18.-21.11.2019UnOCat Lecture Series "Methods for Material Characterization and Computational Modelling"
In our first lecture series, there will be different talks about catalyst preparation, characterization, data evaluation as well as theoretical modelling.
More information can be found here.
04.-05.11.2019Joint Symposium "Nanomaterials for Energy Applications"
Together with CENIDE and the University of Tsukuba, CRC/TRR 247 is organizing the joint symposium on "Nanomaterials for Energy Applications" at NETZ in Duisburg.
More information can be found here.
16.10.2019Meeting on "Perovskites in Catalysis"
On 16th of October, we will review the current stage of research on perovskites in catalysis.
The meeting will take place in Mülheim at the MPI CEC . The agenda is available here.
30.09.-02.10.2019Autumn School 2019 on “Leadership and Career“
The autumn school is organised by CRC/TRR 247 and CRC 1093.
There will be a keynote speech of Dr. Gaby Schilling about „Leadership and Diversity – the Key to Excellence“, several workshops and individual coachings about leadership, project management and career planning.
The programme is available here.
27.09.2019Twitter: SEC lab MPI CEC
02.-04.09.20191. PhD Retreat
The first UnOCat retreat will take place at Kinder- und Jugendcamp Haard e.V., Haardgrenzweg 200, Oer-Erkenschwick and will start on September 2nd in the afternoon and ends on September 4th after breakfast.
NATURE CAREER FEATUREMeeting the challenges of research across Africa
Dr. Stéphane Kenmoe, computational chemist at the University of Duisburg-Essen, talks about career implications of developing his research in Cameroon. His goal is "is to build an army of science champions — not just researchers but also journalists, actors and athletes — who will promote science wherever possible."
> more about: https://www.nature.com/articles/d41586-019-02311-2
Publication alertPerspective of surfactant-free colloidal nanoparticles in heterogeneous catalysis
Due to material gaps and synthesis-related cross-correlations in heterogeneous catalysis, chemists and physicists are constantly motivated to develop novel catalyst preparation methods for independent control of morphology, size, and composition. Within this article, advances, opportunities, and the current limits of laser-based catalyst preparation technique, as well as synergies with conventional methods will be reviewed in terms of purity, particle size, morphology, composition, and nanoparticle-support interaction. It will be shown, that the surfactant-free particles represent ideal model materials to validate kinetic models and conduct parametric activity-studies by independent adjustment of functional properties like nanoparticle size, composition, and load. Consequently, the importance of transient plasma dynamics tailoring nanoparticle formation will be pointed out, comparing experimental studies with own calculations and novel simulations taken from literature. Finally, perspectives of surfactant-free colloidal nanoparticles for unrevealing active sites in heterogeneous catalysts are presented.
Reichenberger, S., Marzun, G., Barcikowski, S., Muhler, M.: Perspective of surfactant‐free colloidal nanoparticles in heterogeneous catalysis, ChemCatChem 2019, https://doi.org/10.1002/cctc.201900666
Publication alertHigh reaction rates even without precious metals
Non-precious metal nanoparticles could one day replace expensive catalysts for hydrogen production. However, it is often difficult to determine what reaction rates they can achieve, especially when it comes to oxide particles. This is because the particles must be attached to the electrode using a binder and conductive additives, which distort the results.
With the aid of electrochemical analyses of individual particles, researchers have now succeeded in determining the activity and substance conversion of nanocatalysts made from cobalt iron oxide – without any binders.
> more about: Press Release Ruhr-University Bochum, 19.06.2019
We focus on the application of advanced #materials characterisation techniques for the development of new functional and structural materials. ^tl— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019
Publication alertIntrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe2O4 Nanoparticles
Identifying the intrinsic electrocatalytic activity of nanomaterials is challenging, as their characterization usually requires additives and binders whose contributions are difficult to dissect. Herein, we use nano impact electrochemistry as an additive-free method to overcome this problem. Due to the efficient mass transport at individual catalyst nanoparticles, high current densities can be realized. High-resolution bright-field transmission electron microscopy and selected area diffraction studies of the catalyst particles before and after the experiments provide valuable insights in the transformation of the nanomaterials during harsh oxygen evolution reaction (OER) conditions. We demonstrate this for 4 nm sized CoFe2O4 spinel nanoparticles. It is revealed that these particles retain their size and crystal structure even after OER at current densities as high as several kA·m–2. The steady-state current scales with the particle size distribution and is limited by the diffusion of produced oxygen away from the particle. This versatilely applicable method provides new insights into intrinsic nanocatalyst activities, which is key to the efficient development of improved and precious metal-free catalysts for renewable energy technologies.
