Peter Bogdanoff

Helmholtz-Zentrum Berlin | HZB · Institute for Solar Fuels

Cyclic voltammetry measurements are carried out in neutral phosphate buffered electrolyte using n-type Ga-polar GaN thin film photoelectrodes with and without cobalt phosphate (Co-Pi) modification. Without Co-Pi, the variation of the photocurrent with the bias potential exhibits a two-step behavior, and under chopped illumination spikes occur at lo...

α-Mn2O3 is of interest as a low-cost and environmentally benign electrocatalyst for the Oxygen Evolution Reaction (OER) in the process of water splitting. Mechanically stable α-Mn2O3 electrodes are prepared by annealing of galvanostatically deposited MnOOHx layers on F:SnO2-coated glass. The overpotential η to achieve a current density of j = 10 mA...

GaN nanowires (NWs) doped with Mg as a p-type impurity were grown on Si(111) substrates by plasma-assisted molecular beam epitaxy. In a systematic series of experiments, the amount of Mg supplied during NW growth was varied. The incorporation of Mg into the NWs was confirmed by the observation of donor-acceptor pairs and acceptor-bound excitons in...

The photoelectrochemical properties of (In,Ga)N nanowire photoanodes are investigated using H2O2 as a hole scavenger in order to prevent photocorrosion. Under simulated solar illumination, In0.16Ga0.84N nanowires grown by plasma-assisted molecular beam epitaxy show a high photocurrent of 2.7 mA/cm2 at 1.2 V vs. reversible hydrogen electrode (RHE)....

Intermediate band semiconductors have raised interest as materials to both enhance photovoltaics’ efficiency and promote photocatalytic activity driven by visible light. The present work shows the synthesis of In2S3 doped with four different ratios of V using ILGAR technique. This nebulize-spray based technique allows the deposition of In2(V)S3 thi...

CuBi2O4 is a multinary p-type semiconductor that has recently been identified as a promising photocathode material for photoelectrochemical (PEC) water splitting. It has an optimal bandgap energy (~ 1.8 eV) and an exceptionally positive photocurrent onset potential (> 1 V vs. RHE) making it an ideal candidate for the top absorber in a dual absorber...

Architectures with various degrees of integration are investigated for water splitting devices using the energy of light for fuel production. The many approaches presented in literature for such ‘photo driven catalytic (PDC) devices’ are reviewed and discussed in perspective of their scalability to large area. Then, back-of-the-envelope type techno...

An integrated water-splitting device based on a triple-junction silicon-based solar cell (a-Si:H/a-Si:H/μc-Si:H; a-Si=amorphous silicon, μc-Si=microcrystalline) in superstrate configuration modified with catalysts at the back and front contacts is described. In this configuration, the solar cell is illuminated by the glass substrate, while the back...

Today, most metal and nitrogen doped carbon catalysts for ORR reveal a rather heterogeneous composition. This can be reasoned by a non-optimized precursor composition and different steps in the preparation process to get the required active material. The significant presence of inorganic metal species interfere the assignment of descriptors related...

In this study, a promising alternative method for addressing grain boundary issues in hematite (α-Fe2O3)-based photoanodes is presented. The porous α-Fe2O3 films are prepared by dip coating a polymerizable precursor onto fluorine-doped tin oxide (FTO) substrates. The photoelectrochemical (PEC) performance of α-Fe2O3 photoanodes is characterized and...

A typical procedure based on sol-gel aggregation for the fabrication of mesoporous WO3 photoanodes was modified and used produce modified tungsten oxide films by utilizing the tungstic acid sol admixed with Keggin-type borotungstic acid (H5BW12O40) or the borotungstic acid-stabilized hematite (Fe2O3). Physicochemical properties (structure, morpholo...

Novel thin film composite photocathodes based on device-grade Cu(In,Ga)Se2 chalcopyrite thin film absorbers and transparent conductive oxide Pt-implemented TiO2 layers on top are presented for an efficient and stable solar-driven hydrogen evolution. Thin films of phase-pure anatase TiO2 are implemented with varying Pt-concentrations in order to opt...

