Researcher:
Barzgarvishlaghi, Mahsa

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PhD Student

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Mahsa

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Barzgarvishlaghi

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Barzgarvishlaghi, Mahsa

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2015 - 201922020 - 20228

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Researcher Of Publications: search.filters.isAuthorOfPublication.9588d69b-d815-4ccb-bff3-ef0932c0e017

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    Hybrid cufe-cofe Prussian blue catalysts on BIVO4 for enhanced charge separation and injection for photoelectrochemical water oxidation
    (American Chemical Society (ACS), 2022) Vishlaghi, Mahsa Barzgar; Akbari, Sina Sadigh; Karadas, Ferdi; Department of Chemistry; N/A; N/A; Kaya, Sarp; Usman, Emre; Barzgarvishlaghi, Mahsa; Faculty Member; Master Student; PhD Student; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; 116541; N/A; N/A
    The utilization of cocatalysts on the photoelectrode surface is a feasible strategy to achieve a high photocurrent density in the photoelectrochemical water oxidation process. The catalysts can enhance the activity by improving the reaction kinetics, retarding charge carrier recombination, or accumulating charge carriers. In this work, we have utilized a CuFe-CoFe Prussian blue (PB) catalyst layer on the BiVO4 photoanode surface to enhance its water oxidation activity. The hybrid catalyst, in which the semiprecious cobalt ions are partially substituted with earth-abundant copper ions, exhibits 56% higher photocurrent density than the CoFe PB-modified BiVO4. We show that photogenerated hole accumulation is present in the CuFe PB layer, which results in higher charge extraction from the BiVO4 surface. The CoFe PB layer on top of the CuFe one facilitates the charge transfer due to its catalytic activity toward the oxygen evolution reaction (OER).
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    Strong light–matter interactions in Au plasmonic nanoantennas coupled with Prussian blue catalyst on BiVO4 for photoelectrochemical water splitting
    (Wiley-VCH Verlag, 2020) Ghobadi, T. Gamze Ulusoy; Ghobadi, Amir; Soydan, Mahmut Can; Karadas, Ferdi; Ozbay, Ekmel; N/A; Department of Chemistry; Kaya, Sarp; Barzgarvishlaghi, Mahsa; Faculty Member; PhD Student; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); College of Sciences; Graduate School of Sciences and Engineering; 116541; N/A
    Invited for this month′s cover is the group of Ferdi Karadas and Ekmel Ozbay at Bilkent University. The image proposes a hybrid architecture, in which the semiconductor photoactive host is coupled to a plasmonic particle and a catalyst, to significantly substantiate the photoactivity of the cell.
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    Effect of experimental factors on magnetic properties of nickel nanoparticles produced by chemical reduction method using a statistical design
    (Elsevier Science Sa, 2015) Vaezi, M. R.; Moradi, O. Mohammad; Barzgarvishlaghi, Mahsa; Tabriz, Meisam Farzalipour; PhD Student; Master Student; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A
    Nickel nanoparticles were synthesized by chemical reduction method in the absence of any surface capping agent. The effect of reactants mixing rate and the volume ratio of methanol/ethanol as solvent on the morphology and magnetic properties of nickel nanoparticles were studied by design of experiment using central composite design. X-ray diffraction (XRD) technique and Transmission Electron Microscopy (TEM) were utilized to characterize the synthesized nanoparticles. Size distribution of particles was studied by Dynamic Light Scattering (DLS) technique and magnetic properties of produced nanoparticles were investigated by Vibrating Sample Magnetometer (VSM) apparatus. The results showed that the magnetic properties of nickel nanoparticles were more influenced by volume ratio of methanol/ethanol than the reactants mixing rate. Super-paramagnetic nickel nanoparticles with size range between 20 and 50 nm were achieved when solvent was pure methanol and the reactants mixing rate was kept at 70 ml/h. But addition of more ethanol to precursor solvent leads to the formation of larger particles with broader size distribution and weak ferromagnetic or super-paramagnetic behavior.
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    Modifying the electron-trapping process at the BiVO4 surface states via the TiO2 overlayer for enhanced water oxidation
    (Amer Chemical Soc, 2021) N/A; N/A; N/A; N/A; Department of Chemistry; Usman, Emre; Barzgarvishlaghi, Mahsa; Kahraman, Abdullah; Solati, Navid; Kaya, Sarp; Master Student; PhD Student; PhD Student; Researcher; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; N/A; N/A; 116541
