Understanding Methanol Coupling on SrTiO₃ from First Principles

Perovskites are interesting materials for catalysis due to their great tunability. However, the correlation of many reaction processes to the termination of a perovskite surface is still unclear. In this study, we use the methanol coupling reaction on the SrTiO₃(100) surface as a probe reaction to investigate direct C-C coupling from a computational perspective. We use density functional theory to assess methanol adsorption, C-H activation, and direct C-C coupling reactions on the SrTiO₃(100) surface of different terminations. We find that, although methanol molecules dissociatively adsorb on both A and B terminations with similar strength, the dehydrogenation and C-C coupling reactions have significantly lower activation energies on the B termination than on the A termination. The predicted formation of methoxy and acetate on the SrTiO₃(100) B termination can well explain the ambient-pressure XPS data of methanol on the single-crystal SrTiO₃(100) surface at 250 °C. This work suggests that a choice of B termination of perovskites would be beneficial for the C-C coupling reaction of methanol.