Ultra-thin α-Fe2O3 (hematite) films have been deposited by radio frequency (RF) sputtering technique and photoelectrochemically investigated towards their ability to oxidize water. By varying the deposition power and time as well as the sputter gas flow (argon), the microstructure and morphology of the film were optimized. It was found that the inc...

Water oxidation by amorphous oxides is of high interest in artificial photosynthesis and other routes towards non-fossil fuels, but the mode of catalysis in these materials is insufficiently understood. We tracked mechanistically relevant oxidation-state and structural changes of an amorphous Co-based catalyst film by in-situ experiments combining...

The applicability of analyzing by MoBbauer spectroscopy the structural changes of Fe-N-C catalysts that have been tested at the cathode of membrane electrode assemblies in proton exchange membrane (PEM) fuel cells is demonstrated. The MoBbauer characterization of powders of the same catalysts was recently described in our previous publication. A po...

We report the deposition of ultra-thin a-Fe2O3 (hematite) films on fluorine-doped tin oxide (FTO) substrates using radio frequency (RF) sputtering, and the investigation of their photoelectrochemical (PEC) performance towards water oxidation. By varying the deposition pressure and time, the film microstructure and morphology could be optimized. The...

In the effort to develop an efficient and cost effective photo-electrochemical device for water splitting driven by sunlight only, transition metal oxides are promising candidates to catalyze the oxygen evolution reaction (OER) at the anode. We used X-ray photoelectron spectroscopy (XPS) to characterize very active manganese and cobalt oxide thin f...

The compound semiconductor RuS2, known as mineral laurite, has been investigated as a potential (photo)electrochemically active anode material for the oxygen evolution in the process of (photo)electrolytic water splitting. The contribution describes for the first time the preparation of RuS2 thin films deposited on (100)- and (111)-oriented FeS2 (p...

Hematite is a promising anode material for photoelectrochemical (PEC) water splitting due to its suitable chem- ical and physical properties. Although considerable effort has been devoted, the detailed mechanisms are still unclear. In our work, nanostructured hematite films were made by low cost dip coating procedure and its pho- toelectrochemical...

Different manganese oxide phases were prepared as thin films to elucidate their structure–function relationship with respect to oxygen evolution in the process of water splitting. For this purpose, amorphous MnOx films anodically deposited on F:SnO2/glass and annealed at different temperatures (to improve film adherence and crystallinity) were test...

Cold gas spraying (CGS) is presented as an innovative approach to deposit semiconductor particles onto substrates in order to form photoelectrodes for electrochemical applications. Thin layers of TiO2 (P25-20 by Evonik Industries) are deposited onto titanium substrates (TiO2-CGS films) at different temperatures of the gas carrier within the CGS pro...

In this work Fe–N–C catalysts were prepared by the oxalate-supported pyrolysis of FeTMPPCl or H2TMPP either in the presence or absence of sulfur. The well-known enhancing effect of sulfur-addition on the oxygen reduction activity was confirmed for these porphyrin precursors. The pyrolysis process was monitored in situ by high-temperature X-ray diff...

Solar radiation can be used as a nearly inexhaustible energy source to convert light into chemical energy. In this way fossil fuels can be replaced and a sustainable society established in the future. One promising concept is the production of hydrogen by light powered water electrolysis. In order to provide the required high photo-voltage suitable...

Hydrogen generated by conversion of sunlight into chemical energy is considered as a fuel of the future replacing fossil carbon and hydrocarbons. A sustainable and environmentally acceptable way to produce H 2 is by the photoelectrolysis of water, i.e. the conversion of solar into chemical energy by water splitting. For this purpose we modified a t...

This contribution shows the potential of cold gas spraying for the production of photoelectrodes employing photoelectrocatalysts for the water oxidation reaction. Conventional methods of coating usually employ sol-gel methods and calcination to obtain a good binding of the coating to the substrate. In cold gas spraying, particles are accelerated to...

