Reduction‐driven fermi‐level equilibration for electron modulation of Rh/ ZnO ultrasmall nanoislands

Precise electronic control of metal sites is key to overcoming competitive adsorption in hydroformylation. Herein, we establish a dynamic electronic metal–support interaction in Rh–ZnO/SiO 2 catalyst, where atomically dispersed Rh on reducible ~2 nm ZnO nanoislands enables continuous electronic tuning of Rh. Unlike bulk ZnO, the lattice oxygen in these ultrasmall ZnO islands is more readily removed by H 2 , generating oxygen‐deficient ZnO islands. Notably, the Fermi level reshift is strongly correlated with the oxygen defect concentration as the reduction temperature increases from 100°C to 600°C, continuously driving electron transfer between Rh and ZnO. In styrene hydroformylation, this correlation translates into a volcano‐shaped activity dependence on the reduction temperature of Rh–ZnO/SiO 2 pretreatment. The optimal catalyst (RhZn‐400) outperforms its counterparts by factors of 3.5 and 1.5. Operando DRIFTS and DFT simulations identify the activity apex as a Sabatier optimum, where moderate electron enrichment achieves balanced adsorption of competing intermediates.