Search

Currently, energy-efficient electrocatalytic oxygen evolution from water involves the use of noble metal oxides. Here, we show that highly p-conducting zinc cobaltite spinel Zn1.2Co1.8O3.5 offers an enhanced electrocatalytic activity for oxygen evolution. We refer to previous studies on sputtered Zn–Co spinels with optimized conductivity for implementation as (p-type) transparent conducting oxides. Based on that, we manufacture off-stoichiometric conducting p-spinel catalytic anodes on tetragonal Ti, Au–Ti and hexagonal Al-doped ZnO carriers and report the evolution of O2 at Tafel slopes between 40.5 and 48 mV dec−1 and at overpotentials between 0.35 and 0.43 V (at 10 mA cm−2). The anodic stability, i.e., 50 h of continuous O2 electrolysis in 1 M KOH, suggests that increasing the conductivity is advantageous for electrolysis, particularly for reducing the ohmic losses and ensuring activity across the entire surface. We conclude by pointing out the merits of improving p-doping in Zn–Co spinels by optimized growth on a tetragonal Ti-carrier and their application as dimension-stable 3d-metal anodes., Zinc cobaltite spinels show enhanced electrocatalytic activity for oxygen evolution. The spinels evolve O2 at Tafel slopes between 40.5 and 48 mV dec−1 and at overpotentials between 0.35 and 0.43 V at 10 mA cm−2. Their stability underlines their utility as 3d-metal anodes.

Microbial electrolysis cells (MECs) consisting of a bioanode and biocathode offer a promising solution for wastewater treatment. These systems can degrade organic substances at the bioanode while converting carbon dioxide (CO2), a major greenhouse gas, to a value-added fuel, methane (CH4) at the biocathode. The bioelectrodes were inoculated with a mixed culture under anaerobic conditions. By applying a constant potential of 0.40 V vs. Ag/AgCl (3 M NaCl), the long-term performance of MECs has been studied by monitoring the removal of chemical oxygen demand (COD) in the anolyte which contained synthetic wastewater and CH4 generation in the cathode chamber. To investigate the effect of electrode modification, poly(neutral red) and chitosan modified carbon felt electrodes were prepared, and applied in MECs. The results revealed that MECs with modified electrodes showed remarkably enhanced overall performance. The average COD removal efficiency, faradaic efficiency towards CO2 reduction to CH4 and CH4 production yield of modified MECs were up to 67%, 55% and 0.14 LCH4/gCOD, respectively.

Material science is one of the decisive tools toward engineering versatile compounds for numerous technological applications. Over the last decades, thiospinels have been attracting great interest because of their unique characteristics and potential utilizations offering innovative and interesting features. The characteristics of these transition metal sulfides play a key role in many different applications and make thiospinels an essential class of material. To the best of our knowledge, this work, for the first time, summarizes broadband studies on thiospinels reported in the literature. The scope of this review covers all synthesis methods applied over, the chemical and physical properties, and the clean energy applications of thiospinels, which have achieved tremendous significance. It underlined and proposed the challenges and future perspectives based on sulfur-based ternary compounds. Moreover, this review draws attention to the current and future research needs of thiospinel materials to improve and broaden their applications and thus commercialization. (C) 2021 Elsevier Ltd. All rights reserved.

When it is asked, "where can refractory metals be used?," the possible shortest answer is, "where cannot they be used?" The uses of refractory-metal-based compounds in research and industry are too many to be enumerated; nevertheless, some outstanding examples are briefly mentioned here. Essentially, chalcogenide forms of refractory metals are preferred in the fabrication of high-performance structures. Therefore, expanding the current studies that usually focus on tungsten- and molybdenum-based structures to other materials may open new opportunities. Moreover, research on ternary and quaternary structures can also be a keystone in creating high-performance products. The rationale of the present review is to give a brief overview of the recent history of refractory-metal-based chalcogenides (RMCs). Initially, the framework is confined to the general design and approaches for the synthesis of refractory metal chalcogenides. The assay is continued by extending with characteristic features of materials from crystalline properties to thermoelectric attributes and examining device fabrication processes. Taken together, the device fabrication part where RMCs are mainly used is extensively focused upon. Finally, outlook and future perspectives are given on the design and construction of RMCs to enable future inspiration and innovation.

Electrocatalytic CO2-to-CO conversion represents one pathway to upgrade CO2 to a feedstock for both fuels and chemicals (CO, deployed in ensuing Fischer–Tropsch or bioupgrading). It necessitates se...

