The first UnOCat summer school will take place from 13^th to 17^th of July, 2020. Please save the date!

All CRC/TRR 247 PhDs are invited to participate.

Further information is available here.

Greetings of the season and our best wishes for a prosperous New Year 2020!

On 5^th of Decemer 2019,  AGEF and SFB/TRR 247 will host a joint workshop on "Interfacial Solvent in Electrochemistry" in Duisburg, at the NETZ building of the University Duisburg-Essen. AGEF is an association of electrochemistry research institutions in North Rhine-Westphalia.

The program can be found here.

> more about: Press Release MPI Kofo, 26.11.2019

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.

On 16^th 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.

Chemists have developed a new method with which they can characterise individual noble-metal-free nanoparticle catalysts. The particles could be a cheap alternative to precious metal catalysts for obtaining hydrogen from water by means of electrolysis.
So far, there are few techniques available to measure the catalytic activity of individual or a few nanoparticles. “The currents that have to be measured are extremely small, and one has to find single or few nanoparticles in order to measure them reproducibly,” explains Prof. Wolfgang Schuhmann. The research team showed that such analyses are also possible with high throughput – namely with scanning electrochemical cell microscopy.

Original publication
Tarnev, T., Aiyappa, H.B., Botz, A., Erichsen, T., Ernst, A., Andronescu, C., Schuhmann, W.: Scanning electrochemical cell microscopy investigation of single ZIF‐derived nanocomposite particles as electrocatalysts for oxygen evolution in alkaline media, Angewandte Chemie International Edition, 2019, 58, 14265-14269, DOI: 10.1002/anie.201908021

> more about: Press Release Ruhr-University Bochum, 04.10.2019

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.

Ready for our second day of our first year workshop for the CRC/TRR 247 heterogeneous oxidation catalysis in the liquid phase. Great scientific discussions yesterday in a collaborative environment. pic.twitter.com/eDtI8iLW09

— Spectroelectrochemstry lab MPI-CEC (@SECLab_MPI_CEC) 27. September 2019

Our annual workshop will take place at the Ruhr-University Bochum on 26^th/27^th of September.

More information can be found here.

The first UnOCat retreat will take place at Kinder- und Jugendcamp Haard e.V., Haardgrenzweg 200, Oer-Erkenschwick and will start on September 2^nd in the afternoon and ends on September 4^th after breakfast.

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

> more about: Introducing ... Dr. Stéphane Kenmoe

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.

Original publication
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

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

Morning! I am Tong Li from Institute for Materials. Today, I will give a taste about what we are working on in my group @TemApt. #TwitterTakeover ^tl pic.twitter.com/SO9kDLAP0u

— Ruhr-Universität (@ruhrunibochum) 6. Juni 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

I am currently investigating a wide range of materials such as high-strength #TitaniumAlloys for #Aerospace applications, and #Catalysts for water splitting. ^tl

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

Thanks to atom probe tomography! Now we can see individual chromium atoms (pink) and nanoprecipitates (green particles) in nickel #superalloys. ^tl pic.twitter.com/C1dCG9TYgz

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

My student is preparing a sample for #AtomProbe tomography. It will take up to five hours. ^tl pic.twitter.com/SznfI2h0ca

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

Discussing future projects with Alfred Ludwig and Janine Pfetzing at our new research building ZGH during coffee break. ^tl #KnowledgeNetworks pic.twitter.com/fh7FMJ9aob

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

Extremely insightful meeting with Kristina @TschulikGroup from @SolvationSci about how to use atom probe tomography in field of #chemistry #knowledgenetworks ^tl pic.twitter.com/AZGdipagoE

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

Kick-off meeting with Ulf-Peter Apfel to see how atom probe tomography can work for industrial catalysts #knowledgenetworks pic.twitter.com/39vuqb3Ucb

— Ruhr-Universität (@ruhrunibochum) 6. Juni 2019

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.

Original publication
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

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.

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 Co_5c³⁺ 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.

Original publication
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.

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'.

> more about: Press Release idw, 03.05.2019
> more about: Press Release Ruhr-University Bochum, 03.05.2019

Original publication
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

Dr. Hamidreza Hajiyani won the poster award at the International Bunsen-Discussion-Meeting "Fundamentals and Applications of (Photo)Electrolysis for Efficient Energy Storage" (01.-05.04.2019, Taormina , Italy) for his contribution "Why Tin-doping enhances the efficiency of Hematite photoanodes for water splitting".

The publication has also been selected as the cover page of Advanced Functional Materials.

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

Our first assembly of the CRC/TRR 247 graduate school UnOCat "Understanding Oxidation Catalysis" took place at the RUB on 7^th 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.

Spray-flame synthesized LaCo_1-xFe_xO₃ 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.

> One of the three winners of the „CENIDE Best Paper Award“ 2019 (Press Release 14.11.2019)

Original publication
Alkan, B., Cychy, S., Varhade, S., Muhler, M., Schulz, C., Schuhmann, W., Wiggers, H., Andronescu, C.: Spray‐Flame‐Synthesized LaCo_1−xFe_xO₃ Perovskite Nanoparticles as Electrocatalysts for Water and Ethanol Oxidation, ChemElectroChem 2019, 6, 1-10.

On 11^th 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.

The scientists report on the synthesis of bimetallic Co_xFe_y alloy nanoparticles encapsulated in an N‐doped graphene shell containing molybdenum carbide (Mo₂C) nanoparticles, which are obtained by the pyrolysis of cobalt ferrite Co_xFe_3‐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 Co_xFe_y 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.

Original publication
Wang, S., Bendt, G., Saddeler, S., Schulz, S.: Synergistic Effects of Mo₂C‐NC@Co_xFe_y Core–Shell Nanoparticles in Electrocatalytic Overall Water Splitting Reaction, Energy Technology 2019, 7, DOI: 10.1002/ente.201801121.

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.

Greetings of the season and our best wishes for a prosperous New Year 2019!

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.

> more about: Press Release idw, 14.12.2018
> more about: Press Release CENIDE, 17.12.2018

In total 74 scientists, including project leaders, but also young researchers, participated in our kick-off meeting in Duisburg on 4^th/5^th of December 2018.

> more about: Press Release CENIDE, 17.12.2018

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.

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.

Original publication
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.

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 Co_xNi_1–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.

Original publication
Hajiyani, H., Pentcheva, R.: Surface Termination and Composition Control of Activity of the Co_xNi_1–xFe₂O₄(001) Surface for Water Oxidation: Insights from DFT+U Calculations, ACS Catalysis 2018, 8 (12), 11773-11782.

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

Original publication
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

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
 

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.

Original publication
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.

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.

Original publication
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.

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

Original publication
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.

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

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