El Arrassi, A., Liu, Z., Evers, M.V., Blanc,N., Bendt, G., Saddeler, S., Tetzlaff, D., Pohl, D., Damm, C., Schulz, S., Tschulik, K.: Intrinsic Activity of Oxygen Evolution Catalysts Probed at Single CoFe2O4 Nanoparticles, Journal of the American Chemical Society 2019, https://doi.org/10.1021/jacs.9b04516
Prof. Dr. Wolfgang Schuhmann honored for his research Giulio Milazzo Prize of BES
The Bioelectrochemical Society (BES) honored the research work of Prof. Dr. Wolfgang Schuhmann, Ruhr-University Bochum, with the Giulio Milazzo Price at the biannual BES Symposium 2019 in Limerick, Ireland, where he gave the "Giulio Milazzo Prize" lecture.
Publication alertSelective 2‑Propanol Oxidation over Unsupported Co3O4 Spinel Nanoparticles: Mechanistic Insights into Aerobic Oxidation of Alcohols
Crystalline Co3O4 nanoparticles with a uniform size of 9 nm as shown by XRD and TEM were synthesized by thermal decomposition of cobalt acetylacetonate in oleylamine and applied in the oxidation of 2-propanol after calcination. The catalytic properties were derived under continuous flow conditions as a function of temperature up to 573 K in a fixed-bed reactor at atmospheric pressure. Temperature-programmed oxidation, desorption (TPD), surface reaction (TPSR), and 2-propanol decomposition experiments were performed to study the interaction of 2-propanol and O2 with the exposed spinel surfaces. Co3O4 selectively catalyzes the oxidative dehydrogenation of 2-propanol, yielding acetone and H2O and only to a minor extent the total oxidation to CO2 and H2O at higher temperatures. The high catalytic activity of Co3O4 reaching nearly full conversion with 100% selectivity to acetone at 430 K is attributed to the high amount of active Co3+ species at the catalyst surface as well as surface-bound reactive oxygen species observed in the O2 TPD, 2-propanol TPD, TPSR, and 2-propanol decomposition experiments. Density functional theory calculations with a Hubbard U term support the identification of the 5-fold-coordinated octahedral surface Co5c3+ as the active site, and oxidative dehydrogenation involving adsorbed atomic oxygen was found to be the energetically most favored pathway. The consumption of surface oxygen and reduction of Co3+ to Co2+ during 2-propanol oxidation derived from X-ray absorption spectroscopy and X-ray photoelectron spectroscopy measurements before and after reaction and poisoning by strongly bound carbonaceous species result in the loss of the low-temperature activity, while the high-temperature reaction pathway remained unaffected.
Anke, S., Bendt, G., Sinev, I., Hajiyani, H., Antoni, H., Zegkinoglou, I., Jeon, H., Pentcheva, R., Roldan Cuenya, B., Schulz, S., Muhler, M.: Selective 2‑Propanol Oxidation over Unsupported Co3O4 Spinel Nanoparticles: Mechanistic Insights into Aerobic Oxidation of Alcohols, ACS Catalysis 2019, 9, 5974-5985.
Publication alertLife cycle of tiny catalyst particles observed
Individual nanoparticles are very difficult to investigate, because they are extremely small. But that is the goal of the scientists to later be able to customise their properties. The new approach: 'particle at a stick'.
Harshitha Barike Aiyappa, Patrick Wilde, Thomas Quast, Justus Masa, Corina Andronescu, Yen-Ting Chen, Martin Muhler, Roland A. Fischer, Wolfgang Schuhmann: Oxygen evolution electrocatalysis of a single MOF‐derived composite nanoparticle on the tip of a nanoelectrode, Angewandte Chemie International Edition 2019, DOI: 10.1002/anie.201903283
Catalysts for controlled cascade reactions ERC Advanced Grant
Prof. Dr. Wolfgang Schuhmann received an European Research Council (ERC) Advanced Grant to study the conversion of harmful gases into useful basic chemicals on an industrial scale. For this purpose, he is getting 2.5 Mio. € for the next 5 years.
> more about: Press Release Ruhr-University Bochum, 28.03.2019
07.03.2019First UnOCat Assembly
Our first assembly of the CRC/TRR 247 graduate school UnOCat "Understanding Oxidation Catalysis" took place at the RUB on 7th of March.
Doctoral researchers in CRC/TRR 247 discussed their work and elected Anna Rabe as their PhD representative as well as Steven Angel as her deputy.