The development of the non-precious, earth abundant and inexpensive catalysts with high catalytic efficiency for the electrocatalytic hydrogen evolution reaction acts an essential role in sustainable energy conversion and storage. Herein, we report that hydrogen evolution in two-phase systems by an organic soluble electron donor decamethylferrocene (DMFc) has been efficiently catalyzed by Co3O4 and NiO nanofiber catalysts, which are fabricated by the low-cost and simple electrospinning method. The catalytic activities of these metal oxide nanofibers have been examined by two-phase reactions and four-electrode cyclic voltammetry methods at water/1,2 dichloroethane interface. The hydrogen evolution reaction rate of nanofiber catalysts is also compared to the bulk forms of these metal oxide catalysts. The reaction rate is increased 74, 152, 284 and 384 times by using bulk and nanofiber forms of Co3O4 and NiO, respectively, when compared to an uncatalyzed reaction. The higher catalytic activity of the metal oxide nanofibers can be ascribed to the enhanced surface to volume ratio revealed from the fibrous structures. (c) 2018 Elsevier Ltd. All rights reserved.

Herein, we report the synthesis of chalcostibite (CuSbS 2 ) nanocrystals based on hot injection method and the characterization of CuSbS 2 thin films by spin coating technique. The deposited films were subjected to the UV–Vis spectrophotometer, XRD, TEM and SAED for optical, structural, morphological and elemental analysis. XRD pattern showed that CuSbS 2 nanocrystals have chalcostibite structures and SAED diffraction spots supported the XRD results. Different optical parameters like extinction coefficient, refractive index, real and imaginary parts of dielectric constant and surface and volume energy loss functions have been calculated applying single term Sellmeier dispersion relation and Wemple–DiDomenico single oscillator model. The obtained results are discussed in detail. The optical dispersion and dielectric properties of the CuSbS 2 have been determined by the transmittance and reflectance modes in the range of 300–1600 nm. Thus, the CuSbS 2 is transparent up to 40–45% in the visible range. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess direct bandgap of 1.86 eV. The calculated refractive index of thin film varies between 1.76 and 2.11 throughout the spectral region considered. The results presented here permit a better understanding of the properties of the chalcostibite nanocrystals which in turn result in the design of more efficient solar cells.

International Congress on Semiconductor Materials and Devices (ICSMD) -- AUG 17-19, 2017 -- Selcuk Univ, Konya, TURKEY, WOS: 000495858400010, The present study reports, for the first time, a facile synthesis for ternary ZnMn2O4 nanocrystals synthesized by a simple and low cost two-phase method. Those nanocrystals were used on thin film solar cell as active absorber layer. The resulting nanocrystals were characterized by XRD, TEM, AFM-MFM, FTIR and JV characterization techniques to investigate the crystalline behavior, chemical composition, morphology and optical properties. Two phase method allows the successful synthesis of oleic acid (OA) capped ZnMn2O4 nanocrystals with 5-10 nm particle size. After doping of the ZnMn2O4 nanocrystals at different ratios with P3HT:PCBM, an enhancement was observed in the solar cell performances based on thin films. The power conversion efficiency of P3HT:PCBM-ZnMn2O4 thin film solar cell was investigated by J-V characteristic curve and as a result of this study, the highest efficiency was achieved as 3.27% with a doping ratio of 1%. Thus we believe that this work will open a new perspective to the synthesis of ZnMn2O4 materials for applications in the field of energy conversion systems. (C) 2019 Elsevier Ltd. All rights reserved., TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109T881]; Selcuk UniversitySelcuk University [12101017]; Karamanoglu Mehmetbey UniversityKaramanoglu Mehmetbey University [02-YL-15], The authors would like to thank to TUBITAK (The Scientific and Technological Research Council of Turkey) (109T881) for supporting this work as well as Selcuk and Karamanoglu Mehmetbey University for Scientific Research Foundation (12101017 and 02-YL-15, respectively).

Electrochemical conversion of CO2 to alcohols is one of the most challenging methods of conversion and storage of electrical energy in the form of high-energy fuels. The challenge lies in the catalyst design to enable its real-life implementation. Herein, we demonstrate the synthesis and characterization of a cobalt(III) triphenylphosphine corrole complex, which contains three polyethylene glycol residues attached at the meso-phenyl groups. Electron-donation and therefore reduction of the cobalt from cobalt(III) to cobalt(I) is accompanied by removal of the axial ligand, thus resulting in a square-planar cobalt(I) complex. The cobalt(I) as an electron-rich supernucleophilic d8-configurated metal centre, where two electrons occupy and fill up the antibonding dz2 orbital. This orbital possesses high affinity towards electrophiles, allowing for such electronically configurated metals reactions with carbon dioxide. Herein, we report the potential dependent heterogeneous electroreduction of CO2 to ethanol or methanol of an immobilized cobalt A3-corrole catalyst system. In moderately acidic aqueous medium (pH = 6.0), the cobalt corrole modified carbon paper electrode exhibits a Faradaic Efficiency (FE%) of 48 % towards ethanol production., Electrochemical conversion of carbon dioxide to ethanol is one of the most challenging energy conversion reactions. Here the authors show selective electroreduction of carbon dioxide to ethanol by using a functionalized cobalt A3-corrole catalyst immobilized on a carbon paper electrode.

