A novel approach to pulsed laser deposition of platinum catalyst on carbon particles for use in polymer electrolyte membrane fuel cells

• Bogusław Budner,
• Wojciech Tokarz,
• Sławomir Dyjak,
• Andrzej Czerwiński,
• Bartosz Bartosewicz and
• Bartłomiej Jankiewicz

Beilstein J. Nanotechnol. 2023, 14, 190–204, doi:10.3762/bjnano.14.19

• ; ORR; PEMFCs; PLD deposition; Pt catalyst; rotating ring-disk electrode (RRDE); SEM; TEM; XPS; Introduction Fuel cells, which cleanly and efficiently convert the chemical energy of hydrogen or other fuels to electrical energy, are a good alternative to dirty and wasteful combustion engines for

• commonly used catalyst in PEMFCs is platinum on various carbon support materials, which is used in both the anode and cathode because of its high catalytic activity toward the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) [6][17][18][19][21][22][23][24][25]. Pt is also characterized

• (Figures 4b and 4c). This observation is confirmed by the almost identical shape of the Pt 4f band (the same position and width of the peaks) for sample A and the reference catalyst 20% Pt XC-72R (Table 1). RRDE measurements of ORR activity of Pt catalysts The activity of the obtained Pt-based catalysts

Electrocatalytic oxygen reduction activity of AgCoCu oxides on reduced graphene oxide in alkaline media

• Iyyappan Madakannu,
• Indrajit Patil,
• Bhalchandra Kakade and
• Kasibhatta Kumara Ramanatha Datta

Beilstein J. Nanotechnol. 2022, 13, 1020–1029, doi:10.3762/bjnano.13.89

• the oxygen reduction reaction (ORR) in alkaline medium. Varying the Ag fraction in copper cobalt oxide has a significant influence on the ORR activity. At a ratio of 2:1:1, AgCuCo oxide NPs on rGO displayed the best values for onset potential, half-wave potential, and limiting current density (Jk) of

• environmentally friendly with zero emissions at the time of use. These systems have the ability to convert chemical energy into electric energy with the highest conversion possible [1][2]. The active electrode reactions include the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR). The

• slow reaction rates of the electrode processes impede the efficiency and, thus, require innovative catalyst designs. The ORR is an irreversible, complex (involving multiple steps and intermediates O, OH−, O2−, HO2− and H2O2) and kinetically slow process (via two- or four-electron transfer) dominating

Nanoarchitectonics of the cathode to improve the reversibility of Li–O₂ batteries

• Hien Thi Thu Pham,
• Jonghyeok Yun,
• So Yeun Kim,
• Sang A Han,
• Jung Ho Kim,
• Jong-Won Lee and
• Min-Sik Park

Beilstein J. Nanotechnol. 2022, 13, 689–698, doi:10.3762/bjnano.13.61

• containing a Li+-conductive aprotic electrolyte. In principle, electrochemical reactions between Li+ and O2 take place in the cathode to store and convert energy. During the discharge, the oxygen reduction reaction (ORR) occurs at the surface of the cathode, where O2 is spontaneously reduced by Li+ coming

• explored as advanced cathode materials for LOBs, owing to their controllable pore structure with a high surface-to-volume ratio and excellent electrical conductivity [13][14]. In particular, nitrogen-doped carbon materials have shown electrocatalytic activity towards the ORR and/or OER, which would be a

Sputtering onto liquids: a critical review

• Anastasiya Sergievskaya,
• Adrien Chauvin and
• Stephanos Konstantinidis

Beilstein J. Nanotechnol. 2022, 13, 10–53, doi:10.3762/bjnano.13.2

The effect of cobalt on morphology, structure, and ORR activity of electrospun carbon fibre mats in aqueous alkaline environments

• Markus Gehring,
• Tobias Kutsch,
• Osmane Camara,
• Alexandre Merlen,
• Hermann Tempel,
• Hans Kungl and
• Rüdiger-A. Eichel

Beilstein J. Nanotechnol. 2021, 12, 1173–1186, doi:10.3762/bjnano.12.87

• overall performance [3]. The lack of discharge performance is attributed to the sluggish kinetics of the oxygen reduction reaction (ORR) at the air cathode [4], which reduces the practical power density. Further improvements of the cathode are essential for the long-term success of metal–air batteries

• . Many researchers focus on the active material, that is, the catalyst, which enhances the ORR, and many promising systems have been reported and extensively reviewed [5]. The electrode scaffold receives far less attention. Only few reports elaborate on the importance of the electrode architecture for

• cobalt salt to the spinning solution [19][20][21][22]. Li et al. [19] investigated the activity of the material using a rotating ring disc and dilute 0.1 M KOH electrolyte. They found that the cobalt species were active in both oxygen evolution reaction (OER) and ORR. They also found that increasing

Stability and activity of platinum nanoparticles in the oxygen electroreduction reaction: is size or uniformity of primary importance?

