Research Interests

Colloidal nanoparticles have attracted much attention due to their unique properties and their potential applications. Nevertheless, a comprehensive picture of nanoparticle growth mechanisms does not exist yet, and the influence of synthesis parameters on the final particle size distribution remains unclear. As a consequence, the common approach for the design of synthetic procedures is based on trial and error. In contrast, profound understanding of nanoparticle growth processes can enable a directed design of synthetic procedures for nanoparticles on demand.

The main goal of our group is to identify general principles of nanoparticle growth and the development of theoretical models.

The investigation of nanoparticle growth mechanisms demands appropriate experimental techniques for the time-resolved in-situ characterization of particles. Therefore, we develop and optimize various setups which can provide information about the particle size distribution and concentration as well as about their optical properties. These setups are applied to study a whole range of systems, from metal nanoparticles in water to metal clusters in glass. The knowledge of the growth mechanism often enables the design of synthetic procedures for tailored particles which can be used e.g. for catalytic applications.

Our Team

  • Dr. Jörg Polte

    Junior Research Group Leader

    2012 -| Humboldt-University of Berlin
    2011/12| PostDoc, Technische Universität Berlin
    2011| Ph.D., Federal Institute for Materials
       Research and Testing
    2007| Diploma in Physics,
       Technische Universität Berlin,
       Freie Universität Berlin
    2003/04| University of Copenhagen

    +49 (0) 30 2093-7121


  • Frieder Kettemann

    Ph.D. student

    2013| Diploma in Chemistry,
       Humboldt-University of Berlin
    2009/10| Chinese University of Hong Kong

    +49 (0) 30 2093-7121


  • Steffen Witte

    Ph.D. student

    2014| Diploma in Chemistry,
       Humboldt-University of Berlin
    2010/11| University of Glasgow

    +49 (0) 30 2093-7121


  • Alexander Birnbaum

    Ph.D. student

    2016| M.Sc., Humboldt-Universität zu Berlin
    2013| B.Sc., Humboldt-University of Berlin
    2014| Chinese University of Hong Kong

    +49 (0) 30 2093-7121





Unifying Concepts in the Room Temperature CO Oxidation with Gold Catalysts

F. Kettemann, S. Witte, A. Birnbaum, B. Paul, G. Clavel, N. Pinna, K. Rademann, R. Kraehnert, J. Polte

ACS Catalysis, 2017, 7 pp. 8247-8254.

Nafion-Free Carbon-Supported Electrocatalysts with Superior Hydrogen Evolution Reaction Performance by Soft Templating

D. Bernsmeier, M. Bernicke, E. Ortel, A. Bergmann, A. Lippitz, J. Nissen, R. Schmack, P Strasse, J. Polte, R. Kraehnert

ChemElectroChem. 2017, 4 (1), pp. 221-229.

Soft-templated mesoporous RuPt/C coatings with enhanced activity in the hydro-gen evolution reaction

D. Bernsmeier, M. Bernicke, E. Ortel, R. Schmack, J. Polte, R. Kraehnert

Journal of Catalysis 2017, 355 pp. 110–119.


Nafion-Free Carbon-Supported Electrocatalysts with Superior Hydrogen Evolution Reaction Performance by Soft Templating

D. Bernsmeier, M. Bernicke, E. Ortel, A. Bergmann, A. Lippitz, J. Nissen, R. Schmack, P. Strasser, J. Polte and R. Kraehnert

ChemElectroChem, accepted.

Yolk@Shell Nanoarchitectures with Bimetallic Nanocores–Synthesis and Electrocatalytic Applications

A. Guiet, T. Unmüssig, C. Göbel, U. Vainio, M. Wollgarten, M. Driess, H. Schlaad, J. Polte and A. Fischer

ACS Appl. Mater. Interfaces 2016, 8 (41), pp. 28019–28029.

The missing piece of the mechanism of the Turkevich method: The critical role of citrate protonation

F. Kettemann, A. Birnbaum, S. Witte, M. Wuithschick, N. Pinna, R. Kraehnert, K. Rademann and J. Polte

Chem. Mater. 2016, 28 (11), pp. 4072–4081.