Microbial electrosynthetic cells containing Methylobacterium extorquens were studied for the reduction of CO

Electrocatalysis of hydrogen and oxygen evolution is an essential route in performing renewable and sustainable energy alternatives. Although hydrogen technologies are largely advanced, the oxygen electrochemistry is mainly limited due to the complexity in seeking suitable and stable electrocatalysts, in unifying electrolytic conditions and hence sluggish reaction kinetics. Herein, we demonstrate the electrocatalytic activity of the nanofibrous cobalt oxide in alkaline oxygen evolution reaction with a generous operation lifetime of 120 hours. The unique and facile preparation pathway of fibers by electrospinning allows enlarged electrode networking and nanofibrous interaction thus leading to extended catalytically active surface area, imperative for well-performing electrolysis. Operating at low overpotential of 293 mV at a current density of 10 mA cm- 2, as well as low Tafel slope of 60.5 mVdec-1 in 1M KOH prove the efficient utilization of nanofibrous Co3O4 electrocatalyst towards oxygen evolution with an excellent long-term stability over 100 hours.[1] [1] A.A., Long-Lasting Electrospun Co3O4 Nanofibers for Electrocatalytic Oxygen Evolution Reaction, ChemistrySelect 2020, 5, 748, doi.org/10.1002/slct.20.

The current study reports the application of chalcopyrite semiconductor CuInS2 (CIS) nanofibers for the reduction of CO2 to CO with a remarkable Faradaic efficiency of 77 ± 4%. Initially the synthesis of CuInS2 nanofibers was carried out by adaptable electrospinning technique. To reduce the imperfection in the crystalline fiber, polyacrylonitrile (PAN) was selected as template polymer. Afterward, the desired chemical structure of nanofibers was achieved through sulfurization process. Making continuous CuInS2 nanofibers on the cathode surface by the electrospinning method brings the advantages of being economical, environmentally safe, and versatile. The obtained nanofibers of well investigated size and diameter according to the SEM (scanning electron microscope) were used in electrochemical studies. An improvement of Faradaic efficiency was achieved with the catalytic active CuInS2 in nanofibrous structure as compared to the solution processed CuInS2. This underlines the important effect of the electrode ...

The undertaken study describes synthesis of urchin-like Cobalt nanostructures (Co NSs) in aqueous solution using gallic acid as both reductant and protecting agent for the catalytic degradation of 4-methyle-2-nitroaniline. UV-Visible (UV-Vis) spectroscopy was used as a primary tool to elaborately study and optimizes the necessary experimental condition for the developed synthetic protocol Fourier transform infrared (FTIR) spectroscopy showed the interaction between gallic acid and the surface of Co NSs via -OH linkages although Scanning electron microscopy (SEM) confirmed the formation of urchin shaped nanostructures with diameter in the range of 80-110 nm and length of tentacles between 1.0 - 1.8 µm. The as-synthesized Co NSs proved to be excellent heterogeneous catalyst for the 100 % reductive degradation of 4-methyle-2-nitroaniline in just 60 sec in presence of reductant (NaBH4) with reaction rate calculated to follow pseudo first order kinetic and rate constant of 0.055s -1 . Furthermore, Co NSs, showed excellent recyclability and were reused four times for the degradation of 4-methyle-2- nitroaniline with efficiency that displayed negligible catalytic poisoning. Copyright © 2016 VBRI Press.