• Kirill O. Paperzh,
• Anastasia A. Alekseenko,
• Vadim A. Volochaev,
• Ilya V. Pankov,
• Olga A. Safronenko and
• Vladimir E. Guterman

Beilstein J. Nanotechnol. 2021, 12, 593–606, doi:10.3762/bjnano.12.49

• liquid-phase synthesis. A comparative study of the structural characteristics, catalytic activity in the oxygen electroreduction reaction (ORR), and durability of the synthesized catalysts, as well as their commercial analogs, was carried out. It was shown that the uniformity of the structural and

• morphological characteristics of Pt/C catalysts makes it possible to reduce the negative effect of the small size of NPs on their stability. As a result, the obtained catalysts were significantly superior to their commercial analogs regarding ORR activity, but not inferior to them in terms of stability

• friendliness, low operating temperature, and high adaptability of specific characteristics [1][2][3]. The key components of PEMFC membrane–electrode assemblies (MEA) are the proton-exchange polymer membrane and porous electrode layers, in which current-forming reactions of oxygen electroreduction (ORR) and

Self-standing heterostructured NiC_x-NiFe-NC/biochar as a highly efficient cathode for lithium–oxygen batteries

• Shengyu Jing,
• Xu Gong,
• Shan Ji,
• Linhui Jia,
• Bruno G. Pollet,
• Sheng Yan and
• Huagen Liang

Beilstein J. Nanotechnol. 2020, 11, 1809–1821, doi:10.3762/bjnano.11.163

• carbon is a promising cathode material for lithium–oxygen batteries. Keywords: electrocatalytic performance; lithium–oxygen batteries; N-doped carbon; nickel carbide; oxygen evolution reaction (OER); oxygen reduction reaction (ORR); specific capacity; Introduction Clean and sustainable renewable energy

• , constant, on-demand, and reliable manner [3][4][5][6]. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play critical roles in many clean energy storage and conversion devices (e.g., hydrogen produced from water splitting via water electrolyzers, hydrogen fuel cells, and metal–air

• batteries [7][8][9][10]). In order to meet the requirements for efficient catalysts in practical applications, platinum group metal (PGM)-based catalysts are currently used as principal catalysts to reduce the overpotential of ORR and OER due to their slow kinetics [11][12][13]. The high cost, poor

One-step synthesis of carbon-supported electrocatalysts

• Sebastian Tigges,
• Nicolas Wöhrl,
• Ivan Radev,
• Ulrich Hagemann,
• Markus Heidelmann,
• Thai Binh Nguyen,
• Stanislav Gorelkov,
• Stephan Schulz and
• Axel Lorke

Beilstein J. Nanotechnol. 2020, 11, 1419–1431, doi:10.3762/bjnano.11.126

• electrochemical characteristics has been extensively studied in the literature [16][23], the unique synthesis method presented here is expected to influence both the electrochemically active surface area (ECSA), oxygen reduction reaction (ORR) mass activites and stability of the catalytically active Pt-NP, due to

• the aforementioned embedding. Therefore, Pt/CNW samples with different physical properties were studied concerning their ECSA, ORR mass activity and long-term stability, and the results were compared to those obtained with a commercially available Pt/C electrocatalyst. In Figure 7, the calculated ECSA

• , initial value. Additionally, we have measured ORR mass activities of the Pt/CNW samples relative to those of the commercial catalyst with a rotating disk electrode at 1600 rpm. Initially, after 0 AST cycles, none of the Pt/CNW samples are able to reach the activity of HiSPEC4000 with the best sample (CV2

Atomic layer deposition for efficient oxygen evolution reaction at Pt/Ir catalyst layers

• Stefanie Schlicht,
• Korcan Percin,
• Stefanie Kriescher,
• André Hofer,
• Claudia Weidlich,
• Matthias Wessling and
• Julien Bachmann

Beilstein J. Nanotechnol. 2020, 11, 952–959, doi:10.3762/bjnano.11.79

• intermittency of renewable energy sources such as solar and wind power [1][2][3]. The water oxidation (oxygen evolution reaction, OER) and its reverse, the oxygen reduction reaction (ORR) represent the limiting half-reaction of regenerative fuel cells [4][5], of some batteries (metal–air batteries) [6][7] and