    BiVO4 is one of the most promising photoanode candidates to achieve high-efficiency water splitting. However, overwhelming charge recombination at the interface limits its water oxidation activity. In this study, we show that the water oxidation activity of the BiVO4 photoanode is significantly boosted by the TiO2 overlayer prepared by atomic layer deposition. With a TiO2 overlayer of an optimized thickness, the photocurrent at 1.23 VRHE increased from 0.64 to 1.1 mA-cm(-2) under front illumination corresponding to 72% enhancement. We attribute this substantial improvement to enhanced charge separation and suppression of surface recombination due to surface-state passivation. We provide direct evidence via transient photocurrent measurements that the TiO2 overlayer significantly decreases the photogenerated electron-trapping process at the BiVO4 surface. Electron-trapping passivation leads to enhanced electron photoconductivity, which results in higher photocurrent enhancement under front illumination rather than back illumination. This feature can be particularly useful for wireless tandem devices for water splitting as the higher band gap photoanodes are typically utilized with front illumination in such configurations. Even though the electron-trapping process is eliminated completely at higher TiO2 overlayer thicknesses, the charge-transfer resistance at the surface also increases significantly, resulting in a diminished photocurrent. We demonstrate that the ultrathin TiO2 overlayer can be used to fine tune the surface properties of BiVO4 and may be used for similar purposes for other photoelectrode systems and other photoelectrocatalytic reactions.
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    The fast-track water oxidation channel on BiVO4 opened by nitrogen treatment
    (Amer Chemical Soc, 2020) N/A; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Kahraman, Abdullah; Barzgarvishlaghi, Mahsa; Toker, Işınsu Baylam; Sennaroğlu, Alphan; Kaya, Sarp; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 23851; 116541
    BiVO4 is one of the most promising photoanode materials for water-splitting systems. Nitrogen incorporation into a BiVO4 surface overcomes the known bottleneck in its charge-transfer kinetics into the electrolyte. We explored the role of nitrogen in the surface charge recombination and charge-transfer kinetics by employing transient photocurrent spectroscopy at the time scale of surface recombination and water oxidation kinetics, transient absorption spectroscopy, and X-ray photoelectron spectroscopy. We attributed the activity enhancement mechanism to the accelerated V5+/V4+ redox process, in which incorporated nitrogen suppresses a limiting surface recombination channel by increasing the oxygen vacancies.
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    Increasing charge separation property and water oxidation activity of BiVO 4 photoanodes via a postsynthetic treatment
    (Amer Chemical Soc, 2020) N/A; N/A; Department of Chemistry; Barzgarvishlaghi, Mahsa; Kahraman, Abdullah; Kaya, Sarp; PhD Student; PhD Student; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 116541
    Postsynthetic treatments of BiVO4 photoanodes have recently shed light on better understanding and improving the photoanodes for water splitting. We demonstrate that a mild heat treatment of BiVO4 under O-2 flow at 200 degrees C improves its water oxidation activity. Charge separation and charge injection efficiencies increase along with the decreased charge transfer resistances across the BiVO4/electrolyte interface. The depletion region width and the band bending have shown to increase after annealing, while charge carrier density remains unchanged. Transient photocurrent measurements further confirm the reduced charge carrier recombination as a result of enlarged band bending. The surface states decrease and the fraction of vanadium ions increases in the surface region after the heat treatment. Since the surface of the BiVO4 photoanodes is generally vanadium deficient, it is suggested that such a treatment can improve the BiVO4 photoanodes performance prepared by other methods as well.
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    Scaling-up photocatalytic activity of CdS from nanorods to nanowires for the MB degradation
    (Elsevier, 2021) Rehman, Zia ur; N/A; N/A; N/A; Department of Chemistry; Ullah, Haseeb; Barzgarvishlaghi, Mahsa; Balkan, Timuçin; Kaya, Sarp; Researcher; PhD Student; Other; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; Graduate School of Sciences and Engineering; N/A; College of Sciences; N/A; N/A; N/A; 116541
    The development of a scalable and facile method for the synthesis of visible light driven photocatalytic materials to degrade toxic organic dyes is highly challenging and essential. In this regards, cadmium sulfide (CdS) nanorods and nanowires with controlled aspect ratio, grain size, surface area, and bandgap were synthesized by a simple solvothermal method, and their photocatalytic performances were exploited for the photo-degradation of methylene blue (MB) under simulated solar light. Extensive structural characterizations to identify the origin of the activities were performed. The photocatalytic activity measurements showed that the degradation of MB was 94.41%, 97.24%, 97.88%, and 99.82% for CdS prepared by following four different synthesis routes and increasing trend showed a correlation with the nanostructure morphology changing from nanorod and nanowires with increasing aspect ratio. It has been found that CdS nanowires show more pronounced photocatalytic activity due to the efficient separation of photo-generated electron-hole pairs induced by increased the aspect ratio and higher active surface area.
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    Roles of charge carriers in the excited state dynamics of BiVO4 photoanodes