１． Intention Concentration of carbon dioxide (CO2) in the atmosphere has steadily increased since industrial revolution. Despite the recent significant cost reduction of renewable electricity by solar and wind, their intermittency hinders the total shift to renewable energy. It is urgently needed to develop technologies for fast conversion of electrical energy into storable chemical energy by electrolysis, e.g., by water splitting and CO2 reduction. Stable and high-performance electrocatalysts are essential but must be developed without depending on precious metals for the real use and sustainability of the technology. Recently, we have demonstrated high and stable electrocatalytic properties of conductive organic polymers, such as polydopamine (PDA) and polyguanine (PGA) for hydrogen evolution reaction (HER) and CO2 reduction reaction (CO2RR)1,2). Hydrogen bonding N and O atoms introduced to these polymers are expected to stabilize the reaction intermediates for their high catalytic activities. In this study, a phenazine dye, neutral red (NR) was employed as the monomer to obtain a metal-free catalyst. NR bears many amino functions to make it electropolymerizable just like poly-aniline (electropolymerization deposition, to be called EPD). Also, oxidative chemical vapor deposition (oCVD) was employed to obtain PNR. Synthesis, characterization and comparison of the catalytic activities of PNR by EPD and oCVD are discussed. ２． Experiment EPD of PNR onto carbon felt (CF) was carried out by cycling potential between -1 and +1 V vs. Ag/AgCl for 100 cycles in an aqueous solution containing 0.2 mmol/L NR and 0.5 mol/L KNO3 (pH 5) at 50 mV/s. oCVD of PNR was performed in a three-zone quartz tube furnace under N2 flow, while setting the temperature for NR, sulfuric acid and CF at 375, 220 and 100ºC, respectively, for 240 min. PNR-modified as well as bare CF electrodes were measured under N2 and CO2 in a 1 M KNO3 (pH 7) for their catalytic activities for HER and CO2RR. ３． Result While bare carbon felt (CF) electrode does not show any catalytic activity towards CO2RR, showing about -3 mA cm-2 current at –1 V vs. Ag/AgCl, supposedly dominated by that for HER, the PNR coated CFs show enhanced current (Fig. 1a). That by EPD gives about -5 and -6 mA under N2 and CO2, respectively, indicating its moderate catalytic activity for HER and CO2RR. PNR prepared by oCVD, on the other hand, gives -6 and -12 mA, to demonstrate its superior activity, especially for CO2RR. Chronoamperogram measured during long term electrolysis for 17 h at the oCVD PNR electrode indicates reasonable stability of the catalysis (Fig 1b). These results already nicely confirm catalytic activity of PNR for its conductivity and hydrogen-bonding ability. H. Coskun et al., Sci. Adv. 3, e1700686 (2017). H. Coskun et al., Adv. Mater. Interf. 10, 1901364 (2019). Figure 1

The most active and efficient catalysts for the electrochemical hydrogen evolution reaction (HER) rely on platinum, a fact that increases the cost of producing hydrogen and thereby limits the widespread adoption of this fuel. Here, a metal-free organic electrocatalyst that mimics the platinum surface by implementing a high work function and incorporating hydrogen-affine hydrogen bonds is introduced. These motifs, inspired from enzymology, are deployed here as selective reaction centres. It is shown that the keto-amine hydrogen-bond motif enhances the rate-determining step in proton reduction to molecular hydrogen. The keto-amine-functionalized polymers reported herein evolve hydrogen at an overpotential of 190 mV. They share certain key properties with platinum: a similar work function and excellent electrochemical stability and chemical robustness. These properties allow the demonstration of one week of continuous HER operation without notable degradation nor delamination from the carrier electrode. Scaled continuous-flow electrolysis is reported and 1 L net molecular hydrogen is produced within less than 9 h using 2.3 mg of polymer electrocatalyst.

Two-dimensional transition metal dichalcogenides (TMDCs) are the most efficient and selective electrocatalysts for the heterogenous CO2 reduction to CO, along with MoS2, WS2, and their diselenides.[1, 2] Here we show CO electrosynthesis using atomic layer deposited TiS2 with a maximum Faraday yield of 64 % at an overpotential of less than 0.4V at 5 mA cm-2. We provide mechanistic insights on the electrosynthesis of C=O by the insitu ATR-FTIR spectroelectrochemistry. Operando studies reveal that the reason of high CO selectivity is due to the CO2 binding on active disulfide planes. Paired with mild synthesis protocol, reasonable stability and low-cost production, semi-metallic TiS2 promises satisfying applicability in CO2 electroreduction and utilization technology. [1] P. Abbasi, M. Asadi, C. Liu, S. Sharifi-Asl, B. Sayahpour, A. Behranginia, P. Zapol, R. Shahbazian-Yassar, L.A. Curtiss, A. Salehi-Khojin, Tailoring the edge structure of molybdenum disulfide toward electrocatalytic reduction of carbon dioxide, ACS nano, 11 (2016) 453-460. [2] M. Asadi, K. Kim, C. Liu, A.V. Addepalli, P. Abbasi, P. Yasaei, P. Phillips, A. Behranginia, J.M. Cerrato, R. Haasch, P. Zapol, B. Kumar, R.F. Klie, J. Abiade, L.A. Curtiss, A. Salehi-Khojin, Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid, Science, 353 (2016) 467-470.