Publication alertSpray‐Flame‐Synthesized LaCo1−xFexO3 Perovskite Nanoparticles as Electrocatalysts for Water and Ethanol Oxidation
Spray-flame synthesized LaCo1-xFexO3 perovskites show promising electrocatalytic activity towards the oxygen evolution reaction and ethanol electrooxidation. The selectivity of the ethanol oxidation reaction is influenced by the Fe content, with acetic aldehyde being detected on Fe rich perovskites while acetate is generated on the Fe free catalysts up to potentials of 1.7 V vs. RHE.
Alkan, B., Cychy, S., Varhade, S., Muhler, M., Schulz, C., Schuhmann, W., Wiggers, H., Andronescu, C.: Spray‐Flame‐Synthesized LaCo1−xFexO3 Perovskite Nanoparticles as Electrocatalysts for Water and Ethanol Oxidation, ChemElectroChem 2019, 6, 1-10.
11.02.2019EMPOWER dinner for female early career scientists
On 11th of February, the international day of women and girls in science, young female scientists of CRC/TRR 247 met in Essen for an informal networking event. Together, they discussed the CRC/TRR 247 support of female scientists in their academic qualifications and career developments.
Publication alertSynergistic effects of Mo2C‐NC@FexCoy core‐shell nanoparticles in electrocatalytic overall water splitting reaction
The scientists report on the synthesis of bimetallic CoxFey alloy nanoparticles encapsulated in an N‐doped graphene shell containing molybdenum carbide (Mo2C) nanoparticles, which are obtained by the pyrolysis of cobalt ferrite CoxFe3‐xO4 nanoparticles coated by molybdic acid‐cross‐linked melamine‐formaldehyde (MF) resin. Molybdic acid not only serves as precursor for the formation of highly dispersed Mo2C nanoparticles in the N‐doped graphene shell but also enhances the thermal stability of the organic shell, resulting in the formation of smaller CoxFey cores. The formation of Mo2C nanoparticles in the graphene shell is promoted by the cobalt ferrite core. Interestingly, the synergistic presence of Mo2C nanoparticles not only enhances the HER activity of the material, but also renders a partial breakage of the graphene shell which increases the surface concentration of OER active Co and therefore enhances the OER activity. The as‐prepared TMs‐based materials serve as bi‐functional catalysts for the overall water splitting and exhibit improved electrocatalytic performances compared to standard cells based on precious metals, with potentials of 1.53 V and 1.60 V at 10 mA cm‐2 and 20 mA cm‐2, respectively.
Wang, S., Bendt, G., Saddeler, S., Schulz, S.: Synergistic Effects of Mo2C‐NC@CoxFey Core–Shell Nanoparticles in Electrocatalytic Overall Water Splitting Reaction, Energy Technology 2019, 7, DOI: 10.1002/ente.201801121.
New CRC/TRR 247 projectProf. Dr. Wolfgang Kleist joins CRC/TRR 247
The new project C6 "Metal‐organic frameworks as molecularly defined single‐site catalysts and precursor species for bimetallic Co/Fe materials in liquid phase oxidation reactions" aims at the development of single‐site catalysts based on metal‐organic frameworks (MOFs) containing well‐defined Co and Fe species in their framework structures.
Materials Research SocietyBest Poster Award for Steven Angel
Steven Angel, PhD candidate in project C2, received the Best Poster Award at the "Nanomaterials and Nanomanufacturing for Sustainability Symposium" at the Materials Research Society conference in Boston in November 2018.
His poster entitled „Spray-flame synthesis of nanosized LaMO3 (M = Fe, Co) perovskites for CO oxidation” is presenting results of his work with two solvents (Ethanol and 2-Ethylhexanoic acid) and their influence on spray-flame synthesis of the perovskites LaFeO3 and LaCoO3.
Happy HolidaysChristmas greetings
Greetings of the season and our best wishes for a prosperous New Year 2019!
UA RuhrJoint platform for catalysis research
Prof. Dr. Malte Behrens will continue his work in teaching and research with a UA Ruhr professorship in "Materials Chemistry of Catalysts" at the faculty of chemistry, University Duisburg-Essen and at the faculty of chemistry and biochemistry, Ruhr-University Bochum.
Successful start in DuisburgKick-off meeting
In total 74 scientists, including project leaders, but also young researchers, participated in our kick-off meeting in Duisburg on 4th/5th of December 2018.
