Author
Pavel Janda
Other affiliations: Leibniz Association, Charles University in Prague, University of York
Bio: Pavel Janda is an academic researcher from Academy of Sciences of the Czech Republic. The author has contributed to research in topics: Raman spectroscopy & X-ray photoelectron spectroscopy. The author has an hindex of 18, co-authored 41 publications receiving 1121 citations. Previous affiliations of Pavel Janda include Leibniz Association & Charles University in Prague.
Papers
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TL;DR: In this article, the tetra-aminophthalocyane to, cobalt(II) species adsorbed onto graphite electrodes are active in electrocatalytic oxygen reduction.
Abstract: The monomeric and polymeric tetra-aminophthalocyane to, cobalt(II) species adsorbed onto graphite electrodes are active in electrocatalytic oxygen reduction. While the monomeric species is unstable, the polymerized species is an effective and stable reduction catalyst over a wide pH range. Both the two-electron reduction of oxygen to hydrogen peroxide and the four-electron reduction of oxygen to water are characterized by cyclic voltammetry, rotating disc and rotating ring-disc studies with appropriate theoretical analysis. Some mechanistic information is obtained. This is the first cobalt phthalocyanine species to provide a four-electron reduction pathway which exists over a wide pH range and is stable. The stability is associated with the polymerization since the monomeric species is not stable.
107 citations
TL;DR: It is shown that the bottom layer of the bilayer graphene is significantly doped from the substrate, while the top layer does not exhibit a signature of the doping from the environment.
Abstract: Bilayer graphene was prepared by the subsequent deposition of a 13C single-layer graphene and a 12C single-layer graphene on top of a SiO2/Si substrate. The bilayer graphene thus prepared was studied using Raman spectroscopy and in situ Raman spectroelectrochemistry. The Raman frequencies of the 13C graphene bands are significantly shifted with respect to those of 12C graphene, which allows us to investigate the single layer components of bilayer graphene individually. It is shown that the bottom layer of the bilayer graphene is significantly doped from the substrate, while the top layer does not exhibit a signature of the doping from the environment. The electrochemical doping has the same effect on the charge carrier concentration at the top and the bottom layer despite the top layer being the only layer in contact with the electrolyte. This is here demonstrated by essentially the same frequency shifts of the G and G′ bands as a function of the electrode potential for both the top and bottom layers. Nev...
103 citations
TL;DR: In this article, a modified HOPG electrode has been further coated with Nafion or Tosflex ion exchange membranes and used in the determination of concentration of sulfide ion and 2-mercaptoethanol by direct potentiometry.
Abstract: Electroreduction of N,N',N'',N'''-tetramethylmetra-3,4-pyridinoprophyrazinocobalt(II) in aqueous buffer phosphate solution leads to the deposition of an insoluble tetrapyridinoporphyrazinocobalt(I) phthalocyanine film on the highly oriented pyrolytic graphite (HOPG) electrode. This modified HOPG electrode has been further coated with Nafion or Tosflex ion-exchange membranes and used in the determination of concentration of sulfide ion and 2-mercaptoethanol by direct potentiometry
94 citations
TL;DR: In this paper, the tetraaminophthalocyanatocobalt (II) was electropolymerized onto an electrode surface and used for the quantitative estimation of sulfide ion and 2-mercaptoethanol over a wide pH range.
Abstract: The complex tetraaminophthalocyanatocobalt(II), electropolymerized onto an electrode surface, serves as an excellent sensor for the quantitative estimation of sulfide ion and 2-mercaptoethanol over a wide pH range. Appropriate electrochemical and analytical data are presented
91 citations
TL;DR: In this article, electrochemical reduction and oxidation of anatase allowed the reversible alteration of the electron density and this influenced its performance as a photoelectrode, the level of which was indicated by variations in the course of reactions taking place on the anatase/electrolyte interface.
91 citations
Cited by
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TL;DR: Biesinger et al. as mentioned in this paper proposed a more consistent and effective approach to curve fitting based on a combination of standard spectra from quality reference samples, a survey of appropriate literature databases and/or a compilation of literature references and specific literature references where fitting procedures are available.
7,498 citations
TL;DR: In this article, an overview and review on self-organized TiO2 nanotube layers and other transition metal oxide tubular structures grown by controlled anodic oxidation of a metal substrate is given.
Abstract: The present paper gives an overview and review on self-organized TiO2 nanotube layers and other transition metal oxide tubular structures grown by controlled anodic oxidation of a metal substrate We describe mechanistic aspects of the tube growth and discuss the electrochemical conditions that need to be fulfilled in order to synthesize these layers Key properties of these highly ordered, high aspect ratio tubular layers are discussed In the past few years, a wide range of functional applications of the layers have been explored ranging from photocatalysis, solar energy conversion, electrochromic effects over using the material as a template or catalyst support to applications in the biomedical field A comprehensive view on state of the art is provided
1,242 citations
01 Mar 2001
TL;DR: In this paper, a unique chirality assignment was made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t).
Abstract: We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an (n,m) individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode frequency omega(RBM) and using the theory of resonant transitions. A unique chirality assignment can be made for both metallic and semiconducting nanotubes of diameter d(t), using the parameters gamma(0) = 2.9 eV and omega(RBM) = 248/d(t). For example, the strong RBM intensity observed at 156 cm(-1) for 785 nm laser excitation is assigned to the (13,10) metallic chiral nanotube on a Si/SiO2 surface.
1,180 citations
921 citations
TL;DR: Focusing on two application areas, namely communications and photovoltaics, the state of the art in each field is assessed and the challenges that need to be overcome are highlighted to make silicon a truly high-performing photonic material.
Abstract: Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanoscale engineering of the electronic and photonic properties, are starting to change the picture, and some silicon nanostructures now approach or even exceed the performance of equivalent direct-bandgap materials. Focusing on two application areas, namely communications and photovoltaics, we review recent progress in silicon nanocrystals, nanowires and photonic crystals as key examples of functional nanostructures. We assess the state of the art in each field and highlight the challenges that need to be overcome to make silicon a truly high-performing photonic material.
798 citations