The activities of different types of PtRu catalysts for methanol oxidation are compared. Materials used
were: UHV-cleaned PtRu alloys, UHV-evaporated Ru onto Pt(111) as well as adsorbed Ru on Pt(111)
prepared with and without additional reduction by hydrogen. Differences in the catalytic activity are
observed to depend on the preparation procedure of the catalysts. The dependence of the respective catalytic
activities upon the surface composition is reported. UHV−STM data for Pt(111)/Ru show the formation
of two- and three-dimensional structures depending on surface coverage. A molecular insight on the
electrochemical reaction is given via in situ infrared spectroscopy. Analysis of the data indicates that the
most probable rate-determining step is the reaction of adsorbed CO with Ru oxide.
Opportunities and challenges in tailoring layered double hydroxides and constructing them into superaerophobic nanoarray electrodes for an efficient oxygen evolution reaction
The electrochemical uptake of oxygen on a Ru(0001) electrode was investigated by electron diffraction, Auger
spectroscopy, and cyclic voltammetry. An ordered (2 × 2)-O overlayer forms at a potential close to the
hydrogen region. At +0.42 and +1.12 V vs Ag/AgCl, a (3 × 1) phase and a (1 × 1)-O phase, respectively,
emerge. When the Ru electrode potential is maintained at +1.12 V for 2 min, RuO2 grows epitaxially with
its (100) plane parallel to the Ru(0001) surface. In contrast to the RuO2 domains, the non-oxidized regions
of the Ru electrode surface are flat. If, however, the electrode potential is increased to +1.98 V for 2 min,
the remaining non-oxidized Ru area also becomes rough. These findings are compared with O overlayers and
oxides on the Ru(0001) and Ru(101̄0) surfaces created by exposure to gaseous O2 under UHV conditions. On
the other hand, gas-phase oxidation of the Ru(101̄0) surface leads to the formation of RuO2 with a (100)
orientation. It is concluded that the difference in surface energy between RuO2(110) and RuO2(100) is quite
small. RuO2 again grows epitaxially on Ru(0001), but with the (110) face oriented parallel to the Ru(0001)
surface. The electrochemical oxidation of the Ru(0001) electrode surface proceeds via a 3-dimensional growth
mechanism with a mean cluster size of 1.6 nm, whereas under UHV conditions, a 2-dimensional oxide film
(1−2 nm thick) is epitaxially formed with an average domain size of 20 μm.
A comparative study of CO electrooxidation on different catalysts using in situ FTIR spectroscopy is presented.
As electrode materials, polycrystalline Pt and Ru and a PtRu (50:50) alloy are used. The latter is one of the
well-known active alloys for CO oxidation. The potential dependence of the band frequencies for the CO
stretch indicates the formation of relatively compact islands at pure Pt and Ru, and a loose adlayer structure
at the alloy. This loose structure has a positive effect on the rate of oxidative desorption. CO submonolayer
coverages are obtained by integrating the absorption bands for CO2 produced upon oxidation of adsorbed
CO. The band intensities measured at Pt, Ru, and PtRu indicate an influence of the substrate on the absorption
coefficient of the CO stretch. It is shown that for a correct description of the catalyst properties toward CO
electrooxidation, it must be distinguished between bulk and adsorbed CO. In contrast to the statement of
most of the recent papers that a PtRu alloy (50:50) is the material with the highest activity for CO oxidation,
it is demonstrated and rationalized in the present paper that for bulk CO oxidation pure Ru is the best catalyst.
We developed a novel methodology for the general synthesis of non-precious transition metal–nitrogen–carbon electrocatalysts based on formamide condensation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.