bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction of TiS2 by OS Process in CaCl2 Melt
Authors: Suzuki Nobuyoshi , Tanaka M , Noguchi H , Natsui S , Kikuchi T , Suzuki Ryosuke O. 
Published: February 2020

Kroll process is composed a few independent thermal processes and consumes huge energy to produce metal Ti. OS process produces reductant Ca continuously in the molten salts and reduces directly Ti oxides to obtain metal Ti, which may become energy saving [1]. However, it is necessary to electrolyze for long time because the reduction speed is slow. To avoid severe problems in oxide reduction, we select TiS2 as raw material. Sulfur locates just below oxygen at periodic table, and many chemical properties are similar with oxygen. In addition, metallic Ti does not dissolve sulfur according to Ti-S binary phase diagram. Therefore, the step for sulfur removal from Ti-S solid solution can be skipped and a high quality of Ti is expected to be formed more quickly. A dry synthesis of TiS2 from TiO2[2] can be combined with the studied processes to recycle sulfur.
The purpose of this work is to examine the feasibility of thermochemical and electrochemical reduction of TiS2 by the electrolysis in the molten CaCl2to establish the new metal Ti manufacturing process.
Figure shows the results by the OS process at 1173 K in CaCl2-0.5mol% CaS melt. Concentration of sulfur decreased significantly at early stage. 0.043 mass %S was achieved when the stoichiometric charge Q0 was supplied, and 0.01 mass %S was achieved when Q = 4Q0 was supplied. Only Ti was identified by XRD at Q ≥ Q0. In stoichiometry, metal Ti and lower oxide were identified but no lower sulfide could be found.
The electrolysis rate could be improved when the larger amount of CaS is dissolved. However, concentration of residual sulfur in Ti increased as the addition of CaS increased.
In conclusion, 0.01mass%S could be obtained by the OS process. Addition of CaS could improve reduction rate, but impurity in Ti increased. It is possible to remove sulfur from Ti-S system, and the usage of Ti sulfide opens a new process of titanium refining process. Kroll process needs three steps to manufacture metal Ti, chlorinating, reduction by Mg, and electrolysis of MgCl2, while this new process needs only two steps, sulfide formation, and reduction by Ca. The authors desire the higher efficiency and energy saving using our proposal.

R
eferences

[1] R.O. Suzuki, K. Teranuma and K. Ono, Metall. Mater. Trans B, 34B, [6] 287 (2003).
[2] S.Hirai, M.Ohta, S.Satoh, and T.Kuzuta, Acta Materialia60 (2012) 7232-7240

Acknowledgements: This work was partly supported by the "Innovative Structural Materials Project (ISMA, Future Pioneering Projects)” and KOBE STEEL, LTD. The authors thank Prof. S. Hirai at Muroran Institute of Technology for discussion.

Figure 1
Probing Ionic Liquid/Electrode Interfaces by Hyperspectral Imaging
Authors: Malik Muhammad Kasim , Chrestenson Jacob R , Parr Daniel , Gray David , Mitiku H , Kahila Thomas , Malinowski Aleksander , Sánchez José , Haverhals Luke M. 
Published: February 2020

We will present data for experiments that probe structure and dynamics at ionic liquid (IL) and ionic liquid-based (IL-based) systems with electrode interfaces. IL-based electrolytes have been investigated for applications ranging from energy conversion devices (e.g., capacitors, batteries, fuel cells, and solar cells) to sensors. Fundamental characterizations of IL-based electrolyte/electrode systems can contribute toward engineered progress for these enterprises since adsorbed species and their associated interfacial dynamics play critical roles in determining device efficiencies. Our studies utilize surface enhanced infrared absorption (SEIRA) spectroscopy. In particular, we demonstrate hyperspectral imaging at an attenuated total reflectance crystal that has been modified with a nanostructured gold electrode. Imaging experiments characterize interfacial structure and dynamics between several ionic liquid media (compositions) at the electrode surface simultaneously during electrochemical perturbation. Our initial spectral imaging studies explore ILs composed of imidazolium-based cations with alkylsulfate, tetrafluoroborate, thiocyanate, dicyanamide, and bis(trifluoromethylsulfonyl)imide anions.
(Invited) Green Composites from Cellulose, Wool, Hair and Chicken Feather. Synthesis, Structure and Antimicrobial Property
Authors: Tran Chieu d 
Published: February 2020

Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simpleone-step process in which butylmethylimidazolium chloride (BMIm+Cl-), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl-] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of all three composites ([CEL+wool], [CEL+hair] and [CEL+feather]. The fact that feather has the lowest content of α-helix (and wool has the highest) enables the [CEL+ feather] composite to have strongest mechanical strength (and [CEL+wool] composite has the weakest strength). All three composites exhibit antibacterial activity against MRSA. The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool.
Mechanism of the Electrochemical Oxidation of Ammonia over Platinum: An in Situ attenuated Total Reflection Infrared Study
Authors: Katayama Yu , Okanishi Takeou , Muroyama Hiroki , Matsui Toshiaki , Eguchi Koichi 
Published: February 2020

The recent development of anion exchange membranes (AEMs) has increased the potential and the importance of ammonia as a fuel for anion exchange membrane fuel cells (AEMFCs). Although the reaction mechanism for the electrochemical ammonia oxidation over Pt electrode has been extensively studied, there is no report on the detection of the prospected intermediates and/or the poisoning species on Pt electrode.
In this study, the electro-oxidation of ammonia over Pt electrode in alkaline aqueous solutions was studied by in situ attenuated total reflection infrared (ATR-IR) spectroscopy. In the presence of NH3, the band ascribable to the HNH bending mode of adsorbed NH3 was confirmed at 1662−1674 cm−1 in the potential range of 0.1−1.1 V. The intensity of this band decreased continuously with a rise in potential, indicating the oxidative consumption of adsorbed ammonia. In response to this behavior, the band at 1269 cm−1 appeared alternatively above 0.2 V, and its intensity reached the local maximal value at ca. 0.4 V. Note that this potential of ca. 0.4 V agreed well with the onset potential of ammonia oxidation, ca. 0.45 V, in the linear sweep voltammogram. This 1269 cm−1 band was assigned to the NH2 wagging mode of N2H4, which was one of the active intermediates, N2H
x

+

y

,ad (x = 1 or 2, y = 1 or 2), according to the mechanism proposed by Gerischer and Mauerer. To the best of our knowledge, this is the first report for the detection of N2H4 as a reaction intermediate over Pt electrode. Furthermore, the formation of bridged NO was also observed above the onset potential of ammonia oxidation, ca. 0.5 V. Such adsorbed NO species probably inhibit the electrochemical reaction due to the occupation of reaction sites at higher potential.

Figure 1
Lanthanide Voltammetry: Electrocatalysis and Electrochemistry in Acetonitrile
Authors: Rathuwadu Nadeesha , Knoche Krysti L. , Leddy Johna 
Published: February 2020

An electrochemical method has been developed to allow voltammetric interrogation of lanthanides in common organic, electrochemical solvents [1, 2]. Lanthanide electrochemistry was enabled in acetonitrile at an ion exchange polymer (Nafion) modified platinum electrode with triflate ligands. Under these conditions, formal potentials of the lanthanides are shifted into the potential window of acetonitrile and voltammetry is enabled.
Here, voltammetry of lanthanides on the benchtop and evidence of electrocatalysis of reactions important in energy and environment are presented.
For several lanthanide triflate complexes, the voltammetry is reviewed. For five lanthanides, two reductions are observed under cyclic voltammetric conditions. For each lanthanide triflate complex, LN(OTf)3 where LN is a lanthanide, two well resolved reduction waves are observed. The first is for LN3+ to LN2+. The second wave about a volt negative of the first is for reduction of the LN(II) triflate. Under cyclic voltammetric conditions, the reverse sweep to positive potentials is less well resolved. The mechanistic path for the LN(OTf)3 is considered.
Electrochemical reactions of small molecule, ubiquitous species play important roles in energy and the environment. This includes the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), carbon dioxide reduction, and the chemistry of other organic species that contain one carbon, such as methanol, formic acid, formaldehyde, and carbon monoxide. Many of these reactions are kinetically limited. ORR limits performance of many fuel cell and air batteries. Increased rates of HER facilitate energy generation. The sequence of single carbon species both maps the thermodynamic advantages of organic electrochemical fuels and identifies the dominant kinetic limitations of their exploitation in practical, low temperature electrochemical energy systems. Carbon dioxide is the highest oxidation state of carbon and so the focus of study for reduction to regenerate fuels and value added products as well as to remediate greenhouse gases. Voltammetry undertaken in the presence of some of these species will be presented. For example, there is clear cyclic voltammetric evidence of increased rates of oxygen reduction in acetonitrile when lanthanide triflates are present in solution and the Nafion film on the electrode.
References
[1] Krysti L. Knoche, Ph.D., University of Iowa, 2014.
[2] J. Leddy and K. L. Knoche, “Lanthanide Electrochemistry,” Published U.S. Patent Application, 12 November 2015, 20150322581-A1.
(Invited) Molecular Hydrogen-Evolution Electrocatalysts for Dye-Sensitized Solar Fuels
Authors: Wu Yiying 
Published: February 2020

