A DFT/EDA study of ethanol decomposition over Pt, Cu and Rh metal clusters

Abstract Ethanol reforming has emerged in the last decades as a powerful solution for the energy problem, providing a way for hydrogen production from a renewable and environmentally friendly source. In the search for the best catalyst for this process, it is crucial to understand the reaction mechanism in all its details. In this work, we compare the reaction mechanism for the ethanol decomposition over Pt, Cu and Rh. The approach presented here involves the use of metal clusters treated by effective core potential basis set and the remaining species treated with all electrons. DFT calculations (B3LYP-D3) were used to construct the potential energy surface for all the steps in the path from ethanol to CH4, CH3CH3 and CH2CH2. Canonical molecular orbital energy decomposition analysis (CMOEDA) was used to understand the distinct behavior of the three metals. After the formation of acetaldehyde, the reaction over Pt and Rh easily continues towards the C–C bond breaking, which is much more difficult for Cu. The better capability of Pt and Rh to stabilize transition states is, in most cases, explained by a more malleable electron density in these clusters. This malleability allows the clusters to adjust the electron density to better deal with charge transfers taking place throughout every reaction step.