We investigated the photoelectrochemical properties of both n- and p-type (In,Ga)N nanowires (NWs) for water splitting by in-situ electrochemical mass spectroscopy (EMS). All NWs were prepared by plasma-assisted molecular beam epitaxy. Under illumination, the n-(In,Ga)N NWs exhibited an anodic photocurrent, however, no O2 but only N2 evolution was...

According to the present invention, the catalyst performance of a chelate catalyst comprising a complex of a macrocyclic compound such as a porphyrin derivative is improved. Also, the following method is provided: a method for preparing a fuel cell electrode catalyst comprising a nitrogen-containing metal complex in which a metallic element is coor...

alpha-Fe2O3 (hematite) photoanodes for the oxygen evolution reaction (OER) were prepared by a cost-efficient sol-gel procedure. We show that annealing and plasma post-treatments improve significantly the photoelectrochemical properties for the OER. Annealing steps lead to a reorganization of the crystal structure and thereby to a pronounced shift o...

We report for the first time the demonstration of high intensity sonication treatment as a simple and effective way to fundamentally improve the performance of nanoparticles for photoelectrochemical (PEC) water splitting. The capability of making highly photoactive nanoparticles by high intensity sonication is highly appreciated to open up new oppo...

Thin layers of ruthenium sulfide (RuS2 ± x, laurite) were deposited on a heated substrate by reactive magnetron sputtering using a metallic ruthenium target and H2S as reactive gas. The balanced magnetron plasmas were excited by a direct-current (DC) or a radio-frequency (RF, 27 MHz) power supply, respectively. To comprehensively study the influenc...

More efficient energy conversion systems may help to reduce the use of fossil fuels and the emission of greenhouse gases. Polymer Electrolyte Membrane Fuel Cells are such devices which are of particular interest for automotive applications. Unfortunately, cost issues are still limiting the application of this technology in a highly competitive mark...

α-Fe(2)O(3) (hematite) photoanodes for the oxygen evolution reaction (OER) were prepared by a cost-efficient sol-gel procedure. Due to low active photoelectrochemical properties observed, it is assumed that the sol-gel procedure leads to hematite films with defects and surface states on which generated charge carriers are recombined or immobilized...

Crystalline RuS(2) layers were prepared on titanium sheets by reactive magnetron sputtering using a metallic ruthenium target and a H(2)S-Ar mixture as process gas. The ability of these layers for the electrooxidation of water (OER) was investigated by differential electrochemical mass spectrometry (DEMS) in 0.5 M H(2)SO(4) electrolyte. It was obse...

This paper summarizes a XANES, XPS, XRD, and Mossbauer study of an oxygen reduction reaction (ORR) catalyst obtained via a heat treatment of polyaniline, iron, and carbon black. The catalyst was characterized at several critical synthesis stages and following heat treatment at various temperatures. The effect of sulfur during the synthesis was also...

Fe-based catalytic sites for the reduction of oxygen in acidic medium have been identified by (57)Fe Mössbauer spectroscopy of Fe/N/C catalysts containing 0.03 to 1.55 wt% Fe, which were prepared by impregnation of iron acetate on carbon black followed by heat-treatment in NH(3) at 950 °C. Four different Fe-species were detected at all iron concent...

Based on the oxygen evolving μ-oxido-Mn4Ca cluster unit in photosynthesis II, Ca2Mn3O8 films prepared by dip-coating and screen-printing were tested as oxygen evolving catalysts. Structural analysis confirmed that smooth 100 nm films can be grown from a Ca2MnO4 sol–gel solution showing a high orientation in (1 0 0) direction when deposited on F:SnO...

The development of novel oxides, nanocomposites and architectures is in demand for the direct conversion of solar energy into other forms of energy, such as chemical and electrical energy. Especially, those oxides and devices, which can be used for photolysis of water (hydrogen and oxygen evolution) and for water purification, are of interest. So f...

Titanium dioxide (rutile) is known as n-type semiconductor. Recent studies show that prolonged oxidation of pure n-type TiO2 may lead to its conversion into a p-type semiconductor. It has been documented that the conversion is associated with the formation of titanium vacancies. The present work derives the defect disorder model of TiO2, which expl...