Proton reduction is one of the most fundamental and important reactions in nature. MoS2 edges have been identified as the active sites for hydrogen evolution reaction (HER) electrocatalysis. Designing molecular mimics of MoS2 edge sites is an attractive strategy to understand the underlying catalytic mechanism of different edge sites and improve their activities. Herein I will discuss our recent progress in this aspect. The first example is a dimeric molecular analog [Mo2S12]2-, as the smallest unit possessing both the terminal and bridging disulfide ligands. Our electrochemical tests show that [Mo2S12]2- is a superior heterogeneous HER catalyst under acidic conditions. Computations suggest that the bridging disulfide ligand of [Mo2S12]2- exhibits a hydrogen adsorption free energy near zero (-0.05 eV). The second example is a group of compounds with the general formular of MoO(S2)2bpy. By varying substitution on the bpy ligand, we demonstrate the induction effect on the S—S ligand, thereby tuning the rate constants for HER and overpotentials. We have studied homogenous electrocatalytic hydrogen production performance metrics of three catalysts with different bipyridine substitutions. By varying the electron-donating abilities, we present the first demonstration of using the ligand to tune catalytic properties of the S—S bond in molecular MoS2 edge site mimics. These works can shed light on the relationship between structure and electrocatalytic activity of molecular MoS2 catalysts and thus is of broad importance from catalytic hydrogen production to biological enzyme functions. Lastly, I will discuss how to integrate the molecular catalysts into dye-sensitized photoeletrochemical platforms for solar hydrogen production.
Effects of TiO2 nanoparticle Size on Solar-to-Hydrogen Efficiency in Photoelectrochemical Cells
Authors: Bonning Bo , Salimijazi Farshid , Shirvanian Pezhman 
Published: February 2020

The photocatalytic splitting of water into oxygen and hydrogen using solar light is a promising clean and renewable source for hydrogen fuel1. Metal-oxides are one type of material that researchers are studying to overcome this scientific challenge. TiO2 is one of the most studied and promising photocatalysts. This is due to TiO2 having a band gap with edge positions that makes it capable of splitting water. However, due to its large band gap (3.0-3.3eV) hindering its ability to utilize portions of the solar spectrum, TiO2 has a low solar-to-hydrogen efficiency2. Therefore, steps have been made to improve this material. Going to nanoscale has shown to have potential, but research comparing different sized nanoparticles hasn’t been as prevalent as other methods, such as doping. Having smaller particle size, particularly in the lower nanometer range, can give materials unique properties that could increase photoactivity3. Some properties, such as quantum confinement, aren’t as beneficial for large band gap materials like TiO2. When a material reaches a small enough size, quantum confinement effects take over, changing the electrochemical properties. One of these properties is the band gap energy, which increases as particle size decreases4. Therefore, it is imperative to find a particle size that gives a material the most optimal balance of these effects, leading to a material with the highest water splitting efficiency. The purpose of this study was to test the differences in efficiencies, such as solar-to-hydrogen efficiency (STH), of TiO2 for decreasing nanoparticle size. Nanoparticle sizes ranging from 100 nm down to 5 nm were tested using photoelectrochemical(PEC) measurements. It was our prediction that smaller particle size will result in an overall increase in photoactivity, as per other literature3, and therefore a higher solar-to-hydrogen efficiency (STH). The process of putting together the working electrode, as well as procedure and results of experiments, will be discussed.
References
[1] Marschall, R. (2014). Semiconductor composites: strategies for enhancing charge carrier separation to improve photocatalytic activity. Advanced Functional Materials, 24(17), 2421-2440.
[2] Khan, S. U., Al-Shahry, M., & Ingler, W. B. (2002). Efficient photochemical water splitting by a chemically modified n-TiO2. science, 297(5590), 2243-2245.
[3] Almquist, C. B., & Biswas, P. (2002). Role of synthesis method and particle size of nanostructured TiO 2 on its photoactivity. Journal of Catalysis,212(2), 145-156.
[4] Alivisatos, A. P. (1996). Semiconductor clusters, nanocrystals, and quantum dots. Science, 271(5251), 933.
Photocatalytic Degradation of Phenolic Compounds in Presence Electrogenearated O3 and or H2O2
Authors: Al-Kandari Halema Ali , Abdullah Aboubakr Moustafa , Al-Kandari Shekhah Ali , Mohamed Ahmed meslam 
Published: February 2020