The most active and efficient catalysts for the electrochemical hydrogen evolution reaction rely on noble metals, a fact that increases the cost of producing hydrogen and thereby limits the widespread adoption of this fuel. Here we present metal-free polydopamine and polyguanine as selective organic hydrogen electrocatalysts1–3. The conducting functional polymers incorporate selective hydrogen-affine hydrogen bonds that possess a similar hydrogen binding energies and work function as e.g. platinum. We report the synthesis of hydrogen-selective electrocatalytic polyguanine and polydopamine and demonstrate the enhancement of the rate-determining step in the proton reduction. We further present mechanistic spectral IR-operando studies on the catalytic hydrogen bonded motifs as well as the continuous electrolysis to molecular hydrogen using polyguanine and polydopamine electrodes for several 100 hours without notable degradation. (1) Coskun, H.; Aljabour, A.; Schöfberger, W.; Hinterreiter, A.; Stifter, D.; Sariciftci, N. S.; Stadler, P. Cofunction of Protons as Dopant and Reactant Activate the Electrocatalytic Hydrogen Evolution in Emeraldine‐Polyguanine. Adv. Mater. Interfaces 2019, 1901364 DOI: 10.1002/admi.201901364. (2) Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S. Chemical Vapor Deposition - Based Synthesis of Conductive Polydopamine Thin-Films. Thin Solid Films 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063. (3) Coskun, H.; Aljabour, A.; Luna, P. De; Sun, H.; Nishiumi, N.; Yoshida, T.; Koller, G.; Ramsey, M. G.; Greunz, T.; Stifter, D.; Hassel, A. W.; Sariciftci, N. S.; Sargent, E. H.; Stadler, P. Hydrogen-Bonded Polymers Mimic Noble Metal Electrocatalysts. Adv. Mater., submitted.

Electrocatalytic hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CO2RR) are the key reactions for conversion of renewable electricity into storable chemical energies. It is crucially important to develop active and stable electrocatalysts without relying on rare metal elements for sustainable energy systems. Recently, some metal-free conductive organic polymers such as polydopamine (PDA) and poly guanine (PGA) synthesized by oxidative chemical vapor deposition (oCVD) have been found to exhibit high catalytic activity and durability for HER and CO2RR1,2. In addition to their conductivity of the π-conjugated system of the main chain, these polymers contain heteroatoms such as N and O at high densities, which are believed to act as hydrogen bonding sites for stabilization of reaction intermediates. However, their exact structures and relationship to the catalytic activities are not fully grasped. In this study, we employ electro-polymerization as the mean to obtain catalytic polymers. Taking polyaniline (PANI) as the host, hydrogen bonding monomers such as dopamine (DA), guanine (GA) and neutral red (NR) are to be introduced to obtain co-polymers with controlled structure and density of the hydrogen bonding sites. Comparison of their electrocatalytic activity to those of the respective homo-polymers should reveal the effective catalytic sites and its product selectivity, which should result in optimal design of the catalyst. Electro-polymerization of PANI and PNR was carried out at an ITO glass substrate in an aqueous solution containing 50 mM ANI or NR and 0.1 M H2SO4 during 50 times potential cycling between -0.5 and +0.6 V vs. Ag/AgCl under the N2. Copolymers were obtained by mixing the monomers at appropriate ratios. The films were characterized by FT-IR spectra. PANI, PNR and their copolymer appeared dark green, dark red and black, respectively. While CVs during electropolymerization of PANI continue to increase the redox peaks of PANI as typically expected, those for PNR show decrease of anodic current suggesting inactiveness of PNR for its redox (Figs. 1 a, b). When they are mixed together, a new redox peak in between those from PANI and another irreversible anodic peak close to +0.9 V appear, which indicate loading of NR in redox active form into PANI (Fig. 1c). The FTIR spectrum of the copolymer showed significant difference from the homo-polymers of PANI and PNR with intense absorption peaks between 800 and 1600 cm-1 (Fig. 1d). These peaks arise from infrared-activated vibrations (IRAV) due to the presence of polaron in the main chain, thus are indicative of its conductive nature. These results suggest improvement of conductivity by heterogeneity in copolymers. Its relevance to the catalytic property and optimal density of hydrogen bonding sites are to be further investigated. References: 1. Coskun et al., Adv. 2017, 3, e1700686. 2. Coskun et al., adv mater interfaces, 2019, 1901364. Figure 1

The efficiencies of a series of hydrogen evolving catalysts based on metal oxide nanofibers (NiO, Co3O4, Mn3O4) are investigated for the photocatalytic hydrogen evolution from water without using any co-catalyst under the visible light irradiation by using triethanolamine (TEOA) as an electron donor and Eosin-Y (EY) dye as a photosensitizer. It is found that the photocatalytic hydrogen evolution activities follow the order as: Mn3O4

Cu2CoSnS4 (CCTS) nanofibers have been fabricated by electrospinning and exhibit an excellent morphology with an average nanofiber diameter of 150 nm. Polyacrylonitrile (PAN) was used as templating polymer that leads to a decrease in imperfections in the crystalline nanofibers. CCTS and Cu2ZnSnS4 (CZTS) nanofibers, based on abundant and environmental friendly elements, efficiently enhanced the rates of biphasic proton reduction in the presence of an organic solubilized electron donor, decamethylferrocene (DMFc). This work paves the way for the exploration of copper-based chalcogenides as electrocatalysts for the hydrogen evolution reaction to replace noble metal Pt.

