Utilization of high entropy alloy (Co-Cu-Fe-Mn-Ni) and support (CeO2) interaction for CO2 conversion into syngas

Abstract

Here metal support interaction (MSI) is demonstrated in a high entropy alloy (HEA: CoCuFeMnNi) supported CeO2. The HEA behaves as an active dry reforming catalyst only when it is supported over CeO2 oxide, clearly demonstrating MSI. Based on spectroscopic and microscopic observations, it is envisaged that the substitutional effect is the one that causes the lattice oxygen activation, an important active species during DRM reaction. Transient studies are performed to understand the surface chemistry of the interaction between methane and CO2 in the presence of a catalyst, which results in a methane decomposition first to generate hydrogen and carbon and followed by a CO2 reaction to give CO using deposited carbon. The experimental observations are further proven by mechanistic study with DFT calculations which show a major contribution of H-assisted CO2 dissociation and pre-H2 releasing carbon depositing CH4 dissociation and a minor contribution of pre-CO releasing H2 formation. This MSI moves the d-band center of the Co atoms of CoCuFeMnNi/CeO2 to the closest position of the Fermi level as compared to the isolated nanoparticles. This study can be taken as a proof of concept to demonstrate that MSI can be generated in the HEA/CeO2 catalysts for a generic heterogeneous gas phase reaction.