO* → H 2 COO*). Electronic properties and binding nature of the final intermediate (CH 3 O*) on both catalysts sheds light on the fundamental reason for the selective end products (CH 4 on the Cu(1 1 1) surface and CH 3 OH on the Cu/G catalyst). CH 3 OH is predominantly produced with the Cu/G catalyst because the C O bond of CH 3 O* is stronger than the bond between the single Cu atom and O of CH 3 O*, given that the energy of the d-band center of the single Cu atom is relatively highly negative. The current study explores the different electrochemical reduction pathways on the Cu(1 1 1) and Cu/G catalyst, providing insight for the design of highly efficient catalysts that afford selective end products. [ABSTRACT FROM AUTHOR]