Hydrophobic Nanoreactor Templating: A Supramolecular Approach to Yolk@Shell Materials

A. Guiet, C. Göbel, K. Klingan, M. Lublow, T. Reier, U. Vainio, R. Kraehnert, H. Schlaad, P. Strasser, I. Zaharieva, H. Dau, M. Driess, J. Polte and A. Fischer

Adv. Funct. Mater. 2015, 25 (39), pp. 6228–6240.

Fundamental growth principles of colloidal metal nanoparticles – a new perspective

J. Polte

CrystEngComm 2015, 17, pp. 6809-6830.

Turkevich in New Robes: Key Questions Answered for the Most Common Gold Nanoparticle Synthesis

M. Wuithschick, A. Birnbaum, S. Witte, M. Sztucki, U. Vainio, N. Pinna, K. Rademann, F. Emmerling, R. Kraehnert and J. Polte

ACS Nano 2015, 9 (7), pp. 7052–7071.

Illustrating the formation of metal nanoparticles with a growth concept based on colloidal stability

M. Wuithschick, S. Witte, F. Kettemann, K. Rademann and J. Polte

Phys. Chem. Chem. Phys. 2015, 17, pp. 19895-19900.

Pd/TiO2 coatings with template-controlled mesopore structure as highly active hydrogenation catalyst

E. Ortel, J. Polte, D. Bernsmeier, B. Eckhardt, B. Paul, A. Bergmann, P. Strasser, F. Emmerling and R. Kraehnert

Appl. Catal., A 2015, 493, pp. 25-32.

Reliable palladium nanoparticle syntheses in aqueous solution: the importance of understanding precursor chemistry and growth mechanism

F. Kettemann, M. Wuithschick, G. Caputo, R. Kraehnert, N. Pinna, K. Rademann and J. Polte

CrystEngComm 2015, 17, pp. 1865-1870.


Antireflective Coatings with Adjustable Refractive Index and Porosity Synthesized by Micelle-Templated Deposition of MgF2 Sol Particles

D. Bernsmeier, J. Polte, E. Ortel, T. Krahl, E. Kemnitz and R. Kraehnert

ACS Appl. Mater. Interfaces 2014, 6 (22), pp. 19559–19565.

In-Situ Determination of Colloidal Gold Concentrations with UV-Vis Spectroscopy: Limitations and perspectives

T. Hendel, M. Wuithschick, F. Kettemann, A. Birnbaum, K. Rademann and J. Polte

Anal. Chem. 2014, 86 (22), pp. 11115–11124.

Versatile control over size and spacing of small mesopores in metal oxide films and catalytic coatings via templating with hyperbranched core–multishell polymers

D. Bernsmeier, E. Ortel, J. Polte, B. Eckhardt, S. Nowag, R. Haag and R. Kraehnert

J. Mater. Chem. A 2014, 2, pp. 13075-13082.


Micelle-Templated Oxides and Carbonates of Zinc, Cobalt, and Aluminum and a Generalized Strategy for Their Synthesis

B. Eckhardt, E. Ortel, D. Bernsmeier, J. Polte, P. Strasser, U. Vainio, F. Emmerling and R. Kraehnert

Chem. Mater. 2013, 25 (14), pp. 2749-2758.

A One-Pot Approach to Mesoporous Metal Oxide Ultrathin Film Electrodes Bearing One Metal Nanoparticle per Pore with Enhanced Electrocatalytic Properties

A. Guiet, T. Reier, N. Heidary, D. Felkel, B. Johnson, U. Vainio, H. Schlaad, Y. Aksu, M. Driess, P. Strasser, A. Thomas, J. Polte and A. Fischer

Chem. Mater. 2013, 25 (23), pp. 4645-4652.

Size-Controlled Synthesis of Colloidal Silver Nanoparticles Based on Mechanistic Understanding

M. Wuithschick, B. Paul, R. Bienert, A. Sarfraz, U. Vainio, M. Sztucki, R. Kraehnert, P. Strasser, K. Rademann, F. Emmerling and J. Polte

Chem. Mater. 2013, 25 (23), pp. 4679-4689.


New Triblock Copolymer Templates, PEO-PB-PEO, for the Synthesis of Titania Films with Controlled Mesopore Size, Wall Thickness, and Bimodal Porosity

E. Ortel, A. Fischer, L. Chuenchom, J. Polte, F. Emmerling, S. Smarsly and R. Kraehnert

Small 2012 8 (2), pp. 298-309.

