Donor/Acceptor Concepts for Developing Efficient Suzuki Cross-Coupling Catalysts Using Graphene-Supported Ni, Cu, Fe, Pd, and Bimetallic Pd/Ni Clusters

Abstract

First-principles theoretical studies on the electronic properties and activation energies for the three steps of the Suzuki cross-coupling reaction have been performed on 3d transition-metal clusters and Pd/Ni bimetallic clusters supported on defected graphene. The ability of the clusters to effectively donate and accept charge is found to be critical to the activity of the catalysts, and graphene further enhances this ability. Nickel acts as the best replacement for palladium in cross-coupling catalysts for the oxidation steps but is not a good replacement in the transmetallation and reductive elimination steps which require the cluster to serve as a charge acceptor. Reducing the size of the cluster from Ni13 to Ni4 enhances the activity because of the cluster being more positively charged. Bimetallic Pd/Ni clusters were found to offer even lower activation energies for all three steps of the Suzuki reaction because of charge donation from the Ni atoms to the Pd atoms making the bimetallic cluster a highly active co-catalyst. This study reveals that the donor–acceptor concepts that explain the enhanced activity of Pd clusters on defected graphene can also be applied to explain lowered activation energies in bimetallic clusters acting as co-catalysts.

Adsorption Energy Shifts for Oxygen and Hydroxyl on 4-atom Metal-Decorated Graphene Catalysts Via Solvation, pH, and Substrate Dopants: Effects on ORR Activity

“…At the likely pH and solvent stabilization of real working fuel cells, not all of these systems may be thermodynamically or kinetically stable; however, our results provide context for the limits upon which systems may perform and the theoretical overpotentials which they may achieve. Specifically, metallic NP such as Cu 3 Ni are not likely to be stable on MDG at pH values of 0 or 1; working ORR MDG Cu 3 Ni would likely need to be operated at weaker pH to prevent dissolution of durability issues, or larger catalyst NP would potentially overcome this issue [35][36][37][38][39][40]. (We note larger catalyst NP to be studied are beyond the scope of the work in this manuscript).…”

Carbon‐Based Material‐Supported Palladium Nanocatalysts in Coupling Reactions: Discussion on their Stability and Heterogeneity

“…The leaching of Ni and Pd may change the morphology of the 3D composites and reduce their catalytic activity, but requires further catalyst recycling experiments and morphological characterization. Nonetheless, it is known that the high activity of graphene‐ and CNT‐supported catalysts is derived from the conductive properties of the sp 2 ‐hybridized carbon …”

Graphitic Carbon Nitride (g‐C3N4) Supported Palladium Species: An Efficient Heterogeneous Photocatalyst Surpassing Homogeneous Thermal Heating Systems for Suzuki Coupling

“…On the other hand, although Pd nanoparticles capped with relatively large molecular strand, for example oleic acid and polyvinylpyrrolidone, are stable in organic solvent, the strong steric hinderance of surfactants greatly reduces the catalytic activity of Pd nanoparticles. The other type of heterogeneous catalysts is Pd atom, clusters, or nanoparticles anchored on supports . The supported Pd catalysts can exist stably without any surfactants and therefore effectively circumvent the reduction of catalytic activity induced by the aggregation and steric hinderance of surfactants …”

“…Therefore, many efforts have been devoted to developing heterogeneous catalysts for Suzuki coupling reactions. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] One typical type of heterogeneous catalysts for Suzuki coupling reactions is pure Pd nanoparticles. [8][9][10][11][12][13] Since aryl halide is not soluble in water, the solvents widely used for Suzuki coupling reaction are organic solvent.…”

“…[5][6][7]15,20] The supported Pd catalysts can exist stably without any surfactants and therefore effectively circumvent the reduction of catalytic activity induced by the aggregation and steric hinderance of surfactants. [5][6][7]15,20] Most of Suzuki coupling reactions takes place at thermal heating conditions, which consumes a relatively large amount of energy. To realize green Suzuki coupling reactions, Pd are integrated with solar active materials which absorb light to provide energy for reaction.…”