> more about: Press Release CENIDE, 17.12.2018
Publication alertCobalt metalloid and polybenzoxazine derived composites for bifunctional oxygen electrocatalysis
The development of bifunctional oxygen electrodes is a key factor for the envisaged application of rechargeable metal-air batteries. In this work, we present a simple procedure based on pyrolysis of polybenzoxazine/metal metalloid nanoparticles composites into efficient bifunctional oxygen reduction and oxygen evolution electrocatalysts. This procedure generates nitrogen-doped carbon with embedded metal metalloid nanoparticles exhibiting high activity towards both, oxygen reduction and oxygen evolution, in 0.1 M KOH with a roundtrip voltage of as low as 0.81 V. Koutecký-Levich analysis coupled with scanning electrochemical microscopy reveals that oxygen is preferentially reduced in a 4e− transfer pathway to hydroxide rather than to hydrogen peroxide. Furthermore, the polybenzoxazine derived carbon matrix allows for stable catalyst fixation on the electrode surface, resulting in unattenuated activity during continuous alternate polarisation between oxygen evolution at 10 mA cm−2 and oxygen reduction at −1.0 mA cm−2.
Barwe, S., Andronescu, C., Engels, R., Conzuelo, F., Seisel, S., Wilde, P., Chen, Y.T., Masa, J., Schuhmann, W.: Cobalt metalloid and polybenzoxazine derived composites for bifunctional oxygen electrocatalysis, Electrochimica Acta 297, 1042-1051.
Publication alertSurface Termination and Composition Control of Activity of the CoxNi1−xFe2O4(001) Surface for Water Oxidation: Insights from DFT+U Calculations
Using density functional theory calculations with an on-site Hubbard term (DFT+U), we explore the effect of surface termination and cation substitution on the performance of the CoxNi1–xFe2O4(001) surface (x = 0.0, 0.5, 1.0) as an anode material in the oxygen evolution reaction (OER). Different reaction sites (Fe, Co, Ni, and an oxygen vacancy) were investigated at three terminations: the B-layer with octahedrally coordinated Co/Ni and with an additional half and full monolayer of Fe (0.5A and A-layer, respectively). Ni substitution with an equal concentration of Co and Ni (x = 0.5) reduces the overpotential over the end members for the majority of reaction sites. Surface Co cations are identified as the active sites and the ones at the A-layer termination for x = 0.5 exhibit one of the lowest theoretically reported overpotentials of 0.26 V. The effect of the additional iron layer on the active site modification is 2-fold: analysis of the electronic properties and spin densities indicates that the additional Fe layer stabilizes a bulk-like oxidation state of +2 for Co and Ni at the A-layer termination, whereas at the B-layer termination, they are oxidized to 3+. Moreover, the unusual relaxation pattern enables the formation of a hydrogen bond of the OOH intermediate to a neighboring surface oxygen that lowers the reaction free energy of this formerly rate-limiting step, leading to a deviation from the scaling relationship and almost equidistant reaction free-energy steps of intermediates. This renders an example of how a selective surface modification can result in a significant improvement of OER performance.
Hajiyani, H., Pentcheva, R.: Surface Termination and Composition Control of Activity of the CoxNi1–xFe2O4(001) Surface for Water Oxidation: Insights from DFT+U Calculations, ACS Catalysis 2018, 8 (12), 11773-11782.
Publication alertDiscovery of a Multinary Noble Metal–Free Oxygen Reduction Catalyst
Scientists at Ruhr-University Bochum show that noble metal-free catalysts are as active as platinum and provide a base to produce more efficient and less expensive catalysts.
> more about: Press Release Ruhr-University Bochum, 23.10.2018
Löffler, T., Meyer, H., Savan, A., Wilde, P., Garzón Manjón, A., Chen, Y.-T., Ventosa, E., Scheu, C., Ludwig, A., Schuhmann, W.: Discovery of a multinary noble metal free oxygen reduction catalyst, Advanced Energy Materials 2018, DOI: 10.1002/aenm.201802269
Prof. Dr. Wolfgang Schuhmann honored for his research Alessandro Volta Medal
The Electrochemical Society (ECS) honored the fundamental and applied research work of Prof. Dr. Wolfgang Schuhmann, Ruhr-University Bochum. He developed novel biosensors, redox polymers and materials for electrocatalysis and batteries. Congratulations!
