Surface Engineering of Oxide-Supported Catalysts for Renewable Chemistry

Designing oxide-supported noble-metal catalysts that deliver high activity with long operating cycle at low metal loadings remains a central challenge for renewable chemistry. Deactivation by sintering, surface poisoning, and irreversible restructuring often offsets the benefits of atom-efficient formulations, while regeneration protocols can further degrade structure-performance relationships. This thesis advances a surface-chemistry-led approach on commercial Al2O3 that couples (i) bottom-up dispersion improvement via carbonyl surface modification with (ii) post-synthesis interfacial control using liquid-phase atomic layer deposition (L-ALD) alumina overcoats. Together, these strategies minimize precious-metal usage while preserving accessibility of active sites and enabling reversible regeneration. In the first part, transient carbonyl groups were introduced on commercial Al2O3 to form surface complexes that directed the emergence of single atoms and low-nuclearity clusters of Pd and Ru under scalable, ligand-free conditions. Various characterizations: aberration-corrected HAADF-STEM, EXAFS, CO-DRIFTS, and XPS, confirmed the high dispersion and revealed that the electronic/coordination environments of metal species persisted after calcination and reduction. Catalytic tests demonstrated that nuclearity was a decisive lever: highly dispersed Pd exhibited elevated intrinsic activity in low-temperature CO oxidation, whereas highly dispersed Ru promoted selective C-O bond activation in furfuryl-alcohol hydrodeoxygenation. These results established nuclearity-controlled selectivity as a practical handle for reaction design. In the second part, ultrathin alumina overcoats were deposited by L-ALD onto preformed small metal nanoparticles. Under reducing and cycling conditions, the overcoats underwent controlled, non-uniform reconstruction: partial coverage was maintained while metal surfaces were selectively exposed elsewhere. This 'breathable' overcoat architecture suppressed sintering without sacrificing accessible sites, thereby stabilized particle size and preserved activities over repeated regeneration cycles. Time-dependent structure evolution measured by ex-situ and operando probes supported a mobile, reconfigurable overcoat at comparatively mild temperatures. Taken together, carbonyl anchoring (atom-economical dispersion) and L-ALD alumina overcoats (protecting layers) constitute a coherent strategy for engineering oxide-supported catalysts. The concepts are operationally simple, compatible with commercial supports and provide independent, complementary controls to balance stability and accessibility. Overall, this work demonstrates that carefully designed surface chemistry can reconcile atom efficiency with regenerability in noble-metal catalysis. By uniting atom-level dispersion with reconfigurable interfacial overcoats, this thesis delivers practical guidelines and diagnostic tools for building stable, efficient noble-metal catalysts, while