Order–disorder hybrid high-entropy Co–Cu-Fe–Mn–Ce oxides for photothermal CO2 hydrogenation

Abstract

CO₂ is a waste gas but also a crucial C₁ resource. Thus, the chemical conversion of CO₂ is significant for reducing its concentration in the air and mitigating its negative impacts on the environment. High-entropy oxides (HEOs) have recently attracted significant attention, especially in catalysis. In the present work, we developed high-entropy Co–Cu–Mn–Fe–Ce oxides via a simple sol–gel method combined with a calcination temperature control strategy, and the prepared samples were applied in photothermal catalytic hydrogenation of CO₂ to CO. The calcination temperature during the preparation of the catalyst significantly influenced its structure, resulting in different photoelectronic properties, CO₂/H₂ adsorption properties, and catalytic performances. Among the prepared samples, CoCuMnFeCeO_x calcinated at 500 °C, denoted as CoCuMnFeCeO_x(500), delivered high performance with a highest activity of 110 mmol g_cat⁻¹ h⁻¹ and a selectivity of 99.4%. Thus, the prepared high-entropy oxides have excellent catalytic activity and facilitate the conversion of CO₂. In situ DRIFTS and DFT calculations confirmed that the reaction generates a *COOH intermediate in the synthesis of the CO product, and the rate-determining step is related to the formation of *COOH from CO₂. The present work provides a promising approach for constructing efficient catalysts for CO₂ utilization and sheds light on developing a strategy for enhancing the catalytic efficiency of HEO samples.