> more about: Press Release Ruhr-University Bochum, 05.10.2018
Publication alertWhy Tin‐Doping Enhances the Efficiency of Hematite Photoanodes for Water Splitting—The Full Picture
The beneficial effects of Sn(IV) as a dopant in ultrathin hematite (α‐Fe2O3) photoanodes for water oxidation are examined. Different Sn concentration profiles are prepared by alternating atomic layer deposition of Fe2O3 and SnO x . Combined data from spectrophotometry and intensity‐modulated photocurrent spectroscopy yields the individual process efficiencies for light harvesting, charge separation, and charge transfer. The best performing photoanodes are Sn‐doped both on the surface and in the subsurface region and benefit from enhanced charge separation and transfer. Sn‐doping throughout the bulk of the hematite photoanode causes segregation at the grain boundaries and hence a lower overall efficiency. Fe2O3 (0001) and terminations, shown to be dominant by microstructural analysis, are investigated by density functional theory (DFT) calculations. The energetics of surface intermediates during the oxygen evolution reaction (OER) reveal that while Sn‐doping decreases the overpotential on the (0001) surface, the Fe2O3 orientation shows one of the lowest overpotentials reported for hematite so far. Electronic structure calculations demonstrate that Sn‐doping on the surface also enhances the charge transfer efficiency by elimination of surface hole trap states (passivation) and that subsurface Sn‐doping introduces a gradient of the band edges that reinforces the band bending at the semiconductor/electrolyte interface and thus boosts charge separation.
Hufnagel, A.G., Hajiyani, H., Zhang, S., Li, T., Kasian, O., Gault, B., Breitbach, B., Bein, T., Fattakhova-Rohlfing, D., Scheu, C., Pentcheva, R.: Why Tin‐Doping Enhances the Efficiency of Hematite Photoanodes for Water Splitting—The Full Picture, Advanced Functional Materials 2018, 28 (52), 1804472.
Publication alertMechanism of Laser-Induced Bulk and Surface Defect Generation in ZnO and TiO2 Nanoparticles: Effect on Photoelectrochemical Performance
Laser processing of neat and gold-nanoparticle-functionalized ZnO and TiO2 nanoparticles by nanosecond–355 nm or picosecond–532 nm light enabled control of photocurrent generation under simulated sunlight irradiation in neutral aqueous electrolytes. We obtained more than 2-fold enhanced photoelectrochemical performance of TiO2 nanoparticles upon irradiation by picosecond–532 nm pulses that healed defects. Laser processing and gold nanoparticle functionalization of ZnO and TiO2 nanomaterials resulted in color changes that did not originate from optical bandgaps or crystal structures. Two-dimensional photoluminescence data allowed us to differentiate and quantify surface and bulk defects that play a critical yet oft-underappreciated role for photoelectrochemical performance as sites for detrimental carrier recombination. We developed a detailed mechanistic model of how surface and bulk defects were generated as a function of laser processing parameters and obtained key insights on how these defects affected photocurrent production. The controlled healing of defects by pulsed-laser processing may be useful in the design of solar fuels materials.
Lau, M., Reichenberger, S., Haxhiaj, I., Barcikowski, S., Müller, A.M.: Mechanism of Laser-Induced Bulk and Surface Defect Generation in ZnO and TiO2 Nanoparticles: Effect on Photoelectrochemical Performance, ACS Applied Energy Materials 2018, 1 (10), 5366-5385.
Publication alertNew catalyst with dual function
Scientists at Ruhr-University Bochum developed a new economical catalysts for a more sustainable plastics production.
> more about: Press Release Ruhr-University Bochum, 24.07.2018
Barwe, S., Weidner, J., Cychy, S., Morales, D.M., Dieckhöfer, S., Hiltrop, D., Masa, J., Muhler, M., Schuhmann, W.: Electrocatalytic 5-(hydroxymethyl)furfural oxidation using high surface area nickel boride, Angewandte Chemie International Edition 2018, DOI: 10.1002/anie.201806298.
Prof. Dr. Kristina Tschulik honored for her research Hellmuth Fischer Medal
DECHEMA awarded the Hellmuth Fischer Medal to Prof. Dr. Kristina Tschulik, Ruhr-University Bochum, for her fundamental research of electrochemical processes on nanoparticles.
> more about: Press Release Ruhr-University Bochum, 15.06.2018
Heterogeneous Oxidation Catalysis in the Liquid PhaseNew Collaborative Research Centre / Transregio
The new research network, funded by the DFG (German Research Foundation), started its work in July 2018 and will combine catalysis research and nanotechnology. The University of Duisburg-Essen, the Ruhr University Bochum, the MPI für Kohlenforschung, the MPI CEC and the Fritz Haber Institute will work together to accumulate fundamental knowledge and "achieve great things together" (Prof. Dr. Malte Behrens, spokesperson of CRC/TRR 247).
> More detailed information can be found in the press releases:
Press Release DFG, No. 17, 18.05.2018
Press Release University of Duisburg-Essen, 18.05.2018
Press Release Ruhr-University Bochum, 18.05.2018
Press Release MPI CEC, 24.05.2018
Press Release MPI für Kohlenforschung, 03.07.2018
Press Release University of Duisburg-Essen, 28.03.2017