We firstly demonstrate the synthesis of Cu 2 ZnSnSe 4-x S x (CZTSeS) nanofibers through versatile electrospinning technique. Polyacrylonitrile (PAN) was used as templating polymer that leads to decrease in imperfections on crystal fibers and yields outstanding structure including a few defects with diameter around 250 nm. Sulfurization and/or selenization processes were carried out separately and simultaneously depending upon the demanded chemical structure. Detailed characterization and electrochemical response indicate their potential application for solar cells as p-type semiconductors.

We report the synthesis of different colloidal CZTSe4−xSx nanocrystals and their performance in [6,6]-phenyl C61 butyric acid methyl ester (PCBM) based organic/inorganic hybrid bulk heterojunction solar cells. Synthesis of colloidal CuZnSnSe4−xSx were performed and characterized by XRD, TEM, SEM, UV–Visible absorption techniques. Electrochemical and photovoltaic properties were investigated. The best device concept, ITO/PEDOT:PSS/CZTS:PCBM blend (1:10)/Al, showed 280 μA/cm2 short circuit current, Isc with 300 mV open circuit voltage Voc, and fill factor FF of 0.38.

Conductive polydopamines represent bioinspired paradigm catalysts for efficiently recycling greenhouse gas CO2 to synthetic fuel., Selective electrocatalysts are urgently needed for carbon dioxide (CO2) reduction to replace fossil fuels with renewable fuels, thereby closing the carbon cycle. To date, noble metals have achieved the best performance in energy yield and faradaic efficiency and have recently reached impressive electrical-to-chemical power conversion efficiencies. However, the scarcity of precious metals makes the search for scalable, metal-free, CO2 reduction reaction (CO2RR) catalysts all the more important. We report an all-organic, that is, metal-free, electrocatalyst that achieves impressive performance comparable to that of best-in-class Ag electrocatalysts. We hypothesized that polydopamine—a conjugated polymer whose structure incorporates hydrogen-bonded motifs found in enzymes—could offer the combination of efficient electrical conduction, together with rendered active catalytic sites, and potentially thereby enable CO2RR. Only by developing a vapor-phase polymerization of polydopamine were we able to combine the needed excellent conductivity with thin film–based processing. We achieve catalytic performance with geometric current densities of 18 mA cm−2 at 0.21 V overpotential (−0.86 V versus normal hydrogen electrode) for the electrosynthesis of C1 species (carbon monoxide and formate) with continuous 16-hour operation at >80% faradaic efficiency. Our catalyst exhibits lower overpotentials than state-of-the-art formate-selective metal electrocatalysts (for example, 0.5 V for Ag at 18 mA cm−1). The results confirm the value of exploiting hydrogen-bonded sequences as effective catalytic centers for renewable and cost-efficient industrial CO2RR applications.

WOS:000399709300045 Ternary I-Cu2WS4 were synthesized based on hot-injection process and their thin films are prepared by spin coating techniques at ambient temperature. The energy dispersive analysis of X-rays of the thin films confirmed that synthesized thin film is stoichiometric. Transmittance and reflectance have been used to determine the optical, dispersion and dielectric properties of the Cu2WS4 in the range of 200-2400 nm. The transparency of the Cu2WS4 is 40-45% in the visible range. Optical dispersion parameters have been calculated by using the single term Sellmeier dispersion relation and Wemple-DiDomenico single oscillator model. Several dispersion parameters were determined by the analysis of refractive index dispersion.Absorption coefficient (alpha), extinction coefficient (), the Urbach energy (), real and imaginary parts of dielectric constant (epsilon) and surface and volume energy loss function have been calculated. The optical bandgap determined by the optical absorbance spectrum analysis showed that thin films possess a direct bandgap of 1.74 eV. Karamanoglu Mehmetbey UniversityKaramanoglu Mehmetbey University; Scientific Research Foundation [32-M-16]; TUBITAK (Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [215M309] We want to thank to Karamanoglu Mehmetbey University, Scientific Research Foundation for (32-M-16) financial support of this work. The authors would like to thank TUBITAK (The Scientific and Technological Research Council of Turkey) (215M309) for supporting this work.

