Design of Pd–Graphene–Au Nanorod Nanocomposite Catalyst for Boosting Suzuki–Miyaura Coupling Reaction by Assistance of Surface Plasmon Resonance

Visible-light boosting chemical reactions by surface plasmon resonance (SPR) have recently received much attention in photocatalysis. Although multiple types of plasmonic catalysts have been developed, the efficient utilization of SPR-induced hot-electrons remains to be a challenging task due to their ultrafast decay. In this study, structure-controlled Pd-graphene-Au nanorod nanocomposite catalysts are fabricated for maximizing hot-electron utilization in SPR-enhanced reactions. The characterization confirmed that highly dispersed Pd clusters were deposited on a homogeneous reduced graphene oxide (rGO) layer-coated Au nanorods. The catalytic activity in the Suzuki–Miyaura coupling reaction was highly enhanced under visible-light irradiation due to the SPR of the Au nanorods, whose performance was superior to that without an rGO layer. Further experimental and calculation study demonstrated that the electro-conductive rGO layer plays a crucial role as an electron mediator for promoting hot-electron transportation from Au to Pd, which resulted in the reaction acceleration

Sequential Catalysis of Defected-Carbon and Solid Catalyst in Li–O₂ Batteries

Lithium–oxygen batteries show great promise as energy storage devices but suffer from high overpotential, which is a major cause of poor cycle stability. To reduce the overpotential, catalysis on a carbon-based cathode is crucial. This work examines the sequential catalysis of a carbon-based cathode containing basal defects and Ru nanoparticles. A new type of carbon cathode is fabricated by dispersing Ru nanoparticles onto a highly mesoporous carbon framework of mainly single-walled curved graphene, which has abundant basal defects but few edge sites. This novel cathode exhibits unique sequential catalysis by forming two distinct morphologies of lithium peroxide in the discharge process. These two morphologies are decomposed at different potentials during charging. A comprehensive analysis, including in situ differential electrochemical mass spectrometry, reveals that the low and high-potential charging plateaus are induced by two different catalytic mechanisms derived from basal defects and Ru nanoparticles, respectively. Interestingly, these two mechanisms do not interfere with each other but act sequentially, reducing the overpotential and thus enhancing the cycle stability

Effects of Carbon Support Nanostructures on the Reactivity of a Ru Nanoparticle Catalyst in a Hydrogen Transfer Reaction

Carbon materials have been extensively studied for several decades as catalytic supports because of their high surface area and porous structures. However, carbon black supports, such as Ketjen black or Vulcan XC-72, have rarely been utilized for organic syntheses, though they have recently been widely studied in electrocatalysts. In this study, we examined Ketjen black with high surface area and high pore volume as a support for Ru nanoparticles (NPs) in the catalytic transfer hydrogenation (CTH) reaction. The performance of the Ru NP catalyst supported on Ketjen black was superior to that on other carbon supports. The catalysts were structurally characterized using X-ray diffraction, X-ray absorption fine structure, transmission electron microscopy, CO chemisorption, and N2 adsorption/desorption measurements. A clear correlation was observed among the micro- and mesopore volume, the adsorption capacity of reactant, and the catalytic activity, and therefore, micro- and mesopores in Ketjen black were found to adsorb the reactant, acetophenone, and thus play a crucial role in achieving high catalytic performance in the CTH reaction