• of some RFBs (such as the vanadium–air RFB). The positive electrode of these devices has to perform the challenging OER and ORR on one material system. A bimetallic Pt/Ir electrocatalyst is used most commonly as it provides minimal overpotentials under strongly acidic conditions [3][8][9][10]. The

• Ti as the electrode substrate with Pt and Ir as catalyst(s) is one of the few that ensure stability against the strongly acidic and oxidizing conditions of a reversible fuel cell. However, OER/ORR electrodes in some other electrochemical energy storage devices may have to endure even more harsh

Nickel nanoparticles supported on a covalent triazine framework as electrocatalyst for oxygen evolution reaction and oxygen reduction reactions

• Secil Öztürk,
• Yu-Xuan Xiao,
• Dennis Dietrich,
• Beatriz Giesen,
• Juri Barthel,
• Jie Ying,
• Xiao-Yu Yang and
• Christoph Janiak

Beilstein J. Nanotechnol. 2020, 11, 770–781, doi:10.3762/bjnano.11.62

• method. CTF-1-600 and Ni/CTF-1-600 show high catalytic activity towards OER and a clear activity for the electrochemical oxygen reduction reaction (ORR). Ni/CTF-1-600 requires 374 mV overpotential in OER to reach 10 mA/cm2, which outperforms the benchmark RuO2 catalyst, which requires 403 mV under the

• same conditions. Ni/CTF-1-600 displays an OER catalytic activity comparable with many nickel-based electrocatalysts and is a potential candidate for OER. The same Ni/CTF-1-600 material shows a half-wave potential of 0.775 V for ORR, which is slightly lower than that of commercial Pt/C (0.890 V

• ). Additionally, after accelerated durability tests of 2000 cycles, the material showed only a slight decrease in activity towards both OER and ORR, demonstrating its superior stability. Keywords: covalent triazine framework (CTF); electrocatalysis; nickel nanoparticles; oxygen evolution reaction; oxygen

Electrochemically derived functionalized graphene for bulk production of hydrogen peroxide

• Munaiah Yeddala,
• Pallavi Thakur,
• Anugraha A and
• Tharangattu N. Narayanan

Beilstein J. Nanotechnol. 2020, 11, 432–442, doi:10.3762/bjnano.11.34

• gaining tremendous attention due to its importance in many fields, including water treatment technologies. Oxidized graphitic carbon-based materials have been recently proposed as an alternative to metal-based catalysts in the electrochemical oxygen reduction reaction (ORR), and in this work we unravel

• graphene with tunable rate parameters, such as the rate constant and exchange current density. Higher oxygen-containing exfoliated graphene is known to undergo a two-electron reduction path in ORR having an efficiency of about 80 ± 2% even at high overpotential. Bulk production of H2O2 via electrolysis was

• method opens a new scheme for the single-step large-scale production of functionalized carbon-based catalysts (yield ≈45% by weight) that have varying functionalities and can deliver peroxide via the electrochemical ORR process. Keywords: electrochemical oxygen reduction; functionalized carbon

Synthesis of amorphous and graphitized porous nitrogen-doped carbon spheres as oxygen reduction reaction catalysts

• Maximilian Wassner,
• Markus Eckardt,
• Andreas Reyer,
• Thomas Diemant,
• Michael S. Elsaesser,
• R. Jürgen Behm and
• Nicola Hüsing

Beilstein J. Nanotechnol. 2020, 11, 1–15, doi:10.3762/bjnano.11.1

• Abstract Amorphous and graphitized nitrogen-doped (N-doped) carbon spheres are investigated as structurally well-defined model systems to gain a deeper understanding of the relationship between synthesis, structure, and their activity in the oxygen reduction reaction (ORR). N-doped carbon spheres were

• temperatures. The overall nitrogen content of the graphitized N-doped carbon spheres is lower than that of the amorphous carbon spheres, however, also the microporosity decreases strongly with graphitization. Comparison with the electrocatalytic behavior in the ORR shows that in addition to the N-doping, the

• microporosity of the materials is critical for an efficient ORR. Keywords: amorphous carbon; graphitized carbon; hydrothermal carbonization; nitridation; nitrogen doping; oxygen reduction reaction (ORR); porosity; Introduction Fuel cells and metal–air batteries are important renewable energy technologies

