Unravelling the reaction mechanism of gas-phase formic acid decomposition on highly dispersed Mo2C nanoparticles supported on graphene flakes

Mo2C/graphene nanostructures were used to investigate the nature of gas-phase formic acid decomposition into either CO/H2O or CO2/H-2 products. The experimental data show that the Mo2C/graphene can facilitate both decarboxylation and dehydration pathways for the formic acid decomposition reaction. Its selectivity is strongly influenced by the reaction temperature where the decarboxylation predominates at a low temperature (e.g., <= 280 degrees C) and the dehydration predominates at a high temperature (e.g., >= 370 degrees C). These experimental data are compared to Monte Carlo simulations. It was found that the decarboxylation pathway for the production of CO/H2O can be simulated and explained by an Eley-Rideal type mechanism that involves interaction of gas-phase HCOOH with surface H*. Furthermore, the dehydration pathway for the production of CO2/H-2 can be simulated and explained by a Langmuir-Hinshelwood type mechanism that involves unimolecular decomposition of surface HCO*O* to form CO2 and H*.