The Monolayer Dispersion Threshold Effect of CuO on Methanol Steam Reforming (MSR): Integrating Experimental and DFT Approaches to Design High-Performance Catalysts

To design highly efficient catalysts, it is of great importance to clarify the cofunctions of surface-active components. With the objective of developing more applicable catalysts for MSR to produce H₂, the Cu/CuO distribution on Zr-CeO₂ support and the Cu-support interactions have been analyzed according to the monolayer dispersion theory. It is discovered that CuO can disperse spontaneously with a monolayer dispersion capacity/threshold around 1.14 mmol/100 m² surface area (4.6 wt %). When CuO loading is below 4.6 wt %, CuO is highly dispersed in a submonolayer/monolayer state. At this state, XPS and DFT calculations have testified that there is a strong Cu-support interaction, which occurs mainly through electron donation from Cu, Ce, and Zr to O. The strong interaction can promote the active metallic Cu surface area after reduction and promote the generation of surface alkaline and active O₂^- sites, which is conducive to the reaction. The best promotional effect can be attained at the threshold. Based on the results, it is proposed that the optimal catalyst can be modulated controllably at the CuO monolayer dispersion capacity. In this work, DFT calculations have been introduced for the first time to verify the monolayer dispersion phenomenon.