Neighboring Rh nanoclusters promote the activity and stability of Rh single-atom catalyst for the hydroformylation of sterically hindered diisobutylene

Abstract Developing efficient and leaching-resistant heterogeneous Rh catalysts for the hydroformylation of sterically hindered olefins remains a formidable challenge. Herein, we report a ligand-free heterogeneous Rh catalyst (Rh/N-AC-T), featuring a proximal dual-active-site architecture, in which Rh single atoms and nanoclusters are co-anchored on nitrogen-doped carbon (Rh/N-AC-T). The optimized Rh/N-AC-650 catalyst exhibits outstanding catalytic performance in the hydroformylation of diisobutylene (DIB), delivering high catalytic activity, excellent structural stability, and negligible Rh leaching during continuous-flow operation for over 200 h. Comprehensive spectroscopic characterizations combined with density functional theory calculations suggest that the intimate coupling between adjacent Rh single atoms and nanoclusters modulates the Rh electronic structure and the adsorption balance of H2, DIB, and CO. The dual-site interface facilitates H2 activation and lower the relative energy barrier for the rate-determining CO-insertion step, accounting for the enhanced hydroformylation performance. Meanwhile, pyridinic N species within the carbon framework benefit for the stronger interactions between Rh species and support, thereby helping suppress Rh aggregation and leaching under harsh reaction conditions. This work establishes proximal Rh single atom-nanocluster dual sites as an effective design strategy for constructing high-performance, ligand-free heterogeneous catalysts for challenging carbonylation reactions.