Nanostructured hematite films prepared by a sol-gel procedure were evaluated for the photo-induced oxygen evolution reaction (OER). Surface treatments such as plasma and post-annealing at 500 degrees C in oxygen gas flow were used in order to condition the electrode surface. Electrochemical measurements of the plasma treated samples revealed that t...

The high cost of proton-exchange-membrane fuel cells would be considerably reduced if platinumbased catalysts were replaced by iron-based substitutes, which have recently demonstrated comparable activity for oxygen reduction, but whose cause of activity decay in acidic medium has been elusive. Here, we reveal that the activity of Fe/N/C-catalysts p...

For the first time, the effect on structure and composition by a second heat treatment in ammonia was studied in detail for Fe–N–C catalysts prepared by oxalate-supported pyrolysis of chloroirontetrametoxyphenylporphyrin (Fe(TMPP)Cl). The oxygen reduction reaction (ORR) activity was determined by rotating ring-disk electrode (RRDE) measurements in...

In former work we had demonstrated that single crystals of the compound semiconductor RuS 2 (laurite) show light-assisted electro-oxidation of water in acidic electrolytes. The material is distinguished by an indirect band gap of 1.36eV and a direct transition at 2.2eV. Since the preparation of RuS 2 single crystals via high temperature growth tech...

Presently our institute pursues the aim to realize a monolithic structure to split water from sunlight by immerging a membrane in an electrolyte consisting of photo-electrocatalytic electrode surfaces to evolve hydrogen and oxygen from water as demonstrated for the first time by Khaselev and Turner in 1998 [1]. For this type of device alternative p...

We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium part...

RuS2 thin films for the oxygen evolution reaction prepared by reactive magnetron sputtering.

Presently our institute pursues the aim to realize a monolithic structure to split water from sunlight by immerging a membrane in an electrolyte consisting of photo-electrocatalytic electrode surfaces to evolve hydrogen and oxygen from water as demonstrated for the first time by Khaselev and Turner in 1998 [1]. For this type of device alternative p...

Sputtered ruthenium disulphide thin layers for the oxygen evolution reaction.

Platinum electrocatalysts for the oxygen reduction reaction have been prepared by impregnation of platinum acetylacetonate on pristine and NH3 treated Black Pearls. The subsequent heat treatment leads to electrochemical active platinum particles in nm-scale (2 - 3 nm). By electrochemical measurements (CV and RDE), the platinum surface properties an...

FeTMPPCl impregnated on a carbon black was heat treated to different temperatures. The obtained catalysts were characterized before and after acid leaching by structural and chemical analyses. On the basis of the structural characterization it was concluded that those FeN4 centres in which iron is mesomerically bonded to four nitrogen atoms, are ca...

A structural model of selenium-modified ruthenium nanoparticles was derived from anomalous small-angle X-ray scattering (ASAXS) and small-angle neutron scattering (SANS) experiments and further approved and supported by TEM, XRD, and extended X-ray adsorption fine-structure (EXAFS) analysis. Carbon-supported ruthenium nanoparticles modified with se...

Presently our institute pursues the aim to realize a monolithic structure to split water from sunlight by immerging a membrane in an electrolyte consisting of photoelectrocatalytic electrode surfaces to evolve hydro-gen and oxygen from water as demonstrated for the first time by Khaselev and Turner in 1998 [1]. For this type of device alternative p...

Kurzfassung Zur Optimierung moderner Katalysatoren für Brennstoffzellen werden diese elektronen-tomografisch charakterisiert. Die Elektronentomografie ermöglicht einzigartige Einblicke in die Nanometer-Strukturen der metallischen Katalysatorpartikel, die auf einem elektrisch leitenden, inerten Kohlenstoffträger abgeschieden werden. Die dreidimensio...

Low temperature plasma (LTP) treatment of cobalt‐tetramethoxyphenylporphyrin (CoTMPP) has been applied as a promising alternative method to the conventional heat treatment in order to attain highly active catalysts for the electroreduction of oxygen. In this contribution it is shown that CoTMPP can be completely transformed into a carbon matrix by...

