Noble metal

About: Noble metal is a research topic. Over the lifetime, 15113 publications have been published within this topic receiving 337947 citations.

MOF-derived surface modified Ni nanoparticles as an efficient catalyst for the hydrogen evolution reaction

Abstract: Pyrolysis of a Ni based metal organic framework in NH3 yields Ni nanoparticles with surface nitridation together with thin carbon coating layers. The subtle surface modification significantly improves the catalytic performance for the hydrogen evolution reaction (HER). The surface modified Ni nanoparticles show a low overpotential of only 88 mV at a current density of 20 mA cm−2, which is one of the most efficient HER catalysts based on metallic Ni reported so far. The results suggest that controlled pyrolysis of MOFs is an effective method to prepare highly efficient noble metal free HER catalysts.

Photochemical Synthesis of Noble Metal (Ag, Pd, Au, Pt) on Graphene/ZnO Multihybrid Nanoarchitectures as Electrocatalysis for H2O2 Reduction

Abstract: For the first time, a series of noble metal (Ag, Au, Pd, and Pt) nanoparticles (NPs) based on new functional graphene were successfully achieved via UV-assisted photocatalytic reduction by ZnO nanorods. The whole preparation strategy for constructing noble metal deposited graphene sheets/ZnO (GS/ZnO) was elucidated in detail in this work. First, graphene oxide based two-dimensional carbon nanostructures served as a support to disperse ZnO nanorods through a hydrothermal route. The ZnO nanorods were self-assembled onto the surface of graphene sheets, forming GS/ZnO nanocomposite, and the graphene oxide was reduced, yielding reduced graphene sheets in this synthetic procedure. Second, the GS/ZnO films were further employed as supporting materials for the dispersion of metal nanoparticles. Photogenerated electrons from UV-irradiated ZnO were transported across GS to stepwise and respectively reduce v μL metal ions (Ag+, Pd2+, AuCl4–, PtCl62-, 20 mg/mL) into metal (Ag, Pd, Au, Pt) NPs at a location distinct f...

A CuO-CeO2 mixed-oxide catalyst for CO clean-up by selective oxidation in hydrogen-rich mixtures

Abstract: A CuO-CeO2 mixed-oxide catalyst was shown experimentally to be highly active and selective for the oxidation of CO in hydrogen-rich mixtures, and an attractive alternative to the noble metal catalysts presently used for CO clean-up in hydrogen mixtures for proton-exchange membrane fuel cells (PEMFC) Although the presence of H2O and CO2 in the feed decreased the activity and increased the reaction temperature considerably to achieve a given CO conversion with a reactor, the selectivity profile with respect to the conversion remained virtually the same The effect of H2O and CO2 on the reaction was found to increase the required energy for reduction of the active copper species in the redox cycles undergone during the reaction The catalyst showed a slow, reversible deactivation, but the activity was restored on heating the catalyst at 300 °C, even under an inert flow At space velocities above 42 g h m-3, the catalyst reduced the CO content to less than 10 ppm in the temperature range 166-176 °C for a feed of 1% CO, 1% O2, 50% H2, 20% H2O, 135% CO2 and balance He Hence, with this catalyst it is feasible to clean up the CO in a single-stage reactor with relatively small excess oxygen, which is in contrast to the typical multistage reactor systems using noble metal catalysts

Studies of metal–support interactions with “real” and “inverted” model systems: reactions of CO and small hydrocarbons with hydrogen on noble metals in contact with oxides

Abstract: Two types of model catalysts are compared: thin film catalysts consisting of polyhedral noble metal nanocrystals (Rh and Pt) supported by reducible and non‐reducible oxides, and their inverted pendants, submonolayers of titania and vanadia deposited under UHV conditions on the respective metal surfaces (Pd and Rh(111) and Rh (polycrystalline)). The structure and composition of the inverse catalysts were examined in situ by LEED and AES and the nanoparticles were characterized by HRTEM. The activity of thin film and inverse catalysts was studied in a series of reactions, such as the ring opening of methylcyclopentane and methylcyclobutane, the dissociation of CO and the CO methanation. Reaction conditions comprise atmospheric pressure but also molecular beam experiments. The reaction rates are related to the oxidation state of the supporting oxide, to the free metal surface area and to the number of sites at the interface between metal and support.