Synthesis of P- and N-doped carbon catalysts for the oxygen reduction reaction via controlled phosphoric acid treatment of folic acid

• Rieko Kobayashi,
• Takafumi Ishii,
• Yasuo Imashiro and
• Jun-ichi Ozaki

Beilstein J. Nanotechnol. 2019, 10, 1497–1510, doi:10.3762/bjnano.10.148

• oxygen reduction reaction (ORR) at the cathode of a fuel cell. Precursors obtained by heating FA in the presence of phosphoric acid at temperatures of 400–1000 °C were further annealed at 1000 °C to afford PN-doped carbon materials. The extent of precursor P doping was maximized at 700 °C, and the use of

• material prepared using a CPAT temperature of 700 °C exhibited the highest ORR activity and was shown to contain –C–PO2 and –C–PO3 moieties as the major P species and pyridinic N as the major N species. Moreover, no N–P bonds were detected. It was concluded that the presence of –C–PO2 and –C–PO3 units

• decreases the work function and thus raises the Fermi level above the standard O2/H2O reduction potential, which resulted in enhanced ORR activity. Finally, CPAT was concluded to be applicable to the synthesis of PN-doped carbon materials from N-containing organic compounds other than FA. Keywords: folic

Warped graphitic layers generated by oxidation of fullerene extraction residue and its oxygen reduction catalytic activity

• Machiko Takigami,
• Rieko Kobayashi,
• Takafumi Ishii,
• Yasuo Imashiro and
• Jun-ichi Ozaki

Beilstein J. Nanotechnol. 2019, 10, 1391–1400, doi:10.3762/bjnano.10.137

• Abstract Carbon-based oxygen reduction reaction (ORR) catalysts are regarded as a promising candidate to replace the currently used Pt catalyst in polymer electrolyte fuel cells (PEFCs); however, the active sites remain under discussion. We predicted that warped graphitic layers (WGLs) are responsible for

• the ORR catalytic activity in some carbon catalysts (i.e., carbon alloy catalysts (CACs)). To prove our assumption, we needed to use WGLs consisting of carbon materials, but without any extrinsic catalytic elements, such as nitrogen, iron, or cobalt, which effectively enhance ORR activity. The present

• 600 °C in an O2/N2 stream. Extending the oxidation time increased the purity of the WGL phase, but also simultaneously increased the concentration of oxygen-containing surface functional groups as monitored by temperature programmed desorption (TPD). The specific ORR activity increased with oxidation

Alloyed Pt₃M (M = Co, Ni) nanoparticles supported on S- and N-doped carbon nanotubes for the oxygen reduction reaction

• Stéphane Louisia,
• Yohann R. J. Thomas,
• Pierre Lecante,
• Marie Heitzmann,
• M. Rosa Axet,
• Pierre-André Jacques and
• Philippe Serp

Beilstein J. Nanotechnol. 2019, 10, 1251–1269, doi:10.3762/bjnano.10.125

• reaction (ORR) have been evaluated in a rotating ring disk electrode experiment. The Pt3M/N-CNT catalysts revealed excellent electrochemical properties compared to a commercial Pt3Co/Vulcan XC-72 catalyst. The nature of the carbon support plays a key role in determining the properties of the metal

• nanoparticles, on the preparation of the catalytic layer, and on the electrocatalytic performance in the ORR. On N-CNT supports, the specific activity followed the expected order Pt3Co > Pt3Ni, whereas on the annealed N-CNT support, the order was reversed. Keywords: carbon nanotubes; cobalt; ionic liquid

• ; nickel; oxygen reduction reaction; platinum; proton exchange membrane fuel cell (PEMFC); Introduction Proton exchange membrane fuel cells (PEMFCs) convert chemical energy from the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR) into electrical energy. PEMFCs are one of the most

Glucose-derived carbon materials with tailored properties as electrocatalysts for the oxygen reduction reaction

• Rafael Gomes Morais,
• Natalia Rey-Raap,
• José Luís Figueiredo and
• Manuel Fernando Ribeiro Pereira

Beilstein J. Nanotechnol. 2019, 10, 1089–1102, doi:10.3762/bjnano.10.109

• engines, as they are able to function as long as there is fuel, and for batteries, as they have similar characteristics under load conditions [1]. The performance of a fuel cell is mainly controlled by the oxygen reduction reaction (ORR) that takes place at the cathode [2], specifically by the

