Browsing by Subject "Prussian blue"
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Item Open Access A complementary electrochromic device with highly improved performance based on brick-like hydrated tungsten trioxide film(American Scientific Publishers, 2012) Jiao, Z.; Wang, J.; Ke, L.; Sun, X. W.; Demir, Hilmi VolkanUniform and well adhesive nanostructured hydrated tungsten trioxide (3WO 3•H 2O) films were grown on fluorine doped tin oxide (FTO) substrate via a facile and template-free crystal-seed-assisted hydrothermal method by addition of ammonium sulfate ((NH 4) 2SO 4) and hydrogen peroxide (H 2O 2). X-ray diffraction (XRD) studies indicated that the films are of orthorhombic structure. Scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) analysis showed that the film was composed of brick-like nanostructures with a preferred growing direction along (002). The influence of seed layer, (NH 4) 2SO 4 and H 2O 2 on the products were also studied. The film showed good cyclic stability, comparable switching speed and coloration efficiency (30.1 cm 2 C -1). A complementary electrochromic device based on the film and Prussian blue depicted highly improved color contrast, coloration/bleaching response (1.8 and 3.7 s respectively) and coloration efficiency (164.6 cm 2 C -1).Item Embargo Continuous conducting architecture developed by supporting Prussian blue analogue on metal-organic framework derived carbon-doped manganese- oxide nanorods for high-performance sodium-ion batteries(Elsevier BV, 2023-07-03) Ullah, Irfan; Saeed, Roheen; Inayat, Abid; Zubair, Muhammad; Wu, Xianyong; Duran, Hatice; Haider, Ali; Pope, Michael A.; Hussain, IrshadPrussian blue analogues (PBA) are regarded as promising cathode materials for sodium-ion batteries (SIBs) owing to their open framework with large interstitial sites to accommodate Na+ ions. However, PBA suffer from low electronic conductivity and mechanical instability, which may be improved by their structural modification leading to enhanced kinetics. In this regard, we report an in-situ integration of ultra-small PBA cubes into three-dimensional metal organic framework (MOF) derived carbon-doped manganese oxide nanorods (C-Mn2O3), which form a continuous conductive architecture with intimate PBA/C-Mn2O3 contact. The C-Mn2O3 nanorods provide nucleation sites for the growth of PBA cubes and further act as the electronic pathway to improve electrode reaction kinetics. This hierarchical configuration effectively buffers the lattice expansion, which improve the structural stability of NiCoPBA. Consequently, the composite exhibits promising performance in aqueous Na+ batteries. Specifically, it delivers a high capacity of 97 mAh/g within a narrow potential window of and retained 82% capacity for 1000 cycles in aqueous electrolyte. It shows even higher capacity of 136 mAh/g and similar capacity retention (76% after 1000 cycles) in non-aqueous electrolytes. The promising performance of developed materials demonstrates the significant impact decreasing the size of PBA cubes has on the capacity by reducing the diffusion pathways and thus facilitating intercalation/deintercalation within the cubes. This study offers new insights of exploiting redox-active substrates to modify and stabilize PBA materials for energy storage applications.Item Open Access Corrigendum: Building an iron chromophore incorporating prussian blue analogue for photoelectrochemical water oxidation(Wiley-VCH Verlag GmbH & Co. KGaA, 2021-09-20) Ghobadi, T. Gamze Ulusoy; Ghobadi, Amir; Demirtaş, Merve; Büyüktemiz, M.; Kübra N., Özvural; Yıldız, E. A.; Erdem, E.; Yağlıgül, H. G.; Durgun, Engin; Dede, Y.; Özbay, Ekmel; Karadaş, FerdiThe replacement of traditional ruthenium-based photosensitizers with low-cost and abundant iron analogs is a key step for the advancement of scalable and sustainable dye-sensitized water splitting cells. In this proof-of-concept study, a pyridinium ligand coordinated pentacyanoferrate(II) chromophore is used to construct a cyanide-based CoFe extended bulk framework, in which the iron photosensitizer units are connected to cobalt water oxidation catalytic sites through cyanide linkers. The iron-sensitized photoanode exhibits exceptional stability for at least 5 h at pH 7 and features its photosensitizing ability with an incident photon-to-current conversion capacity up to 500 nm with nanosecond scale excited state lifetime. Ultrafast transient absorption and computational studies reveal that iron and cobalt sites mutually support each other for charge separation via short bridging