Justyna Piwowar

@article{Piwowar2020,

title = {Formic acid catalytic electrooxidation on Pt covered by Au adstructures – role of electronic surface properties},

author = {Justyna Piwowar, Adam Lewera},

url = {https://www.sciencedirect.com/science/article/pii/S0013468620314924},

doi = {10.1016/j.electacta.2020.137099},

issn = {0013-4686},

year  = {2020},

date = {2020-12-01},

journal = {Electrochimica Acta},

volume = {362},

issue = {137099},

abstract = {In numerous reports present in scientific literature it has been shown that addition of gold to platinum enhances the electrocatalytic activity towards formic acid oxidation, a reaction of importance to low temperature direct fuel cells. While various Pt-Au systems exhibit synergistic effect towards formic acid oxidation, there is no consensus, if the enhanced catalytic activity is due to changes in electronic properties of the surface, or due to the geometric effect. One of the possible reason of this situation is the fact that the electronic properties of Pt-Au systems, especially related to valence band, are seldom measured directly, and in lieu of experimental data authors present the results of DFT calculation. To better understand the role of both: electronic and geometric factors, here we present some insight on the experimentally observable electronic and catalytic properties of Pt-Au surface where the changes of electronic properties were minimized by purposefully depositing Au on Pt to form a separate phase. To study the electronic properties we used an unique approach, which allowed us to obtain the valence band spectra of the Pt-Au surfaces, where contribution from bulk was minimized. While the synergy between Pt and Au towards catalytic formic acid electrooxidation was clearly visible, the changes in valence band spectra for Pt-Au systems, observed by us, can be explained as a superposition of properties of pure Pt and Au elements. Thus we conclude that the synergistic effect in formic acid oxidation in Pt-Au systems, where Pt and Au form separate phases, is most probably not due to changes of the electronic properties beyond superposition of properties of pure metals, but rather caused by other factors, such as geometric effect.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Piwowar2020c,

title = {On the absence of a beneficial role of Rh towards CC bond cleavage during low temperature ethanol electrooxidation on PtRh nanoalloys},

author = {Justyna Piwowar, Adam Lewera},

url = {https://www.sciencedirect.com/science/article/pii/S1572665720304574},

doi = {10.1016/j.jelechem.2020.114229},

issn = {1572-6657},

year  = {2020},

date = {2020-10-15},

urldate = {2020-10-15},

journal = {Journal of Electroanalytical Chemistry},

volume = {875},

issue = {114229},

abstract = {Numerous reports in scientific literature claim the increased activity of Rh-containing systems towards C-C bond scission in the electrocatalytic oxidation of ethanol at ambient temperatures. Due to the claimed C-C bond breaking ability, Rh-containing systems are intensively investigated and widely recognized as the most promising candidates for anode materials in ethanol-feed low temperature fuel cells. Contrary to those claims, we determined that the surface-normalized amounts of CO2 produced during ethanol oxidation are comparable on Pt, Rh and PtRh nanoalloys, and smaller than CO2 amounts obtained on exactly the same electrode when a monolayer of adsorbed CO is being oxidized. The whole amount of CO2 detected during ethanol oxidation, regardless of Rh presence or lack of thereof, seems to come exclusively from oxidation of submonolayer of COads produced from ethanol, undergoing dissociative adsorption of ethanol at low electrode potential, and its subsequent oxidation at sufficiently high electrode potential. Our work suggests that Rh-containing alloys are not more active towards C-C bond scission than pure Pt, and on both metals the mechanism of oxidation of ethanol to CO2 roceeds via the submonolayer of COads, which limits the quantity of CO2 produced from ethanol at room temperature to negligible amount. Additionally, based on critical literature analysis we determined that the higher activity of Rh-containing materials towards C-C bond scission claimed in literature, was an over-interpretation of data.},

key = {Ethanol oxidation; Carbon-carbon bond scission; Electrocatalysis; Platinum; Rhodium},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Piwowar2016,

title = {Epitaxial growth and photoluminescence excitation spectroscopy of CdSe quantum dots in (Zn,Cd)Se barrier},

author = {J. Piwowar, W. Pacuski, T. Smoleński, M. Goryca, A. Bogucki, A. Golnik, M. Nawrocki, P. Kossacki, J. Suffczyński},

url = {https://www.sciencedirect.com/science/article/pii/S0022231315303306},

doi = {10.1016/j.jlumin.2015.12.046},

issn = {0022-2313},

year  = {2016},

date = {2016-05-01},

urldate = {2016-05-01},

journal = {Journal of Luminescence},

volume = {173},

pages = {94-98},

abstract = {Design, epitaxial growth, and resonant spectroscopy of CdSe Quantum Dots (QDs) embedded in an innovative (Zn,Cd)Se barrier are presented. The (Zn,Cd)Se barrier enables shifting of QDs energy emission down to 1.87eV, that is below the energy of Mn2+ ions internal transition (2.1eV). This opens a perspective for implementation of epitaxial CdSe QDs doped with several Mn ions as, e.g., the light sources in high quantum yield magnetooptical devices. Polarization resolved Photoluminescence Excitation measurements of individual QDs reveal sharp (Γ<150μeV) maxima and transfer of optical polarization to QD confining charged exciton state with efficiency attaining 26%. The QD doping with single Mn2+ ions is achieved.},

key = {Quantum dot; Exciton; Auger recombination; Photoluminescence excitation; CdSe},

keywords = {},

pubstate = {published},

tppubtype = {article}

}