Towards highly active heterogeneous catalysts via a sequential noncovalent bonding strategy

Abstract

Here, a novel synthetic route to achieve ceria-based nanocatalysts with high catalytic activity and excellent stability was constructed by utilizing functional groups from surface ligands. The surface of ceria nanorods was functionalized with 3,4-dihydroxyhydrocinnamic acid (3,4-DHCA) to form self-assembled monolayers on their surfaces. Owing to the COO⁻ group on the tail of ligands, the ceria nanorods are negatively charged with good colloidal stability in water. Then, Cu²⁺ was added to coordinate with the COO⁻ group on the tail of ligands to form stable chelating complexes. After calcination, the Cu atoms are firmly anchored onto the surface of ceria nanorods with high dispersibility. Moreover, the Cu²⁺ coordinated ceria nanorods could adsorb PdCl₄²⁻ anions by electrostatic forces onto coordinated copper sites. After calcination, Pd–Cu/CeO₂ nanocatalysts with enhanced CO oxidation catalytic performance were obtained. This coordination strategy is further applied to other metal species such as Fe, Co, and Ni, which provides a great strategy for catalyst preparation.