An InOx Surface Enrichment on the Cu Nanoparticles for the Methanol Steam Reforming

Abstract In the realm of heterogeneous catalysts promoted by indium, indium often covers other active metals, thereby compromising catalytic activity. However, the inhibition mechanism remains poorly understood. In this study, we investigate the interaction between copper (Cu) and indium oxide (InO x ), focusing on the role of the Cu−In interface during the methanol steam reforming (MSR) reaction. Utilizing a series of (quasi) in situ characterization techniques, we observe a decrease in intrinsic catalytic activity for MSR on the CuIn/Al 2 O 3 catalyst, which can be attributed to the surface enrichment of InO x on Cu nanoparticles. Moreover, our findings reveal that the enrichment suppresses both the dehydrogenation of *CH 3 O and the dissociation of H 2 O, ultimately leading to a reduction in catalytic activity. This discovery has the potential to guide the rational design of enhanced indium‐based catalysts in the future.