Browsing by Author "Karadaş, F."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Bioinspired copper coordination polymer catalysts for oxygen reduction reaction
    (Wiley, 2017) Mishra, R.; Patil, B.; Karadaş, F.; Yılmaz, E.
    Non–noble metal catalysts have recently emerged as promising alternatives to the expensive platinum catalysts for the oxygen reduction reaction (ORR). In this study, a new domain of materials, copper based coordination polymers, has been investigated as promising catalysts for ORR. The study was inspired by copper incorporating biomolecules, which efficiently catalyse the oxygen reduction reaction in nature. Two coordination polymers, [Cu2(μ−AcO)4Po)]n (shortened as[Cu–A]) and [Cu2(μ−BzO)4Po)]n (shortened as[Cu–B]), incorporating one–dimensional chains of Cu(II) paddle wheel units bridged with phosphineoxide ligands were combined with multi−walled carbon nanotubes (MCNTs) to prepare hybrid electrocatalysts for ORR. The electrochemical analysis demonstrates that [Cu–A] catalyses ORR with 3.24 numbers of electrons with Tafel slopes of 122/83 mV dec−1 while it is 2.37 numbers of electrons with Tafel slopes of 131/84 mV dec−1 for [Cu–B]. Rotating disk electrode measurements and evaluation of Tafel slopes reveal that acetate moieties attached to Cu site shift the onset potential of ORR anodically (ca. 40 mV) compared to the one with benzoate bridging groups. The effect of bridging ligands to the stability and activity of catalysts in alkaline media was also evaluated. This study opens a new perspective for the development of non–platinum ORR catalysts.
  • Thumbnail Image
    ItemOpen 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).