Formation Mechanism of Colloidal Silver Nanoparticles: Analogies and Differences to the Growth of Gold Nanoparticles

J. Polte, X. Tuaev, M. Wuithschick, A. Fischer, A. Thuenemann, K. Rademann, R. Kraehnert and F. Emmerling

ACS Nano 2012 6 (7), pp. 5791-5802.

Supported Mesoporous and Hierarchical Porous Pd/TiO2 Catalytic Coatings with Controlled Particle Size and Pore Structure

E. Ortel, S. Sokolov, C. Zielke, I. Lauermann, S. Selve, K. Weh, B. Paul, J. Polte and R. Kraehnert

Chem. Mater. 2012, 24 (20), pp. 3828-3838.

Formation Mechanism of Silver Nanoparticles Stabilized in Glassy Matrices

A. Simo, J. Polte, N. Pfander, U. Vainio, F. Emmerling and K. Rademann

J. Am. Chem. Soc. 2012, 134 (45), pp. 18824-18833.

Micelle-Templated Mesoporous Films of Magnesium Carbonate and Magnesium Oxide

B. Eckhardt, E. Ortel, J. Polte, D. Bernsmeier, O. Gorke, P. Strasser and R. Kraehnert

Adv. Mat. 2012, 24 (23), pp. 3115-3119.


SERS enhancement of gold nanospheres of defined size

V. Joseph, A. Matschulat, J. Polte, S. Rolf, F. Emmerling and J. Kneipp

J. Raman Spectrosc. 2011, 42 (9), pp. 1736-1742.


SAXS in combination with a free liquid jet for improved time-resolved in situ studies of the nucleation and growth of nanoparticles

J. Polte, R. Erler, A.F. Thuenemann, F. Emmerling and R. Kraehnert

Chem. Commun. 2010, 46 (48), pp. 9209-9211.

Mechanistic insights into seeded growth processes of gold nanoparticles

J. Polte, M. Herder, R. Erler, S. Rolf, A. Fischer, C. Wuerth, A. Thuenemann, K. Kraehnert and F. Emmerling

Nanoscale 2010, 2 (11), pp. 2463-2469.

New insights of the nucleation and growth process of gold nanoparticles via in situ coupling of SAXS and XANES

J. Polte, R. Kraehnert, M. Radtke, U. Reinholz, H. Riesemeier, A. Thunemann and F. Emmerling

J. Phys.: Conf. Ser. 2010, 247, pp. 012051.

Nucleation and Growth of Gold Nanoparticles Studied via in situ Small Angle X-ray Scattering at Millisecond Time Resolution

J. Polte, R. Erler, A. Thuenemann, S. Sokolov, T. Ahner, K. Rademann, F. Emmerling and R. Kraehnert

ACS Nano 2010, 4 (2), pp. 1076-1082.

Mechanism of Gold Nanoparticle Formation in the Classical Citrate Synthesis Method Derived from Coupled In Situ XANES and SAXS Evaluation

J. Polte, T. Ahner, F. Delissen, S. Sokolov, F. Emmerling, A. Thuenemann and R. Kraehnert

J. Am. Chem. Soc. 2010, 132 (4), pp. 1296-1301.

Real-Time Monitoring of Copolymer Stabilized Growing Gold Nanoparticles

J. Polte, F. Emmerling, M. Radtke, U. Reinholz, H. Riesemeier and A. Thuenemann

Langmuir 2010, 26 (8), pp. 5889-5894.


Superparamagnetic Maghemite Nanorods: Analysis by Coupling Field-Flow Fractionation and Small-Angle X-ray Scattering

A.F. Thuenemann, J. Kegel, J. Polte, and F. Emmerling

Anal. Chem 2008, 80 (15), pp. 5905-5911.

Wet-​chemical passivation of atomically flat and structured silicon substrates for solar cell application

H. Angermann, J. Rappich, L. Korte, I. Sieber, E. Conrad, M. Schmidt, K. Huebener, J. Polte and J. Hauschild

Appl. Surf. Sci. 2008, 254 (12), pp. 3615-3625.


Humboldt Universität zu Berlin, Institut für Chemie, Brook-Taylor Str. 2, 12489 Berlin

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