Photoelectrochemistry

Brief research summary:

The Photoelectrochemical group aims at developing a new class of multicomponent hybrid systems (HNS) composed of a central material (CS), most likely metal oxides semiconductors (TiO2, α-Fe2O3, ZnO, WO3, BiVO4, etc.) and carbon based materials with controlled shape and dimensionality (e.g., 1D-nanotubes, 2D-ultrathin films, 3D branched nanoarchitectures, etc.) that will work as highly photocatalytically and electrocatalytically active materials for a broad portfolio of energy and environmental applications including direct splitting of water, photocatalysis, electrocatalysis, dye sensitized solar cells, etc.. The key-approach is represented by the simultaneous and synergistic combination of strategies (nanostructuring, co-catalyst deposition, surface sensitization) that are still very often studied and developed independently. Therefore, the nanostructured CMs are coupled to counterparts with specific functionalities (extended visible light absorption, remarkable efficiency in charge transfer, enhanced carrier mobility) and the effective interaction of the single components will significantly benefit the PEC efficiency of the composite system. The group is very well equipped for a thorough electrochemical, photoelectrochemical, and photocatalytic investigation of the materials and hybrid nanostructures developed.

 

Bullet specifications of the research activities:

Synthesis of central semiconductor (CS) photo-electrodes

  • Low temperature pulse-modulated magnetron sputtering of nanocystalline 2D thin films; their nano-faceting and nano-gradients engineering for the formation of internal junctions; their elemental doping.
  • Preparation of highly ordered and self-organized 1D nanotube (NT) arrays, by the electrochemical anodization of sputtered metal and metal alloy films
  • Preparation of nanorod (NR) arrays by hydrothermal synthetic pathways.
  • Advanced thermo-chemical treatment of these nanostructures (e.g., high pressure hydrogenation and nitridation

Modification of the CMs to address the major drawbacks limiting their catalytic performances

  • Improvement of the charge dynamics: formation of metastable oxides (g., Fe2TiO5); synthesis and anchoring of graphene derivatives; deposition of multi-layered thin metal oxides to promote charge cascade (TiO2/Fe2O3, TiO2/WO3); formation of a tunnel barrier for preferential e or h+ transport; anchoring of advanced co-catalysts with core-shell nanostructures and of MOFs.
  • Sensitization of wide band gap MSs: attachment of tailored carbon quantum dots, plasmonic nanoparticles, inorganic and organic sensitizers, narrower band gap semiconductors, etc.

Advanced physical and PEC characterizations of the most promising HNS

  • Advanced chemical, structural, and morphological characterization of photoanodes.
  • PEC investigations (photocurrents, OCP, transient spectroscopy, OER, HER, etc.), impedance spectroscopy, solar water splitting performance.
  • Theoretical description and models of HNS.

 

Results highlights – Publications:


S. Kment, P. Schmuki, Z. Hubicka, L. Machala, R. Kirchgeorg, N. Liu, L. Wang, K. Lee, J. Olejnicek, M. Cada, I. Gregora, R. Zboril: Photoanodes with Fully Controllable Texture: The Enhanced Water Splitting Efficiency of Thin Hematite Films Exhibiting Solely (110) Crystal Orientation, ACS NANO vol. 9, iss. 7, pp. 7113-7123, 2017.
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S. Kment, Z. Hubicka, J. Krysa, D. Sekora, M. Zlamal, J. Olejnicek, M. Cada, P. Ksirova, Z. Remes, P. Schmuki, E. Schubert, R. Zboril: On the improvement of PEC activity of hematite thin films deposited by high-power pulsed magnetron sputtering method, APPLIED CATALYSIS B: ENVIRONMENTAL vol. 165, pp. 344-350, 2017.
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A. Naldoni, U. Guler, Z. Wang, M. Marelli, F. Malara, X. Meng, L. V. Besteiro, A. O. Govorov, A. V. Kildishev, A. Boltasseva, V. M. Shalaev: Broadband Hot-Electron Collection for Solar Water Splitting with Plasmonic Titanium Nitride, ADVANCED OPTICAL MATERIALS vol. 5, iss. 15, pp. 1601031, 2017.
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A. Naldoni, V. M. Shalaev, M. L. Brongersma: Applying plasmonics to a sustainable future, SCIENCE vol. 356, iss. 6341, pp. 908-909, 2017.
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H. Han, F. Riboni, F. Karlicky, S. Kment, A. Goswami, P. Sudhagar, J. Yoo, L. Wang, O. Tomanec, M. Petr, O. Haderka, C. Terashima, A. Fujishima, P. Schmuki, R. Zboril: α-Fe2O3/TiO23D hierarchical nanostructures for enhanced photoelectrochemical water splitting, NANOSCALE vol. 9, iss. 1, pp. 134-142, 2017.
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K. Jayaramulu, J. Masa, O. Tomanec, D. Peeters, V. Ranc, A. Schneemann, R. Zboril, W. Schuhmann, R. A. Fischer: Nanoporous Nitrogen-Doped Graphene Oxide/Nickel Sulfide Composite Sheets Derived from a Metal-Organic Framework as an Efficient Electrocatalyst for Hydrogen and Oxygen Evolution, ADVANCED FUNCTIONAL MATERIALS, pp. 1700451, 2017.
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S. Kment, F. Riboni, S. Pausova, L. Wang, L. Wang, H. Han, Z. Hubicka, J. Krysa, P. Schmuki, R. Zboril: Photoanodes based on TiO2 and α-Fe2O3 for solar water splitting – superior role of 1D nanoarchitectures and of combined heterostructures, CHEM. SOC. REV. vol. 46, iss. 12, pp. 3716-3769, 2017.
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K. Lee, A. Mazare, P. Schmuki: One-Dimensional Titanium Dioxide Nanomaterials: Nanotubes, CHEMICAL REVIEWS vol. 114, iss. 19, pp. 9385-9454, 2017.
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Classification of the main hybrid nanostructures based on the heterogeneous partner to the base semiconductor.