Wyniki wyszukiwania - BazTech

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Graphene hydrogels with embedded metal nanoparticles as efficient catalysts in 4-nitrophenol reduction and methylene blue decolorization

Żelechowska K., Kondratowicz I., Gazda M.

Polish Journal of Chemical Technology

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2016

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Vol. 18, nr 4

47--55

EN

Synthesis and characterization of the graphene hydrogels with three different metallic nanoparticles, that is Au, Ag and Cu, respectively is presented. Synthesized in a one-pot approach graphene hydrogels with embedded metallic nanoparticles were tested as heterogeneous catalysts in a model reaction of 4-nitrophenol reduction. The highest activity was obtained for graphene hydrogel with Cu nanoparticles and additional reaction of methylene blued degradation was evaluated using this system. The obtained outstanding catalytic activity arises from the synergistic effect of graphene and metallic nanoparticles. The hydrogel form of the catalyst benefits in the easiness in separation from the reaction mixture (for example using tweezers) and reusability.

2

Synthesis and modification of reduced graphene oxide aerogels for biofuel cell applications

Kondratowicz I., Żelechowska K., Majdecka D., Bilewicz R.

Materials Science Poland

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2015

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Vol. 33, No. 2

292--300

EN

We have carried out the preparation of reduced graphene oxide aerogels using eco-friendly method that is based on the Hummers method of graphite oxidation without the use of NaNO3 that produces toxic gases. To obtain a porous 3D structure of reduced graphene oxide, we performed the hydrothermal reduction at elevated temperature. We also prepared the rGO aerogel/CNT composite using multiwalled carbon nanotubes as linkers. The rGO aerogels are promising materials as they possess good electrical conductivity (up to 100 S/m) and high surface area and porous structure (similar to 500 m(2)/g). The main goal was to obtain the material for electrodes in enzymatic biofuel cells. Thus, the proper modification was performed using free radical functionalization. It was shown that in order to synthesize rGO aerogels modified with anthracene, the proper order of reactions needs to be provided. The morphology of anthracene modified electrodes was analyzed using scanning electron microscopy, which confirmed their porous structure with non-uniform pore size distribution that ranged between few nanometers to microns. Data obtained by Raman spectroscopy confirmed the successful oxidation and reduction of analyzed materials. UV-Vis spectra revealed the presence of anthracene moieties in examined materials. We also recorded preliminary cyclic voltammograms that confirm an electric conductivity of the obtained structures.

3

Fotometryczny czujnik glukozy oparty na enzymatycznych paskach testowych

Urbanowicz M., Moderhak M., Żelechowska K., Jasiński A., Pomećko R., Bocheńska M.

Elektronika : konstrukcje, technologie, zastosowania

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2015

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Vol. 56, nr 10

77-80

PL

W niniejszej pracy zaprezentowano wyniki alternatywnej metody pomiaru stężenia glukozy. Obecne komercyjne optyczne czujniki glukozy bazują na pomiarze reflektancji. Proponowane rozwiązanie opiera się na pomiarze transmisji promieniowania przez pasek. Prototyp czujnika został zbadany pod kątem zastosowania różnych długości światła, stabilności podczas pomiaru oraz wrażliwości na zmianę temperatury. Zbudowany prototyp czujnika glukozy różni się od tego typu komercyjnych urządzeń. Najważniejszą zmianą jest sposób pomiaru. Przedstawiony tu model glukometru opiera się na pomiarze natężenia światła transmitowanego przez pasek. Dokładne i precyzyjne oznaczanie stężenia glukozy jest szczególnie istotne z punktu widzenia osób cierpiących na cukrzycę, których liczba przekroczyła już 347 milionów ludzi na świecie.

EN

The results for an method of measuring the concentration of glucose are presented in this paper. Currently used commercial optical glucose sensors are based on the reflectance measurement. The proposed in this paper solution is based on the measurement of radiation transmission through the strip. The prototype sensor was tested for the use of different light wavelengths, stability during measurement and sensitivity to the temperature changes. Built prototype glucose sensor is different from the commercial devices. The most important change is the method of measurement. The presented model prototype is based on the measurements of the intensity of light transmitted through the strip. Accurate and precise determination of the glucose concentration is particularly relevant for people with diabetes, the number of which has already exceeded 347 million in the world.

