Utilization of High Entropy Alloy (Co–Cu–Fe–Mn–Ni) and Support (CeO2) Interaction for CO2 Conversion into Syngas

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.