Thermal decomposition mechanisms of methanol, ethanol, and 1-propanol on the Si(100)-2 × 1 surface

The thermal decomposition mechanisms of chemisorbed methanol, ethanol, and 1-propanol on Si(100)-2 × 1 surface were theoretically investigated. Five different hydrogen elimination channels were found, which are one α-hydrogen elimination, two different β-hydrogen eliminations, and two different γ-hydrogen eliminations. They produce aldehyde, epoxide, alkene, oxetane, and cyclopropane as desorbing species, respectively. Among these, the α- and the β-hydrogen eliminations producing aldehyde and alkene are kinetically the most favorable. In addition, Si-O bond formation and molecular hydrogen desorption channels were also found to yield methane and molecular hydrogen as the final outcomes, respectively. On the basis of these results, new assignments for the previous experiments are suggested. Current theoretical study illustrates that thermal decompositions of adsorbed primary alcohol are the result of various competing reactions, and the particular position of hydrogen on alcohol plays a major role in the overall surface reactivity.