From Molecular Property to Catalytic Mechanism: A DFT Study on the Formation of High-Density cis-syn-cis-Perhydrophenanthrene

Abstract

High energy density fuels are crucial for advancing aerospace propulsion technologies. Perhydrophenanthrene is a promising high energy density fuel candidate owing to its polycyclic structure; however, a systematic evaluation of its properties and the understanding of its formation mechanism remain inadequate. This study addresses this gap via a comprehensive computational investigation that bridges molecular property screening with catalytic mechanism elucidation. First, key propertiesincluding density, specific impulse, and volumetric net heat of combustion-of six perhydrophenanthrene isomers were evaluated. The results identify cis-syn-cisperhydrophenanthrene as the isomer with the highest density. Subsequently, the formation mechanism of this optimal molecule was investigated on Ni(100) and Ni(111) surfaces using DFT calculations. The Ni(111) surface was determined to be the dominant surface for the formation of cis-syn-cis-perhydrophenanthrene due to its lower hydrogenation energy barrier. Fundamental electronic structure analysis revealed that the superior activity of Ni(111) originates from its lower-lying d z 2 orbital energy level, which fine-tunes the adsorbate-substrate interaction by reducing electron transfer from phenanthrene. This results in a more favorable adsorption strength for 2 hydrogenation, consistent with the Sabatier principle. This work establishes a complete framework spanning from property-based screening to mechanistic understanding, not only confirming cis-syn-cis-perhydrophenanthrene as an excellent high energy density fuel candidate but also providing atomic-level insights into its formation mechanism.The findings offer valuable guidance for further research on phenanthrene hydrogenation.