To explore the enhanced coking stability of Pt-based catalysts doped with Ge (Figs. and), we used DFT to examine a single ethylene bound on Pt7, Pt7Ge2, and Pt7Ge2C2, including the GM, LM1 and LM2 isomers (Fig. ). Unique binding modes (20 for Pt7, 30 for Pt7Ge2, and 40 for Pt7Ge2C2) were characterized for each isomer, and the thermodynamically most stable structures are shown in Fig. , including the ethylene binding energies (ΔEC2H4) and the lowest C-H activation barrier energies (ΔE(C-H)). The ΔEC2H4 on pristine α-alumina was also calculated to be approximately -0.75 eV (Fig. ).