A Graphene oxide (GO) was prepared using modified Hummer`s method starting from graphite. GO was impregnated on commercial nanoparticles P25 TiO2 (GOTi) or WO3. After that, reduced GOTi or GOWO3 was obtained by hydrothermal reduction. The photocatalysis behavior of as-prepared catalysts were tested towards the phenolic compounds degradation and compared against commercial P25 TiO2 in presence and absence of in-situ electrochemically generated ozone. The SiO2/Ti300nm/Pt100nm/TiOx100nm/SnOx500nm electrode was used to produce ozone electrochemically. Table 1 showed that the photocatalytic degradation rate constant of phenol on RGOTi under Xe illumination in presence of H2O2 and electrochemically generated ozone is the better than TiO2.
Table 1: Rate constant data in min-1 of phenol (20 mg L-1) on Ti and RGOTi under 150 Xe illuminations in absence and absence of 70 µL H2O2 and Ozone

Xe
Xe + H2O2

Xe + O3

Xe + H2O2 + O3

Ti
RGOTi
Ti
RGOTi
Ti
RGOTi
Ti
RGOTi

0.0214
0.0226
0.0296
0.032
0.0257
0.0262
0.0375
0.0615
Fabrication of WO3/BiVO4 p-n Junction Photoanode for Efficient Solar Water Splitting
Authors: Seo Hyungtak , Kalanur Shankara S. 
Published: February 2020

Photo-electrochemical (PEC) water splitting for hydrogen production is one of the most attractive renewable energy technologies as it directly converts solar energy to chemical energy. And hence, it could play a central role in hydrogen-based energy economy of future. Efficient photo-catalytic water splitting requires effective generation, separation and transfer of photo-induced charge carriers that can hardly be achieved simultaneously in a single material. Hence, using single inorganic semiconductors faces a limitation and leads to decrease in overall efficiency of the PEC. Therefore, p–n junction photo-anodes can be very effective as they can facilitate the separation of the photo-generated electron–hole pairs. In this work, a p–n junction having n type WO3 and p type BiVO4 photo-anode has been designed and fabricated. This junction dramatically showed higher photocurrent density compared to individual WO3 and BiVO4 electrodes. We achieve one the highest photocurrent of 4.2 mA/cm2 at an potential of 1.23 V versus a reversible hydrogen electrode (RHE) under simulated sunlight without an added catalyst. In the composite WO3/BiVO4 film a shifted quasi-Fermi level results, due to electronic equilibration between the two materials. The better performance of WO3/BiVO4 hetero-junction electrodes is thus a consequence of the electron injection from BiVO4 into WO3, Thin layer (5 nm) of amorphous TiO2 was deposited on the photo-anode using electrochemical deposition. The deposition was noticed to be uniform and complete on the photo-anode and increases the photo-stability of the photo-anode for longer times. The strategies for constructing such kind of hetero-junctions are well applicable to other dual bandgap photo-anodes.
(Invited) Hybrid Photocatalysts Consisting of Metal Complexes and Semiconductors for CO2 Reduction
Authors: Ishitani Osamu 
Published: February 2020

Both the problems of the global warming and shortage of the fossil resources have brought about great interest in photochemical utilization of CO2 with solar energy. Efficient photocatalysts for CO2 reduction must be necessary for development of such an important technology.

We have developed novel types of photocatalytic systems using metal complexes and/or semiconductors as a photocatalyst. I will focus on the following systems in my presentation.

(1)
Architecture of supramolecular photocatalysts driven with visible light, which can efficiently reduce CO2 selectively to CO or HCOOH.

1-10

(2)
Z-scheme type photocatalysts by using hybrids composed with the supramolecular photocatalyst and a semiconductor, which can reduce CO2 with methanol as an electron donor.11-14

(3)
Photoelectrochemical systems with metal-complex photocatalyt adsorbed on p-type semiconductor electrodes, which can reduce CO2 with water as an electron donor.15

References:

[1].
Gholamkhass, B.; Mametsuka, H.; Koike, K.; Tanabe, T.; Furue, M.; Ishitani, O. Inorg. Chem. 2005, 44, 2326.

[2].
Sato, S.; Koike, K.; Inoue, H.; Ishitani, O. Photochem. Photobiol. Sci. 2007, 6, 454.