4

Rodzina grafenu

Żelechowska K.

Postępy Fizyki

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2013

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T. 64, z. 2

65--69

PL

Tekst jest próbą sklasyfikowania istniejących materiałów w z rodziny grafenu. W artykule podano definicje dwuwymiarowych materiałów węglowych i określono zasady tworzenia nazw dla nowych pochodnych grafenu, opierając się na wytycznych zaproponowanych przez międzynarodowy zespół redakcyjny czasopisma Carbon.

5

Aryl and N-arylamide carbon nanotubes for electrical coupling of laccase to electrodes in biofuel cells and biobatteries

Żelechowska K., Stolarczyk K., Łyp D., Rogalski J., Roberts K. P., Bilewicz R., Biernat J. F.

Biocybernetics and Biomedical Engineering

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2013

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Vol. 33, no. 4

235--245

EN

Single walled carbon nanotubes (SWCNTs) were equipped with aryl residues by chemical reactions. These insoluble materials were used to substitute classical soluble mediators, which help to transfer electrical charge between the conducting electrode and the redox active center of enzyme molecules. The effect of different aryl residues on the efficiency of the catalytic reduction of dioxygen in the presence of laccase was systematically studied using voltammetry and measuring the power output of a biofuel cell.

6

Organic photovoltaics : chosen aspects

Szostak J., Signerski R., Żelechowska K., Godlewski J.

Elektronika : konstrukcje, technologie, zastosowania

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2012

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Vol. 53, nr 6

118-120

EN

There are many types of organic and organic/inorganic (hybrid) photovoltaic devices that possess many beneficial properties over inorganic solar cells. That makes the former suitable for a broad range of applications and hence so much attention is paid to their development. In spite of intensive research carried on this field of science and technology there are still many crucial problems that need to be solved. Extensive knowledge on physical basis of operation of organic and hybrid systems, fast development of nanotechnology, great variety of organic materials and methods of their modification will pave the way for commercial applications of these devices.

7

Nanorurki w służbie fotowoltaiki

Żelechowska K., Wróbel A.

Czysta Energia

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2012

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Nr 3

28-30

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Carbon nanotubes chemically derivatized with redox systems as mediators for biofuel cell applications

Bilewicz R., Nazaruk E., Żelechowska K., Biernat J. F., Stolarczyk K., Roberts K. P., Ginalska G., Rogalski J.

Biocybernetics and Biomedical Engineering

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2011

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Vol. 31, no. 4

17-30

EN

The aim of this study was designing of nanostructured bioelectrodes and assembling them into a biofuel cell with no separating membrane. Carbon nanotubes (CNTs) chemically connected with residues of typical mediators, i.e. ferrocene (Fc) and 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) deposited on glassy carbon electrodes (GCE) were found useful as mediators for the enzyme catalyzed electrode processes. The electrodes were in turn covered with glucose oxidase from Aspergillus niger AM-11 and laccase from Cerrena unicolor C-139, respectively, incorporated in a liquid-crystalline matrix. The nanostructured electrode coating with the cubic phase film containing enzymes acted as the catalytic surface for the enzymatic reactions that is oxidation of glucose at anode and reduction of oxygen at cathode. For the system with mediators anchored to CNTs the catalysis was almost ten times more efficient than on bare GCE electrodes: catalytic current of glucose oxidation was 1 mAcm-2 and oxygen reduction current exceeded 0.6 mAcm-2. The open circuit voltage of the biofuel cell was 0.43 V. Application of the carbon nanotubes increased maximum power output of the constructed biofuel cell to 100 \miWcm-2 without stirring the solution. It is ca. 100 times more efficient than using the same bioelectrodes without nanotubes on the electrode surface.