Journal

J. Mater. Chem. B, 2014, 2, 1307

Authors

M. Mohl, A. Dombovari, E. S. Tuchina, P. O. Petrov, O. A. Bibikova, I. Skovorodkin, A. P. Popov, A.-R. Rautio, A. Sarkar, J.-P. Mikkola, M. Huuhtanen, S. Vainio, R. L. Keiski, A. Prilepsky, A. Kukovecz, Z. Konya, V. V. Tuchin, K. Kordas

Abstract

Further developments of antibacterial coatings based on photocatalytic nanomaterials could be a promising route towards potential environmentally friendly applications in households, public buildings and health care facilities. Hereby we describe a simple chemical approach to synthesize photocatalytic nanomaterial-embedded coatings using gypsum as a binder. Various types of TiO2 nanofiber-based
photocatalytic materials (nitrogen-doped and/or palladium nanoparticle decorated) and their composites with gypsum were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy as well as electron and X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy
(EDX) techniques. These gypsum-based composites can be directly applied as commercially available
paints on indoor walls. Herein we report that surfaces coated with photocatalytic composites exhibit
excellent antimicrobial properties by killing both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) under blue light. In the case of MSSA cells, the
palladium nanoparticle-decorated and nitrogen-doped TiO2 composites demonstrated the highest
antimicrobial activity. For the MRSA strain even pure gypsum samples were proven to be efficient in
eradicating Gram-positive human pathogens. The cytotoxicity of freestanding TiO2 nanofibers was
revealed by analyzing the viability of HeLa cells using MTT and fluorescent cell assays.

Anne-Riikka Leino, Melinda Mohl, Jarmo Kukkola, Paivi Maki-Arvela,Tommi Kokkonen, Andrey Shchukarev, Krisztian Kordas

Abstract

When in a pure form, carbon nanotubes are known to be stable in air up to ∼800 K making them attractive for a large variety of applications. In this work, we report a significant decrease of ignition temperature (in some cases occurring at ∼500 K) and a reduction in the apparent activation energy for oxidation in air as a result of impregnation with nanoparticles (<2 nm) of metal (Pt, Pd, Ni and Co) acetylacetonates or by decoration with corresponding oxides. Surprisingly, defects introduced by partial oxidation of the carbon nanotubes do not in practice have any influence on the enhancement of further oxidation. Reduction temperatures of metal oxides with H₂ were close to those of other carbon supported catalyst materials. However, the carbon nanotubes showed a tendency for low temperature gasification in the presence of hydrogenation catalyst metals (Pt, Pd).

CARBON 57 (2013) 99–107

http://www.sciencedirect.com/science/article/pii/S0008622313000614

Jarmo Kukkola,* Melinda Mohl, Anne-Riikka Leino, Jani Mäklin, Niina Halonen, Andrey Shchukarev, Zoltan Konya, Heli Jantunen, Krisztian Kordas

Abstract

The emerging hydrogen economy has created a demand for the development of improved hydrogen sensors operating at room temperature. In this work, we present hydrogen detectors based on metal decorated WO₃ nanowires that were able to detect 1000 ppm of H₂, even at room temperature (30 °C), with relatively short recovery time and high sensitivity. The nanowires were synthesized by a hydrothermal process and decorated with PdO and PtO_x nanoparticles by decomposition of Pd(acac)₂ and Pt(acac)₂ precursors. The gas responses were tested for H₂, NO, H₂S and CO analyte gases in an air buffer at 150, 200 and 250 °C (H₂ also at 30, 70 and 130 °C).

http://www.sciencedirect.com/science/article/pii/S0925400513006655