| 초록 |
The mechanism of catalytic non-electrochemical hydrogen peroxide direct synthesis (HPDS) from hydrogen and oxygen is conventionally considered as a Langmuir-Hinshelwood (LH) mechanism. A recent experimental study show that the conventional LH mechanism may not be true even on the most proto-typical HPDS catalyst: palladium (Pd) catalysts. In fact, it is proposed that the "non-electrochemical" HPDS is actually a heterolytic redox reaction of H2 and O2 forming H2O2 with proton-electron transfer on Pd surfaces. In this presentation, we provide a DFT model with accurate kinetics for the HPDS on Pd catalysts. We show that even with a more comprehensive model including solvation and free energy corrections, the LH mechanism fails to explain the experimental observations of HPDS. We then model the hetrolytic mechanism by combining the Butler-Volmer equation with the electrochemical constant-potential DFT to compare the kinetics of HPDS with the side reaction, H2O production. We prove that the heterolytic mechanism indeed explains experimental observations better than the LH mechanism, and that HPDS is kinetically favored than water production. |