Titanium dioxide (TiO2) is widely considered to be a strongly n-type semiconductor due to its tendency for oxygen deficiency. In this work, however, room temperature p-type semiconductivity has been observed in rutile TiO2, as determined using surface photovoltage spectroscopy and cyclic voltammetry subsequent to controlled processing at elevated t...

In order to optimize catalysts for fuel cells they are characterized by electron tomography. This method provides unique insights into the nanometre structures of the metallic catalyst particles deposited on an electrically conducting inert carbon support. The three-dimensional imaging method does not only allow for qualitative investigations, but...

A flexible, thin film Cu In,Ga Se2 solar cell deposited on a titanium foil was combined with a TiO2 photocatalyst layer and modified by a niobium doped titanium oxide front electrode to function as a photoelectrochemical tandem cell membrane for a direct light driven hydrogen evolution from aqueous solution. The P680 P700 tandem system in the plant...

In this contribution, catalysts, prepared by an impregnation technique have been characterized structurally and chemically via 57Fe Mö bauer spectroscopy, X ray photoelectron spectroscopy XPS and by elemental analysis, respectively. On the basis of the structural characterization it was concluded that those FeN4 centres in which iron is mesomericly...

Pyrolysis of chloroiron tetramethoxyphenyl porphyrin FeTMPP Cl in the presence of iron oxalate sulphur leads to the formation of higly porous and active catalysts for the oxygen reduction reaction ORR . In order to clarify the influence of sulphur the pyrolysis process is analyzed by thermogravimetry TG and by high temperature X ray diffraction HT...

Nine non-noble-metal catalysts (NNMCs) from five different laboratories were investigated for the catalysis of O(2) electroreduction in an acidic medium. The catalyst precursors were synthesized by wet impregnation, planetary ball milling, a foaming-agent technique, or a templating method. All catalyst precursors were subjected to one or more heat...

The utilisation of different metal oxalates in the pyrolysis of cobalt tetramethoxyphenylporphyrin CoTMPP has been investigated as a structure forming agent to obtain highly active electrocatalysts for the oxygen reduction reaction ORR . Decomposition products of the metal oxalates provide a nano scaled template for the carbonisation of CoTMPP. Aft...

The following work presents the preparation and investigation of pyrolysed Co porphyrin as an electrocatalyst for the oxygen reduc tion reaction ORR in acid media. A new preparation method which needs no addition of carbon supports, allows the structural investigation of the pyrolysis products by XPS, Raman spectro scopy and X ray diffractometry wi...

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Porphyrin based catalysts were prepared by the pyrolysis of transition metal macrocycles in the presence of iron oxalate as foaming agent and by the addition of sulfur. Characterization was performed using N2 and H2O sorption measurements, XPS, Raman and 57Fe Mö bauer spectroscopy, RRDE and PEM Fuel Cell experiments. ORR activity of already pyrolys...

The following work presents the preparation and investigation of pyrolysed Co porphyrine as an electrocatalyst for the oxygen reduction reaction ORR in acid media. A new preparation method which needs no addition of carbon supports, allows the structural investigation of the pyrolysis products by XPS, Raman spectroscopy and X ray diffractometry wit...

In this work it has been shown that structural changes of an as prepared catalyst enable the assignment of the catalytic centers responsible for the direct and indirect oxygen reduction reaction, respectively, of porphyrin based electrocatalysts. An iron porphyrin FeTMPPCl based catalyst as well as a catalyst based on H2TMPP were prepared using the...

Selenium modified ruthenium nano-particles are of interest as methanol tolerant electro-catalysts replacing the rare and expensive platinum at the cathode side of low-temperature Direct Methanol Fuel Cells. Recently, it has been found that both the activity and the oxidation resistance of ruthenium can be improved significantly by selenium. The str...

Ruthenium nano-particles modified by selenium were investigated in the last decade as an alternative to platinum which is used as electro-catalyst in fuel cell cathodes. In order to achieve highly loaded Ru-Se catalysts in a well dispersed and active state, selected parameters of the preparation procedure were optimised, such as the morphology and...

