The Unique Factor Governing Atomistic Rh-Catalyzed Dehydrogenation of CH₄

We uncovered that the valence density-of-states (DOS) gain, denoted as polarity (), of the catalyst Rh- uniquely governs the efficiency of CH4 dehydrogenation based on quantum computations of CH4-Rh(111;100) surfaces with and without Rh1 adatoms and Rh0 vacancies. Atomic undercoordination shortens the ligand-catalyst distance, transforming the undercoordinated Rh into a dipole Rh- species that forms the Rh-:H+-C- coupling bonds, where “:” denotes the electron-rich pole. The Rh-:H+ attraction and Rh-:C- repulsion shorten the RhP:H distance and elongate the H-C bond. The extents of Rh-:H-C segmental relaxation, catalyst valence band upward shift, and adsorption energy all vary exponentially with . The adsorption energy follows the order: Rh30(111) > Rh1/Rh(111) > Rh10(100) > Rh1/Rh(100) > Rh10(111) > Rh(100) > Rh(111) order, highlighting the significance of the dipolar coordination configuration. These findings should apply to undercoordinated catalytic reactions where the electric field of the dipolar catalyst plays a key role.