bluuebunny/crossref_metadata_2025_split huggingface dataset:
Building Block Design for Rapid Mass Transport in Quasi-Solid-State Solar Cells
Authors: Cui Lingling , Zhang Xiao LI 
Published: December 2020

Mesoscopic solar cells have rapidly emerged as a promising alternative to conventional silicon photovoltaics due to the combined benefits of low-cost, simple fabrication and competitive solar energy conversion efficiency. Recent success in low light absorption cobalt (II/III) polypyridyl complexes has led to encouraging solar energy conversion efficiencies in excess of 13%. Moreover, as one-electron redox mediators, cobalt (II/III) complexes based DSC systems also show a lower overpotential for dye regeneration and better compatibility with flexible metal substrates than iodide/tri-iodide. Such efforts open up great possibilities towards commercial applications.
In contrast to the conventional organic liquid electrolytes that commonly have challenges durable encapsulation of the devices due to solvent evaporation, gel electrolytes have exhibited an impressive long-term stability, especially for outdoor applications where temperature of the DSC system can reach 80-85 oC under sunlight. Improvement on mass transport of the considerably large sized cobalt (II/III) complexes, particularly in high viscosity electrolyte, is crucial for solid-state dye-sensitized solar cells (SS-DSCs) to reach a reliable high efficiency toward practical applications.
In this work, titania nanorod aggregates (TNA) with a great specific surface area and well-developed crystalline network were synthesized through a solvothermal approach and utilized as photoanode building blocks for application in cobalt (II/III) tris(2′2-bipyridine) complexes based solid-state electrolyte. An initial efficiency excess 7.1% and a long term stable efficiency of approximately 8.0% were achieved at full sun illumination by freshly assembled and aged TNA SS-DSCs, respectively. This represents dramatic enhancements of nearly 35% and 100% against the SS-DSCs prepared from two standard TiO2 nanoparticle samples – CCIC (approx. 5.9%) and Degussa P25 (approx. 4.0%), correspondingly. The TNA is characterised by a combination of mesopores within each aggregate and macro inter-aggregates voids, a high specific surface area and a great light scattering ability; such features make the aggregates superior photoanode building blocks for the application in bulky cobalt redox mediator based SS-DSCs system.
Oxygen Reduction Reaction Activity of Iron (II) Phthalocyanine Monolayers in Acidic Media Studied Using a Rotating Disk Electrode Technique
Authors: Toyama Tatsuya , Motobayashi Kenta , Ikeda Katsuyoshi 
Published: December 2020

Metal complexes such as metalloporphyrins and metallophthalocyanines are widely studied in various research fields due to their unique physical and chemical properties. Especially, their catalytic activities for oxygen reduction reaction (ORR) are of great interest because this reaction plays an important role in energy conversion or biological redox processes. Among various metal complexes, Iron (II) phthalocyanine (FePc) is expected as a candidate for four-electron ORR catalysts. However, most of the kinetic studies for ORR have been carried out using heat-treated catalysts of FePc. Unfortunately, their chemical structures become ill-defined after the heat treatment, and thus, the nature of active sites is still unclear. Actually, there is a possibility that four-electron ORR activity is induced by dimeric FePc. The intrinsic activity of monomeric FePc, especially in acidic media, is still under discussion. In this study, well-defined monolayers of monomeric FePc complexes were fabricated on chemically modified Au surfaces using two-step assembly [1]. Their ORR activity was quantitatively measured in acidic media using a rotating disk electrode (RDE) technique. The catalytic behavior of FePc was compared with that of Cobalt (II) tetraphenylporphyrins (CoTPP), which is known as two-electron ORR catalyst.
The monolayers of FePc or CoTPP were fabricated on Au surfaces as follows. First, an Au disk electrode with diameter of 10 mm was modified with self-assembled monolayers of pyridine-4-thiol (PySH) or 1,6-diisocyanohexane (C6DI). Next, metal complexes of FePc or CoTPP were immobilized on top of these molecular monolayers through axial ligation with their different terminal groups. The ORR activity of these samples was measured in O2-saturated 0.05 M H2SO4 aqueous solution using the RDE method.
Figure shows rotation rate dependences of RDE polarization curves for CoTPP and FePc on C6DI-modified Au. According to the Koutecky-Levich analysis of these curves at 0 V vs. RHE, the electron transfer number was estimated to be 1.9 for CoTPP, indicating that CoTPP indeed catalyzed only two-electron ORR. On the other hand, the estimated transfer number for FePc was 2.4, suggesting that this complex was indeed able to catalyze the four-electron ORR in the acidic condition. Interestingly, the catalytic behavior of FePc on C6DI-modified Au was apparently different from that on PySH-modified Au. In the poster, we will present details about the ORR activities of FePc measured on various monolayer-modified Au electrodes.
Reference
[1] Toyama T, Sato S, Motobayashi K, Uosaki K, Ikeda K. J Solid State Electrochem. DOI: 10.1007/s10008-019-04461-9.
Figure. Rotation rate dependence of RDE polarization curves for FePc/C6DI/Au and CoTPP/C6DI/Au measured in 0.05 M H2SO4 solution, where FePc/C6DI/Au and CoTPP/C6DI/Au denote FePc and CoTPP monolayers immobilized on C6DI-modified Au, respectively.

