Dual Optimization Approach to Bimetallic Nanoparticle Catalysis: Impact of M₁/M₂ Ratio and Supporting Polymer Structure on Reactivity

Abstract

A dual optimization approach to nanoparticle catalysis is reported in which both the composition of a bimetallic nanoparticle and the electronic properties of the supporting polystyrene-based polymer can be varied to optimize reactivity and chemoselectivity in nitroarene reductions. Ruthenium–cobalt nanoparticles supported on polystyrene are shown to catalyze nitroarene reductions at room temperature with exceptional activity, as compared with monometallic ruthenium catalysts. Both the identity of the second metal and the M1/M2 ratio show a profound effect on the chemoselectivity of nitroarene reductions. These polymer-supported bimetallic catalysts are shown to react with nearly complete chemoselectivity for nitro group reduction over a variety of easily reducible functional groups. The electronic properties of the supporting polymer also have a significant impact on catalysis, in which electron-deficient polystyrenes enable 100% conversion to the aniline product in just 20 min at room temperature. Polymer effects are also shown to influence the mechanism of the reduction reaction, in addition to accelerating the rate, confirming the impact of the polymer structure on catalytic efficiency. These catalysts are easily prepared in a single step from commercial materials and can be readily recycled without loss of activity.

Untangling the Role of the Capping Agent in Nanocatalysis: Recent Advances and Perspectives

“…The main limitation of this reaction is the very low selectivity to alkenes, due to the fast over-hydrogenation of Electro-donation from ligands to metal does not always lead to a beneficial effect. Recently, Michaelis et al [58] investigated the possibility to tailor the catalytic performances of bimetallic RuCo NPs, by properly tuning the electronic properties and the donor ability of the protecting polymer. The introduction of electron-donating substituents on polystyrene chains leads to a reduced electron density and a weaker interaction between metal nanoparticle surface and arene π-electrons, which allows polystyrene to dissociate from metal surface.…”

“…Consequently, the metal surface accessibility and the catalyst activity in nitroarenes reduction are enhanced. Conversely, the introduction of electron-withdrawing substituent transforms polystyrene into an electron-rich system that strongly interacts with the metal surface and further acts as a poisoner [58].…”

Molecular tunability of surface-functionalized metal nanocrystals for selective electrochemical CO2 reduction

“…In contrast, pristine metallic surfaces are conventionally preferred for studies in heterogeneous catalysis. Nevertheless, the promoting effects of tailor-made ligands on heterogeneous catalysts are boldly emerging in various reactions, ranging from catalytic organic transformations [1][2][3][4][5] to photocatalysis [6][7][8] and electrocatalysis, including the oxygen-reduction reaction (ORR) 9 and the hydrogen-evolution reaction (HER). [10][11][12] The electrochemical reduction of carbon dioxide (CO 2 RR) holds enormous potential to meet modern-day challenges in energy storage thanks to its ability to convert CO 2 into energydense and transportable hydrocarbons and alcohols.…”

Facile Fabrication of Ordered Component-Tunable Heterobimetallic Self-Assembly Nanosheet for Catalyzing “Click” Reaction

“…It has been based on the hypothesis that interactions between the metals on the surface and the electrons of the aromatic rings having nitrogen atom in the ligand facilitate the formation of the controlled nanocatalyst and stabilize the resulting nanoactive species toward oxidation. 51 At the same time, if the groups complexed with different metals are too far apart, they cannot cooperate; however, if they are too close, they may interact in an intramolecular fashion and thus prevent the association of the substrate. This strategy has the potential to simplify catalyst optimization in heterogeneous catalysis, similar to what is accomplished by a modified ligand in homogeneous transition-metal catalysis.…”