Optimizing the Surface Coordination of Pd-Cu Nanoalloy Through Chemical Ordering to Enhance Hydrogenation Selectivity AITranslate

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Precise control of chemical ordering in bimetallic nanocatalysts offers a route to decouple activity and selectivity in acetylene hydrogenation, but direct atomic-scale evidence linking surface order to catalytic performance is scarce. Here, we tune Pd-Cu nanoalloys from chemically disordered to highly ordered states by composition control and targeted H2 thermal treatment. Under near-industrial conditions, all catalysts reach full acetylene conversion between 100°C and 120°C, whereas the ethylene selectivity enhances with the chemical ordering increasing. By combining synchrotron X-ray absorption fine structure (XAFS) with X-ray total scattering and reverse Monte Carlo (RMC) simulation, three-dimensional atomic models are reconstructed to quantitatively map surface coordination. Compared with the chemically disordered Pd-Cu nanocatalyst, the highly ordered PdCu shows an increase in average surface Pd-Cu coordination and an expansion of mean surface Pd-Pd separations. These structural features weaken ethylene binding and suppress re-adsorption, rationalizing the enhanced selectivity. Our study provides direct atomic-scale evidence connecting chemical order to catalytic selectivity and opens the way for guiding the precise design of bimetal nanocatalysts.