Engineering Surface Ligands of Noble Metal Nanocatalysts in Tuning the Product Selectivity

Nanosized noble metal catalysts supported on high-surface-area support are of great importance for numerous industrial chemical processes to mediate reaction pathways in heterogeneous catalysis. Control of surface area and surface energy of nanocatalysts is a key to achieving high activity and selectivity for desired products. In the past decade, new synthetic methodologies for noble metal nanocatalysts with well-defined nanostructures have been developed. Wet-chemical preparation of noble metal nanocatalysts usually involves the utilization of specific surfactants that can bind the surface of nanocatalysts as ligands to control the nanostructures and prevent the coalescence of nanocatalysts. Surface ligands that form a densely packed self-assembled monolayer offer a facile solution to tune the surface energy of nanocatalysts, and, therefore, the selectivity of products. In this minireview, we highlight the recent advances in understanding the role of surface ligands in control over the product selectivity in a multi-product reaction using noble metal nanocatalysts. The review is outlined according to the three possible roles of surface ligands, including steric effect, orientation effect and surface charge state, in varying the adsorption/binding of reactants/transition states.