WO3-modified carbon-supported bi-component ruthenium–selenium, RuSex (Ru, 20; Se, 1 wt%), nanoparticles were dispersed in the form of Nafion-containing inks on glassy carbon electrodes to produce electrocatalytic interfaces reactive towards electroreduction of dioxygen in acid medium (0.5 mol dm−3 H2SO4). It was apparent from the rotating disk volt...

Carbon supported Rux Sey Oz catalysts were prepared from Ru3(CO)12 and RuCl3 · xH2O as ruthenium precursors and H2SeO3 and SeCl4 as the selenium sources. Highly active catalysts for the oxygen reduction reaction (ORR) in direct methanol fuel cells (DMFC) were obtained via a multi-step preparation procedure consisting of a CO2-activation of the carb...

Reductive annealing was chosen as a method for the syntheses of Se modified Ru C catalysts. Initial preparation of a 20 wt Ru C was performed by impregnating RuCl3.2H2O on Vulcan XC72 with subsequent conditioning using H2 at 250 C for 4 h. Surface treatment of Ru C by SeO2 followed by reductive annealing produced Se modified Ru C catalysts having R...

Particles on particles on particles : RuSexOx electrocatalysts with a cluster-like distribution of selenium on the surface of carbon-black-supported ruthenium nanoparticles are suitable replacements for platinum at the cathode side of methanol fuel cells. Carbon-supported RuSe xOy nanoparticles are not completely covered by Se after reductive annea...

Partikel auf Partikeln auf Partikeln Hoch aktive RuSexOy C Katalysatoren für die Sauerstoffreduktion sind durch ihre Methanoltoleranz prinzipiell geeignet, Platin auf der Kathodenseite von Methanol Brennstoffzellen zu ersetzen. Nach dem reduktiven Ausheizen bei 800 C sind die Ru Nanoteilchen nicht vollständig von Se bedeckt, sondern es liegen Se Cl...

of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007

An electrocatalytic system that utilizes tungsten oxide modified carbon-supported RuSex nanoparticles is developed and characterized here using transmission electron microscopy and such electrochemical diagnostic techniques as cyclic voltammetry and rotating ring-disk voltammetry, as well as upon its introduction (as cathode) to the low-temperature...

Plasma techniques have been extensively utilized in catalysis. Catalyst preparation using plasma treatment allows improving dispersion, enhancing catalyst performance and stability. In this paper, the low pressure RF discharge is shown as an efficient method to enhance activity of Co based electrocatalyst for the reduction of hydrogen peroxide. It...

It was earlier discovered that oxide layers conditioned with polymers and metal salts could be used as photographic materials producing a pronounced direct blackening when exposed to UV-light. In this paper the UV-induced blackening process in such layers is investigated and the mechanism of the underlying process is discussed. The possibility of a...

Introduction of carbon-supported RuSex nanoparticles or cobalt protoporphyrin into ultra-thin WO3 matrices results in the enhancement of their electroctalytic properties towards electroreduction of dioxygen in acidic medium (0.5 mol dm-3 H2SO4). The enhancement effects are evidenced from the positive shifts of the O2 reduction potentials (ca 150 mV...

Journal article

Cathode catalyst layers were prepared and characterized as part of membrane electrode assemblies (MEA) and catalyst coated membranes (CCM) on the basis of carbon supported methanol tolerant RuSex catalysts. Preparation parameters varied were: catalyst loading (0.5–2 mg RuSex cm−2), PTFE content (0, 6, 18 wt.%), carbon support (Vulcan XC 72 or BP200...

Ruthenium catalysts modified by selenium are of interest as a methanol insensitive oxygen reduction catalyst in a polymer electrolyte membrane fuel cell for mobile application. To elucidate the structural and chemical features of unsupported and carbon supported ruthenium nanoparticles prepared by thermolysis of Ru(3)(CO)(12) in an organic solvent...