[3].
Koike, K.; Naito, S.; Sato, S.; Tamaki, Y.; Ishitani, O. J Photochem. Photobiol. A: Chem. 2009, 207, 109.

[4].
Tamaki, Y.; Watanabe, K.; Koike, K.; Inoue, H.; Morimoto, T.; Ishitani, O. Faraday Discuss. 2012, 155, 115.

[5].
Tamaki, Y.; Morimoto, T.; Koike, K.; Ishitani, O. Proc. Natl. Acad. Sci. USA 2012, 109, 15673.

[6].
Tamaki, Y.; Koike, K.; Morimoto, T.; Yamazaki, Y.; Ishitani, O. Inorg. Chem. 2013, 52, 11902.

[7].
Tamaki, Y.; Koike, K.; Morimoto, T.; Ishitani, O. J. Catal. 2013, 304, 22.

[8].
Tamaki, Y.; Koike, K.; Ishitani, O. Chemical Science 2015, 6, 7213

[9].
Tamaki, Y.; Koike, K.; Ishitani, O. Chemical Science 2015, 6, 7213.

[10].
Nakada, A.; Koike, K.; Maeda, K.; Ishitani, O. Green Chemistry 2016, 18, 139.

[11].
Sekizawa, K.; Maeda, K.; Domen, K.; Koike, K.; Ishitani, O. J. Am. Chem. Soc. 2013, 135, 4596.

[12].
Yoshitomi, F.; Sekizawa, K.; Maeda, K.; Ishitani, O. ACS Appl. Mater. Interfaces 2015, 7, 13092.

[13].
Nakada, A.; Nakashima, T.; Sekizawa, K.; Maeda, K.; Ishitani, O. Chemical Science 2016 in press (DOI 10.1039/C6SC00586A).

[14].
Kuriki, R.; Matsunaga, H.; Nakashima, T.; Wada, K.; Yamakata, A.; Ishitani, O.; Maeda, K. J. Am. Chem. Soc. in press (DOI 10.1021/jacs.6b01997).

[15].
Sahara, G.; Abe, R.; Higashi, M.; Morikawa, T.; Maeda, K.; Ueda, Y.; Ishitani, O. Chem. Commun. 2015, 51, 10722.

Figure 1
(Invited) Development of Photocatalytic and Photoelectrochemical CO2 Reduction System
Authors: Ohno Teruhisa , Kamimura Sunao 
Published: February 2020

Morphology controlled brookite TiO2 nanorod having brookite phase was developed. Exposed crystal surfaces play different roles such as oxidation and reduction, respectively. These properties are a great advantageous for multi-electron reaction such as CO2 reduction. We also investigated the co-catalysts loading effects for improving CO2 reduction. The maim product for CO2 reduction was methanol The photocatalytic activates of brookite TiO2 nanorods loaded with Ag or Rh were about 10 times higher than that of brookite TiO2 without co-catalysts loading. The apparent quantum efficiency of the reaction reached to about 3 % under UV light.
We had also developed g-C3N4/WO3 nanocomposite photocatalysts for CO2reduction to generate methanol, CO, CH4, and formic acid under visible light Among the several kinds of products, methanol was obtained as a main product. Co-catalysts loading effect such as Ag, Au had been also investigated. The reaction mechanism was investigated by using double beam pohtoacoustic spectroscopy.
Several kinds of photoelectrochemical systems for CO2 reduction by using B-doped g-C3N4, CuCrO2, Cu3Nb2O8 photocatalysts electrodes had been developed in order to separate the products such as CO, methanol, etc.. The photocurrent responses for CO2 reduction using the g-C3N4 electrodes improved by Boron doping and co-catalysts coating such as Au, Ag, Rh etc on the surface of the electrodes. The main product of this photoelectronchemical system was ethanol. The photocurrent responses of CuCrO2 and Cu3Nb2O8 electrodes were about 10-30 times higher than that of the Boron doped g-C3N4 coted with Rh photoelectrode. The detailed discussion of these results will be presented at the presentation.
We had also developed CZTS (Cu2ZnSnS4) photoelectrode covered by ZnS, CdS or In2S3 for CO2 reduction. ZnS, CdS or In2S3 played a role for an electron correction layer and protection layer. The photocurrent response for H+ reduction and CO2 reduction was drastically improved by covering CdS or In2S3 thin layer. Faraday efficiency of H2, CO evolution and HCOOH generation are about 60, 1.5, and 2.5 %, respectively. The effects of CdS, In2S3, and metals co-catalyst loading will be discussed.