Copper-based quaternary chalcogenide Cu2FeSnS4 (CFTS) is an important material due to its indium-free nature and presence of earth-abundant elements. Herein, CFTS nanofibers have been first fabricated via a facile two-step approach using a simple and inexpensive electrospinning technique. X-ray diffraction and scanning electron microscopy techniques were used to determine structural, morphological, and compositional features of the obtained films. Nanofibers annealed at 500 °C for 1 h were characterized by (112), (200), (220), (312) preferred orientations via X-ray diffraction method. Nanofibers showed well crystallization and tetragonal phase. The average diameters of obtained fibers were found to be 100 ± 50 nm. Cyclic voltammograms showed that CFTS fibers showed p-type behavior.

Photocatalytic generation of hydrogen by using oleic acid-capped CdS, CdSe, and CdS(0.75)Se(0.25) alloy nanocrystals (quantum dots) has been investigated under visible-light irradiation by employing Na(2)S and Na(2)SO(3) as hole scavengers. Highly photostable CdS(0.75)Se(0.25) alloy nanocrystals gave the highest hydrogen evolution rate (1466 μmol h(-1) g(-1)), which was about three times higher than that of CdS and seven times higher than that of CdSe.

A novel alginic acid derived tin catalyst, tin alginate (Sn–Alg), was successfully synthesized, characterized and applied for methyl esterification. Initially, the amount of catalyst, methanol to fatty acid ratio and reaction time were optimized using an oleic acid standard for esterification. The optimal reaction conditions were found to be 4% catalyst, 1 : 12 oleic acid to methanol mole ratio and 2 h reaction time with 98.7% fatty acid methyl ester recovery. The capability of Sn–Alg beads to esterify the fatty acids of corn deodorizer distillate was evaluated. High recovery (97.6%) of esters was obtained after 8 cycles using reprocessed catalyst under the optimized parameters. The results of the present study indicated that based on the environmental pollution, reusability, avoiding the use of potassium or sodium hydroxides or sulphuric or phosphoric acids, and ease of catalyst separation, the solid Sn–Alg catalyst has a great potential for biodiesel production from highly free fatty acid deodorizer distillates.

Sections ePDFPDF Tools Share Abstract Functional conductive polymers represent an emerging class of nonmetallic electrocatalysts attractive to substitute scarce and expensive elements used today. Here the synthesis of emeraldinepolyguanine as structuralmolecular analog to polyaniline is shown and the conducting biopolymer as molecular hydrogen electrocatalyst is applied. The polymerized and protonated nucleobase aids the catalytic electroreduction of protons over a peculiar mechanism, where, over aminoassociation, protons coserve as dopant and reactant. In acidic media the electrocatalytic evolution of hydrogen at a Tafel slope of 79 mV dec1 at 290 mV overpotential (10 mA cm2) is reported. The 140h initial stability test demonstrates that the functionality of polymerized nucleobases can be harnessed for heterogeneous catalysis, i.e., as here demonstrated for the electroconversion of hydrogen. (VLID)4844347 Version of record

The current study reports the application of chalcopyrite semiconductor CuInS

WOS: 000379182800001, PubMed: 27380957, The penternary chalcogenides Cu2CoSn(SeS)(4) and Cu2ZnSn(SeS)(4) were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV-Vis) spectroscopy. The Cu2CoSn(SeS)(4) and Cu2ZnSn(SeS)(4) nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18-25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu2CoSn(SeS)(4) nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu2ZnSn(SeS)(4) nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu2CoSn(SeS)(4) nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu2ZnSn(SeS)(4) nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu2CoSn(SeS)(4) nanocrystals in low-cost, high-efficiency, Pt-free DSSCs., Scientific and Technological Research Council of Turkey (TUBITAK Grant)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [214M366]; European Union through the COST Action MP1407 "Electrochemical processing methodologies and corrosion protection for device and systems miniaturization (e-MINDS)"; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [115M762], The authors would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK Grant Number 214M366) and also the European Union through the COST Action MP1407 "Electrochemical processing methodologies and corrosion protection for device and systems miniaturization (e-MINDS)" with TUBITAK (Grant Number 115M762) for the financial support of this research.