• materials [3][4] have been widely studied as electrocatalysts in ORR due to their attractive physical and electrochemical properties. Among these materials, metal-free carbon materials have received tremendous attention due to their versatility and lower price in comparison with metal-based materials [2

• ]. The main advantage of carbon materials is the possibility of modifying their physical and chemical properties resulting in a more electroactive material [2][3][10], which is an especially important feature for the ORR. The incorporation of heteroatoms like nitrogen [11][12], oxygen [13], sulfur [14

Metal-free catalysis based on nitrogen-doped carbon nanomaterials: a photoelectron spectroscopy point of view

• Mattia Scardamaglia and
• Carla Bittencourt

Beilstein J. Nanotechnol. 2018, 9, 2015–2031, doi:10.3762/bjnano.9.191

• ; photoelectron spectroscopy; Introduction Catalytic processes are the basis of many important technologies in the chemical industry and for energy generation, especially in the context of renewable, clean and sustainable energy production [1]. The oxygen reduction reaction (ORR) and the electrocatalytic

• -free catalyst for the ORR had not been considered feasible [9][10] until two fundamental milestones had risen the interest on carbon as an effective replacement of Pt for catalysis. The first one was the prediction of the remarkable electrical conducting properties of carbon nanotubes (CNTs) in 1993

• discovery of their catalytic performance in the ORR: beginning with nitrogen-doped carbon fibres (2006 [18]), followed by carbon nanotubes (2009 [19]) and finally graphene (2010 [20]). In 2006, Matter and Ozkan reported on a metal-free ORR catalyst containing nitrogen-doped carbon fibers. The authors

Synthesis of rare-earth metal and rare-earth metal-fluoride nanoparticles in ionic liquids and propylene carbonate

• Marvin Siebels,
• Lukas Mai,
• Laura Schmolke,
• Kai Schütte,
• Juri Barthel,
• Junpei Yue,
• Jörg Thomas,
• Bernd M. Smarsly,
• Anjana Devi,
• Roland A. Fischer and
• Christoph Janiak

Beilstein J. Nanotechnol. 2018, 9, 1881–1894, doi:10.3762/bjnano.9.180

• [23]. Rare-earth metal containing intermetallic nano-phases have been suggested as novel materials for various catalytic applications [24]. For example, Pt3Y and Pt5Gd were predicted to be more active as Pt in the oxygen reduction reaction (ORR) [25]. Nevertheless, the high reduction potentials of

Synthesis of graphene–transition metal oxide hybrid nanoparticles and their application in various fields

• Arpita Jana,
• Elke Scheer and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2017, 8, 688–714, doi:10.3762/bjnano.8.74

• and also to improve the volume change. In that context, graphene has been hybridised with Cr2O3 to improve the properties of the materials and the other strategy is to develop Cr2O3 materials on the nanoscale. Graphene–Cr2O3 hybrids have been explored with respect to the oxygen reduction reaction (ORR

• ) [118] and applications in energy storage [119]. ORR is the key step of renewable energy technologies including fuel cells and water splitting. For excellent electrocatalysts, one of the most important factors is long-term running stability. The long term running stability of the Cr2O3–rGO hybrid makes

• decomposition of methylene blue (MB) [127], for the catalytic decomposition of aqueous organics [128], for carbon dioxide adsorption [129], for ORR [130], for enhancing electrochemical performance for supercapacitors [131][132][133], and for catalytic oxidation and adsorption of elementary mercury [134]. Bag et

Orientation of FePt nanoparticles on top of a-SiO₂/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size

• Martin Schilling,
• Paul Ziemann,
• Zaoli Zhang,
• Johannes Biskupek,
• Ute Kaiser and
• Ulf Wiedwald

Beilstein J. Nanotechnol. 2016, 7, 591–604, doi:10.3762/bjnano.7.52

• transmission electron microscopy (HRTEM); nanoparticles; reflection high-energy electron diffraction (RHEED); solid-phase epitaxy; texture; Introduction Due to their attractive catalytic properties for oxygen reduction reactions (ORR) [1][2] as well as their high magnetocrystalline anisotropy energy density

Comprehensive characterization and understanding of micro-fuel cells operating at high methanol concentrations

• Aldo S. Gago,
• Juan-Pablo Esquivel,
• Neus Sabaté,
• Joaquín Santander and
• Nicolas Alonso-Vante

Beilstein J. Nanotechnol. 2015, 6, 2000–2006, doi:10.3762/bjnano.6.203

• cathode, at a given current density, decreases gradually, 0.88 to 0.6 V vs RHE, as the fuel concentration increases. The reason is that the fuel crossover effect (mixed-potential developed between the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR)) is more important [31]. The