A tailor made horseradish peroxidase HRP bulk composite electrode was developed on the basis of pyrolyzed cobalt tetramethoxyphenylporphyrin CoTMPP by modifying pore size and surface area of the porous carbon material through varying amounts of iron oxalate and sulfur prior to pyrolyzation. The materials were used to immobilize horseradish peroxida...

Nanocrystalline titanium oxinitride ( Ti O 2 − 2 x N x ) thin films ( 0 ⩽ x ⩽ 1 ) were prepared by reactive dc magnetron sputtering from a titanium target in an argon-oxygen-nitrogen atmosphere. By increasing the reactive gas component nitrogen the phases changed from Ti O 2 to Ti O 2 − 2 x N x and finally to TiN. The reactively sputteredfilms were...

Novel oxygen reduction electrocatalysts are obtained by thermo lysis of chelates such as cobalt tetramethoxy phenyl porphyrin CoTMPP in presence of the foaming agent FeC2O4. EXAFS spectra point to the presence of molecular Fe N4 and Co N4 centres embedded in a graphite like matrix. The foaming agent provokes the generation of a porous material 800...

Ruthenium catalysts were prepared employing aqueous solutions of ruthenium salts as precursors to obtain 2 nm sized metal particles homogeneously dispersed on a CO2 activa ted carbon support after annealing in hydrogen at 200 C. Selenium treatment was per form ed pouring the reduced product into a H2SeO3 or a SeCl4 solution prior to reduction in hy...

The performance of oxygen reduction catalysts (platinum, pyrolyzed iron(ll) phthalocyanine (pyr-FePc) and cobalt tetramethoxyphenylporphyrin (pyr-CoTMPP)) is discussed in light of their application in microbial fuel cells. It is demonstrated that the physical and chemical environment in microbial fuel cells severely affects the thermodynamics and t...

Modification of carbon-supported RuSex nanoparticles with ultra-thin WO3 films results in the enhancement of their electrocatalytic properties towards electroreduction of dioxygen in acid medium (0.5moldm−3 H2SO4) as evidenced from the positive shift of the O2 reduction potential (ca. 150mV) and the higher heterogeneous rate constant (ca. 3 times)....

Carbon supported ruthenium-based catalysts (Ru/C) for the oxygen reduction in acid electrolytes were investigated. A treatment of Ru/C catalysts with selenious acid had a beneficial effect on catalytic activity but no influence on intrinsic kinetic properties, like Tafel slope and hydrogen peroxide generation. Reasons for the increased activity of...

The performance of iron II phthalocyanine FePc and cobalt tetramethoxyphenylporphyrin CoTMPP based oxygen reduction catalysts was studied in view of the application as cathode materials in microbial fuel cells. Galvanostatic and potentiostatic experiments were performed in order to compare the proposed materials to platinum and hexacyanoferrate III...

Carbon-doped TiO2, demonstrated as an efficient photocatalyst in visible light photooxidation of organic compounds, was prepared with different doping concentrations and investigated via differential electrochemical mass spectroscopy (DEMS) and capacitive surface photovoltage (SPV) measurements in the form of thin layer electrodes. In all cases the...

Oxygen reduction catalysts have been prepared by modifying Ru/C catalysts (either commercial or self-made) using iron phenanthroline complexes adsorbed at the surface of the catalysts and heat treated at elevated temperatures. This new type of catalyst shows an oxygen reduction activity which is 3–5 times higher than the activity of an unmodified R...

Heat treated cobalt tetramethoxyphenylporphyrin CoTMPP on carbon support Black Pearls is well known as highly active material for the electroreduction of oxygen in acidic electrolytes. However, in the process of catalyst formation at high temperatures aggregation of the carbon supported particles occurs causing a detrimental decrease of the active...

Surface mesoscopic titanium dioxide (P25) films deposited onto conducting glass plates (SnO2:F) were modified by colloidal RuxSey nanoparticles (2 nm diameter). A decrease of the photocurrent was found upon modification of TiO2 films. However, interfacial electron transfer kinetics to oxygen was favored. The increase of the catalyst surface concent...