Mimicking Real Catalysts: Model Stepped Nickel Surfaces in Furfural Catalysis─Insights into Adsorption, Reactivity, and Defect-Driven Conversion Pathways.

The catalytic conversion of furanic compounds into renewable chemicals is essential for sustainable manufacturing. Here, we report a unique self-hydrogenation pathway of furfural to 2-methylfuran on Ni(119) surface, showing how steps and nickel carbides govern reaction selectivity. Thermal desorption and spectroscopic measurements reveal that furfural undergoes decarbonylation to furan on terraces, while step sites act as "hydrogen transfer pumps", abstracting hydrogen from furfural and facilitating its diffusion to terrace-bound molecules, thereby promoting selective hydrogenation to 2-methylfuran. Moreover, the surface-bound hydrogen enhances hydrogenolysis, with product selectivity closely connected to hydrogen concentration. DFT calculations show a preference for the top step edges, where strong bonding and electron redistribution stabilize intermediates and promote catalytic transformations. We further demonstrate how these insights provide a framework for designing advanced catalysts through surface structure optimization. By linking model catalysts with real-world applications, this approach enables the development of efficient and selective catalysts tailored for biomass conversion.