cyanide groups and for injection to the semiconductor in our proof-of-concept photoelectrochemical device. The reorganization of the excited states due to the mixing of electronic states of metal-based orbitals subsequently tailor the electron transfer cascade during the photoelectrochemical process. This breakthrough in chromophore-catalyst assemblies will spark interest in dye-sensitization with robust bulk systems for photoconversion applications.Item Open Access A cyanide-based coordination polymer for hydrogen evolution electrocatalysis(Springer New York LLC, 2018) Alsaç, Elif Pınar; Ülker, E.; Nune, Satya Vijaya Kumar; Karadaş, FerdiAbstract: Research on H2 production has recently been directed to the development of cost-efficient and robust heterogeneous catalysts for hydrogen evolution reaction (HER). Given the promising catalytic activities of several cobalt-based systems and the robustness of Prussian blue analogues in harsh catalytic processes including water oxidation, a Co-Co Prussian blue analogue was investigated as a HER catalyst for the first time. Co-Co Prussian Blue modified fluorine doped tin oxide (FTO) electrode demonstrated a significant HER activity with an onset overpotential of 257 mV, a Tafel slope of 80 mV dec−1, and a turnover frequency of 0.090 s−1 at an overpotential of 250 mV. Comparative XPS, Infrared, and XRD studies performed on pristine and post-catalytic electrodes confirm the stability of the catalyst.Item Open Access A fast-switching light-writable and electric-erasable negative photoelectrochromic cell based on Prussian blue films(Elsevier, 2011) Jiao, Z.; Song, J. L.; Sun, X. W.; Liu, X. W.; Wang, J. M.; Ke, L.; Demir, Hilmi VolkanWe report a fast-switching negative photoelectrochromic cell composed of a dye-sensitized nanocrystalline TiO2 electrode and Prussian blue counter electrode sandwiching a LiI electrolyte. The cell can be bleached under illumination with shorted TiO2 and Prussian blue electrodes, and re-colored by applying an appropriate external voltage. The photo-bleaching and electric-coloring processes are fast and reversible. A maximum absorbance modulation of 0.44 recorded at 700 nm is obtained between bleached and colored states for the cell when the PB film's thickness is 452 nm. Illuminated under different levels of light intensity or durations of time, the shorted cell shows adjustable optical absorption from 470 to 840 nm. The in-situ transmittance response depicts that the photo-bleaching response is 6.2 s for 70% transmittance change under 100 mW/cm(2) illumination in short circuit configuration, and the re-coloration time is about 600 ms under 2 V bias recorded at 780 nm, with an electrochromic coloration efficiency of 103.4 cm(2)/C. The cell shows a good reversible stability and can be potentially applied in erasable displays.Item Open Access Hybrid CuFe-CoFe prussian blue catalysts on BiVO4for enhanced charge separation and injection for photoelectrochemical water oxidation(American Chemical Society, 2022-12-26) Usman, E.; Vishlaghi, B.; Akbari, Sina Sadigh; Karadaş, F.; Kaya, S.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).Item Open Access Investigation of the ideal composition of metal hexacyanocobaltates with high water oxidation catalytic activity(TÜBİTAK, 2019) Karadaş, FerdiThe electrocatalytic activities of Prussian blue analogues (PBAs) have recently received much attention due to their robustness and efficiency. Considering that PBAs with hexacyanocobaltate building block stand forward among other PBAs, a systematic study on a family of metal hexacyanocobaltates is presented in this study. Metal hexacyanocobaltates (M = Co, Mn, Ni, and Fe) were prepared, characterized, and electrochemical studies were performed. A series of mixed-metal cobalt-iron hexacyanocobaltates has also been studied to determine the ideal composition of a metal hexacyanocobaltate for electrocatalytic water oxidation process. The overall study clearly indicates that cobalt hexacyanocobaltate exhibits the highest electrocatalytic activity among all.Item Open Access A Noble-Metal-Free Heterogeneous Photosensitizer-Relay Catalyst Triad That Catalyzes Water Oxidation under Visible Light(Wiley-VCH Verlag, 2018) Ulusoy-Ghobadi, Türkan Gamze; Yıldız, E. A.; Büyüktemiz, M.; Akbari, S. Sadigh; Topkaya, D.; İşçi, Ü.; Dede, Y.; Yağlioğlu, H. G.; Karadaş, FerdiAn entirely earth-abundant chromophore-relay water oxidation catalyst triad system, which is robust and efficient at neutral pH, is presented. The synthesis involves the coordination of a porphyrin derivative to a