• potential reaches ca. 1 V vs RHE, which corresponds to the (ORR) onset potential on the nanostructured Pt in acidic media. Over time, a mixed-potential is generated by the oxidation of CH3OH at the cathode, which negatively affects the voltage of the cell. The anode potential remained practically at 0.4 V

• drop in the cell voltage. The cathode potential was constant since the ORR occurs on the surface of the Pt catalyst and the oxidant (O2 from the air) is never depleted. During the fuel consumption it was observed that some CO2 bubbles randomly came out from the grid in the silicon current collector

From lithium to sodium: cell chemistry of room temperature sodium–air and sodium–sulfur batteries

• Philipp Adelhelm,
• Pascal Hartmann,
• Conrad L. Bender,
• Martin Busche,
• Christine Eufinger and
• Juergen Janek

Beilstein J. Nanotechnol. 2015, 6, 1016–1055, doi:10.3762/bjnano.6.105

• , lithium is oxidized at the negative electrode and oxygen is reduced on the positive electrode. Similar to a fuel cell cathode, the positive electrode is a porous, electron-conducting support (gas diffusion layer, GDL) that enables oxygen transport, oxygen reduction (ORR) and oxygen evolution (OER) during

• ORR/OER reactions in metal–air batteries is not sufficient as also plating/stripping of the alkali metal needs to be reversible in order to achieve a long cycle life. Cell discharge using this IL based electrolyte at 25 µA/cm2 was characterized by a sloping decrease, charging (250 µA/cm2) mainly

Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

• Roswitha Zeis

Beilstein J. Nanotechnol. 2015, 6, 68–83, doi:10.3762/bjnano.6.8

• specific adsorption of the phosphoric acid electrolyte is known to hamper the oxygen reduction reaction activity on the cathode side. Moreover, the low solubility and diffusivity of oxygen in concentrated phosphoric acid has a negative effect on the ORR [14][15]. These problems are specific to phosphoric

• higher than the typical Pt loading reported for LT-PEMFCs (0.1–0.4 mg/cm2). The high noble-metal loading is mainly accounted to the pure utilization of platinum because the electrolyte partially floods the catalyst layer. In addition, the anion adsorption impedes the ORR in concentrated phosphoric acid

Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

• Matthias Augustin,
• Daniela Fenske,
• Ingo Bardenhagen,
• Anne Westphal,
• Martin Knipper,
• Thorsten Plaggenborg,
• Joanna Kolny-Olesiak and
• Jürgen Parisi

Beilstein J. Nanotechnol. 2015, 6, 47–59, doi:10.3762/bjnano.6.6

• oxygen reduction reaction (ORR), linear sweep measurements were carried out. Figure 9 shows linear sweep measurements recorded at 50 mV/s comparing the activity of various 10% MnOx/carbon electrodes to a pure carbon electrode as a reference material for the ORR in aprotic electrolyte. The ORR peak

• of transferred electrons, F is the Faraday constant, and CO2 = 2.1∙10−6 mol cm−3 is the oxygen solubility in DMSO [39]. The mean ORR peak potential of the carbon reference material given in Table 2 is observed at 2.58 V. The only MnOx species with a significant increase of the ORR potential of 100 mV

• with respect to the carbon as well as the other MnOx/C electrodes is the mesoporous α-Mn2O3 catalyst. The obvious activity is reflected in the approximately four- and two-fold larger apparent ORR rate constant compared to the carbon and the other MnOx/C electrodes, respectively. A detailed kinetic and

Donor–acceptor graphene-based hybrid materials facilitating photo-induced electron-transfer reactions

• Anastasios Stergiou,
• Georgia Pagona and
• Nikos Tagmatarchis

Beilstein J. Nanotechnol. 2014, 5, 1580–1589, doi:10.3762/bjnano.5.170

• EDTA and re-complexes after fresh addition of Fe(II) (Scheme 2). Furthermore, Fe–tpy–GO was tested as a catalyst for the oxygen reduction reaction (ORR) and found to be durable against carbon monoxide poisoning and to exhibit a higher fuel selectivity compared with commercially available Pt/C electro

• -catalysts. The ORR reactivity is tightly connected to electron transfer processes, thus indicating indirectly the occurrence of such phenomena. Ruthenium(II) was also employed as a coordinating cation and resulted in a Ru–tpy–GO hybrid material with an enhanced photocurrent response, higher than GO and Fe