    (Amer Chemical Soc, 2019) N/A; N/A; N/A; N/A; Department of Physics; Department of Chemistry; Kahraman, Abdullah; Barzgarvishlaghi, Mahsa; Toker, Işınsu Baylam; Sennaroğlu, Alphan; Kaya, Sarp; PhD Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Physics; Department of Chemistry; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; College of Sciences; N/A; N/A; N/A; 23851; 116541
    Photogenerated charge carrier dynamics of BiVO4 have been investigated by ultrafast transient absorption spectroscopy (TAS), and a numerical modeling has been applied to reveal the origins of the dynamical behavior. The numerical model, based on rate equations, presents the possibility of both photogenerated hole and electron absorption dynamics below 500 nm, as opposed to the generally suggested photogenerated hole absorption mechanism. The investigations done in the ultrafast time regime show that the positive transient absorption peak at 470 nm exhibits inverse behavior as compared to the broad-band feature represented at 550 nm under anodic bias, in the presence of a hole scavenger and at increasing excitation pump power. A combination of TAS findings under various conditions with the numerical modeling reveals that both electron and hole absorption are possible in the spectral region above 500 nm whereas electron absorption at the excited state is the dominant process at shorter wavelengths. Moreover, the major changes in transient absorption response take place in the ultrafast time scale, and overall recombination dynamics is a reflection of the ultrafast recombination mechanism.
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    The significance of the local structure of cobalt-based catalysts on the photoelectrochemical water oxidation activity of BiVO4
    (Pergamon-Elsevier Science Ltd, 2021) Harfouche, Messaoud; Ogasawara, Hirohito; N/A; N/A; N/A; N/A; N/A; N/A; N/A; Department of Chemistry; Barzgarvishlaghi, Mahsa; Kahraman, Abdullah; Apaydın, Sinem; Usman, Emre; Aksoy, Dilan; Balkan, Timuçin; Munir, Shamsa; Kaya, Sarp; PhD Student; PhD Student; Master Student; Master Student; PhD Student; Other; Researcher; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A; College of Sciences; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); N/A; N/A; N/A; N/A; N/A; N/A; N/A; 116541
    The local structures of the water oxidation catalysts play an important role in reaction kinetics and the performance of the photoanodes. In this study, we deposited cobalt-based catalysts on nanoporous BiVO4 with controlled thicknesses by atomic layer deposition (ALD). Despite the similar oxidation states of cobalt in all depositions, different water oxidation activities in neutral pH conditions were observed. A dramatic photocurrent raise, lowered kinetic overpotential, and smaller charge transfer resistance across the photoanode/electrolyte interface were achieved when a uniform ultrathin Co(OH)(2) layer was formed on BiVO4. Photocurrent density for water oxidation showed a 95% enhancement at 0.6 V vs. RHE when the catalyst was in the form of Co(OH)(2), while an 80% increase was obtained for CoO. Ideal coordination of Co(OH)(2) on hydroxylated BiVO4 surface assists the charge transfer between the electrolyte and BiVO4 without increasing surface recombination. The results of this study emphasize the importance of controlling the local structure of the catalysts in the performance of the water splitting photoanodes.
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    Strong light-matter interactions in Au plasmonic nanoantennas coupled with Prussian Blue Catalyst on BiVO(4) for photoelectrochemical water splitting
    (Wiley, 2020) Ghobadi, T. G. U.; Ghobadi, A.; Soydan, M. C.; Karadaş, F.; Özbay, E.; N/A; Department of Chemistry; Barzgarvishlaghi, Mahsa; Kaya, Sarp; Faculty Member; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Graduate School of Sciences and Engineering; College of Sciences; N/A; 116541
    A facial and large-scale compatible fabrication route is established, affording a high-performance heterogeneous plasmonic-based photoelectrode for water oxidation that incorporates a CoFe-Prussian blue analog (PBA) structure as the water oxidation catalytic center. For this purpose, an angled deposition of gold (Au) was used to selectively coat the tips of the bismuth vanadate (BiVO4 ) nanostructures, yielding Au-capped BiVO4 (Au-BiVO4 ). The formation of multiple size/dimension Au capping islands provides strong light-matter interactions at nanoscale dimensions. These plasmonic particles not only enhance light absorption in the bulk BiVO4 (through the excitation of Fabry-Perot (FP) modes) but also contribute to photocurrent generation through the injection of sub-band-gap hot electrons. To substantiate the activity of the photoanodes, the interfacial electron dynamics are significantly improved by using a PBA water oxidation catalyst (WOC) resulting in an Au-BiVO4 /PBA assembly. At 1.23 V (vs. RHE), the photocurrent value for a bare BiVO4 photoanode was obtained as 190 μA cm-2 , whereas it was boosted to 295 μA cm-2 and 1800 μA cm-2 for Au-BiVO4 and Au-BiVO4 /PBA, respectively. Our results suggest that this simple and facial synthetic approach paves the way for plasmonic-based solar water splitting, in which a variety of common metals and semiconductors can be employed in conjunction with catalyst designs.