bridging Fe(CN)5 group, which is then reacted with Co ions to prepare a covalently linked chromophore-Prussian blue analogue assembly. Light-driven water oxidation studies in the presence of an electron scavenger indicate that the triad is active and it maintains a steady activity for at least three hours. Transient absorption experiments and computational studies reveal that the Fe(CN)5 group is more than a linker as it takes part in electron-transfer and co-operates with porphyrin in the charge separation process.Item Open Access Precious metal‐free photocatalytic water oxidation by a layered double hydroxide‐Prussian blue analogue hybrid assembly(Wiley-VCH Verlag, 2020-11) Akbari, Sina Sadigh; Karadaş, FerdiThe development of earth‐abundant photocatalytic assemblies has been one of the bottlenecks for the advancement of scalable water splitting cells. In this study, a ZnCr layered double hydroxide and a CoFe Prussian blue analogue are combined to afford an earth‐abundant photocatalytic assembly involving a visible light‐absorbing semiconductor (SC) and a water oxidation catalyst (WOC). Compared to bare ZnCr‐LDH, the SC‐WOC hybrid assembly exhibits a threefold enhancement in photocatalytic activity, which is maintained for 6 h under photocatalytic conditions at pH 7. The band energy diagram was extracted from optical and electrochemical studies to elucidate the origin of the enhanced photocatalytic performance. This study marks a straightforward pathway to develop low‐cost and precious metal‐free assemblies for visible light‐driven water oxidation.Item Open Access Pushing the limits in photosensitizer-catalyst interaction via a short cyanide bridge for water oxidation(Cell Press, 2021-02-24) Ghobadi, Türkan Gamze Ulusoy; Ghobadi, Amir; Demirtaş, M.; Phul, Ruby; Yıldız, E. A.; Yağlıoğlu, H. G.; Durgun, Engin; Özbay, Ekmel; Karadaş, FerdiThe realization of high-performance, precious-metal-free, stable, and robust photoanodes for water oxidation is one of the bottlenecks for dye-sensitized water splitting. Herein, we integrate an organic photosensitizer, which absorbs visible light above 500 nm, with a Prussian blue (PB) network to sensitize a visible-light-absorbing semiconductor, WO3. Through comprehensive steady-state and ultrafast transient absorption studies, we show that the coupling of a photosensitizer to a catalyst through a short cyanide bridging group in a PB structure generates appropriate energy levels for an efficient charge transfer from the photosensitizer to the visible-light-absorbing semiconductor. The photoanode retains its structural integrity and high photoelectrochemical activity for at least 2 h of solar irradiation under mildly acidic conditions (pH 3), which reaches around 1.30 mA/cm2 at 1.23 VRHE. This work provides a simple recipe with a toolbox that can be extended to a variety of organic photosensitizers and semiconductors.Item Open Access A robust, precious‐metal‐free dye‐sensitized photoanode for water oxidation: A nanosecond‐long excited‐state lifetime through a Prussian blue analogue(Wiley-VCH Verlag, 2020-02) Ulusoy-Ghobadi, T. Gamze; Ghobadi, Amir; Büyüktemiz, M.; Akhüseyin Yıldız, E.; Yıldız, D. B.; Yağlıoğlu, H. G.; Dede, Y.; Özbay, EkmelHerein, we establish a simple synthetic strategy affording a heterogeneous, precious metal‐free, dye‐sensitized photoelectrode for water oxidation, which incorporates a Prussian blue (PB) structure for the sensitization of TiO2 and water oxidation catalysis. Our approach involves the use of a Fe(CN)5 bridging group not only as a cyanide precursor for the formation of a PB‐type structure but also as an electron shuttle between an organic chromophore and the catalytic center. The resulting hetero‐functional PB‐modified TiO2 electrode demonstrates a low‐cost and easy‐to‐construct photoanode, which exhibits favorable electron transfers with a remarkable excited state lifetime on the order of nanoseconds and an extended light absorption capacity of up to 500 nm. Our approach paves the way for a new family of precious metal‐free robust dye‐sensitized photoelectrodes for water oxidation, in which a variety of common organic chromophores can be employed in conjunction with CoFe PB structures.Item Open Access Strong light–matter interactions in Au plasmonic nanoantennas coupled with Prussian blue catalyst on BiVO4 for photoelectrochemical water splitting(Wiley-VCH Verlag, 2020) Ulusoy-Ghobadi, Türkan Gamze; Ghobadi, Amir; Soydan, Mahmut Can; Vishlaghi, M. B.; Kaya, S.; Karadaş, Ferdi; Özbay, EkmelA 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.