Bio-inspired and bioorganic materials gain outmost of interest due to a wide application area. In the past years, hydrogen-bonded organic semiconductors relying on indigoid pigment family are applied in various device geometries e.g. organic solar cells, organic field effect transistors but also as thin film electrodes in catalysis [1,2]. Currently, the integration of the bio-inspired materials in sustainable catalysis is powerful. Especially, organic functionalities present in the chemical structure of this new material class provide these compounds outstanding properties in terms of using these functional themes as catalytic active centers to substitute state-of-the-art metallic catalysts. Herein, we report on the suitability of a bio-originated polymer – Polydopamine (PDA) - as an effective electrocatalyst [3]. Polydopamine is a major pigment of the eumelanin family. Due to its hydrogen-bonded sequences in the conjugated structure, stabilized over hydroxyl, amine and carbonyl groups, PDA is a prominent competitor for the new generation of sustainable catalysis. We engineered a new synthetic pathway for the polydopamine electrode prepraration [4]. We apply the chemical vapor deposition technique in the presence of the monomer dopaminhydrochlorid together with sulfuric acid as an oxidant in order to form polydopamine films directly on 3D, sponge-like carbon felt electrodes, creating an increased catalytically active surface area. Electrochemical investigations exhibit the interaction and interplay of the functionalities in catalytic processes resulting in high yields and current densities and thus reducing energy losses. [1] Glowacki E. D.; Irimia-Vladu M.; Kaltenbrunner M.; Gasiorowski J.; White M. S.; Monkowius U.; G. Romanazzi G.; Suranna G. P.; Mastrorilli P.; Sekitani T.; Bauer S.; Someya T.; Torsi L.; Sariciftci N. S.; Adv. Mater., 2013, 25, 1563–1569. [2] Glowacki E. D.; Romanazzi G.; Yumusak C.; Coskun, H.; Monkowius U.; Voss G.; Burian M.; Lechner R. T.; Demitri N.; Redhammer G. J.; Sünger N.; Suranna G. P.; Sariciftci N. S.; Adv. Funct. Mater.; 2014, DOI: 10.1002/adfm.201402539. [3] Coskun, H.; Aljabour, A.; De Luna, P.; Farka, D.; Greunz, T.; Stifter, D.; Kus, M.; Zheng, X.; Liu, M.; Hassel, A. W.; Schöfberger, W.; Sargent, E. H.; Sariciftci, N. S.; Stadler, P.; Sci. Adv. 2017, 3 (8), e1700686 DOI: 10.1126/sciadv.1700686. [4] Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S.; 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063.

The electrochemical carbon dioxide reduction reaction (CO2RR) is attractive in terms of resolving the ever-growing release of CO2 from anthropogenic cause. Thereby, electrochemical CO2RR combines high energy-transfer yields and the refinement to versatile products such as C1- chemicals, which represent the concurrent carbon feedstock. Herein we explore the CO2 reducing property of nanofibrous chalcopyrite copper indium sulfide CuInS2 (CIS) and the pristine cobalt oxide (Co3O4), both p-type semiconducting materials, towards CO production mainly with remarkable faradaic efficiencies of 77% and 65%, respectively [1]. The focus in our studies are given to the utilization of the nanofiber electrodes as an appropriate electrocatalyst for CO production without using further expensive metal supplements, e.g. palladium, platinum, and potassium. Thus, the nanocrystalline shaping of nanofiber networks was achieved by the low-cost, versatile and time-saving electrospinning technique. In order to reduce the imperfection in the crystalline fiber, Polyacrylonitrile (PAN) was selected as template polymer [2]. The desired chemical structure of nanofibers was achieved through sintering process at 500 °C and 550 °C, respectively. With reasonable product selectivity by CuInS2 and pristine Co3O4 nanofibers [3] and a stable operation at a constant electrolysis potential for many hours, we think that this work will stimulate more exploration into using nanofiber based materials in energy recovery and carbon capture and utilization technologies. [1] Aljabour A.; Coskun H.; Apaydin D.H.; Ozel F.; Hassel A.W.; Stadler P.; Sariciftci N.S.; Kus M.; Applied Catalysis B: Environmental; 229; 2018; 163–170. [2] Ozel F.; Kus, M.; Yar, A.; Arkan, E.; Yigit, M. Z; Aljabour, A.; Büyükcelebi, S.; Tozlu, C.; Ersoz M, Materials Letters. 2015, 140, 23–26. [3] Aljabour A.; Apaydin D.H.; Halime Coskun, Ozel F.; Ersoz M.; Stadler P.; Sariciftci N.S.; Kus M.; ACS Appl. Mater. Interfaces 2016, 8, 31695−31701.

We report the room temperature (25–30°C) green synthesis of cobalt nanomaterial (CoNM) in an aqueous medium using gallic acid as a reducing and stabilizing agent. pH 9.5 was found to favour the formation of well dispersed flower shaped CoNM. The optimization of various parameters in preparation of nanoscale was studied. The AFM, SEM, EDX, and XRD characterization studies provide detailed information about synthesized CoNM which were of 4–9 nm in dimensions. The highly stable CoNM were used to study their catalytic activity for removal of azo dyes by selecting methyl orange as a model compound. The results revealed that 0.4 mg of CoNM has shown 100% removal of dye from 50 μM aqueous solution of methyl orange. The synthesized CoNM can be easily recovered and recycled several times without decrease in their efficiency.