Self-Reconstruction Mechanism of High-Entropy Oxide in Glycerol Steam Reforming: The Key to H2-rich Syngas Production

Known for its tunable catalytic properties, high-entropy oxide (HEO) is a promising candidate to achieve stable catalytic performance in thermochemical reforming processes. However, the catalytic mechanism of the polymetallic components has not yet been revealed. This work reports the catalytic mechanism of HEO in H₂-rich syngas production from glycerol steam reforming (GSR). A La₂CaNiCoMn HEO was rationally designed based on the different functions of the metal components. It was interesting that self-reconstruction was discovered for HEO during the initial stage of the GSR, which was the key to efficient H₂ production. NiCo nanoalloy emerged to form a supported-like NiCo/HEO structure with the induction of oxygen lattice consumption, leading to the increasing H₂ production rate as the HEO reconstruction proceeded. Segregation energies and M-O bond energies were calculated to further understand the metal exsolution mechanism. The synergistic catalytic effect of the polymetallic components on HEO was analyzed in various aspects by multiscale characterization combined with DFT simulation calculation. The high-temperature-stable catalytic performance was due to the coke precursor formation being inhibited and the strong interaction between NiCo and the parent HEO.