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Electropolishing of Type 304 Stainless Steel in an Amide Type Ionic Liquid Containing Chloride Ion
Authors: Yuza Nitaro , Serizawa Nobuyuki , Katayama Yasushi 
Published: December 2020

Electropolishing of stainless steel (SUS) has been commercially performed in such aqueous acid solutions as phosphoric and sulfuric acid. The current process shows low current efficiency due to the oxygen evolution reaction. Amide type ionic liquids with wide electrochemical windows are expected as an alternative electrolyte for electropolishing of metals with high current efficiency. Although electropolishing of Ti, Cu, Pt, and Sn has been reported in amide type ionic liquids, there is no report for SUS. In addition, previous studies on electropolishing of SUS in nonaqueous electrolytes have suggested that chloride ions are necessary to promote the breakdown of the oxide film on SUS. In the present study, the anodic dissolution mechanism of type 304 SUS was investigated in an amide type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) amide (BMPTFSA), containing chloride ions.
BMPTFSA containing Cl- was prepared by dissolving BMPCl. The anodic behavior of SUS was investigated by linear sweep voltammetry. The surface morphology and roughness of SUS before and after the anodic dissolution were evaluated by scanning electron microscopy and laser scanning microscopy.
A smooth and shiny surface was obtained by the anodic dissolution with optimum conditions in BMPTFSA containing Cl-. The surface roughness decreased after the anodic dissolution. On the other hand, no anodic current corresponding to the anodic dissolution of SUS was observed in BMPTFSA without Cl-, indicating the presence of Cl- is necessary for the anodic dissolution of SUS in an amide type ionic liquid. The dissolved metal ion species in the ionic liquid were identified to be the chlorocomplexes of Fe, Cr, and Ni by ultraviolet-visible spectroscopy. The current efficiency of anodic dissolution was estimated to be 93 to 100% from the mass change of the electrode and electric charge, suggesting that electropolishing with high current efficiency is possible.
The present work was partially supported by the Kato Foundation for Promotion of Science.
Enhancement of Photogenerated Charge Transport By TiO2 Modification of WO3/BiVO4 Core-Shell Heterojunction
Authors: Park Eunoak , Lee Kiyoung 
Published: December 2020

Photoelectrochemical (PEC) water oxidation is a promising approach to generate hydrogen using solar light. For the purpose, several candidate materials are considered that are mostly semiconductive materials including metal oxide. Among various metal oxides, WO3 has been regarded as a prospective resource because of their suitable band position, relatively higher photocorrosion resistance, and low cost. WO3 allows photogenerated electrons and provide easy electron pathway to current collector through the conduction band. Furthermore, BiVO4 deposition on WO3 can attract hole from WO3 that plays a key role for oxygen evolution reaction. Nevertheless, BiVO4 has a drawback to be solved with respect to stability. For this reason, blocking layers with high band gap energy are suggested to protect the unstability. In particular, TiO2 has not only high band gap energy but also chemical/physical stability. Moreover, TiO2 blocks solution-mediated recombination at surface of WO3/BiVO4 core-shell heterojunction, which helps to improve PEC efficiency.
In the present work, we achieve facile approach to modify WO3/BiVO4 with TiO2 deposition. As a result, photoinduced current density is recorded as 0.59 mA cm−2 at 1.23 V vs. reversible hydrogen electrode (RHE) under AM 1.5 G illumination. This value makes 78.8µL cm-2 of H2 evolution, which indicates almost 1.5 times higher than the WO3/BiVO4 core-shell heterojunction.

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Enhancement of Photoelectrochemical Properties through α-Fe2O3 Deposition on a Modified Fluorine-Doped Tin Oxide
Authors: Choi Yongseon , Lee Kiyoung 
Published: December 2020

Hydrogen is attractive energy resource for renewable energy. In order to produce H2, several approaches are suggested. In particular, water splitting is well-known as an eco-friendly production approach. Moreover, electrochemical water splitting has a challenge that noble metal based catalyst. For this reason, photoelectrochemical (PEC) water splitting has been studied for a long time but not yet to reach a goal of society demand.
For PEC water splitting, there are several materials has been considered such as Fe2O3, WO3, TiO2, BiVO4 etc. Among them, Fe2O3 is the most attractive material due to cheap, abundant resources and smaller bandgap than other material. However, it has a demerits of short life time owing to short diffusion length.
In this research, we investigated enhancement of PEC performance with electrodeposited Fe2O3 on surface modified fluorine-doped tin oxide (FTO). The roughness of FTO substrates were increased with various electrochemistry method in acidic electrolyte. The modified FTO substrate area which leads to increasing electric conductivity. Under optimum condition photocurrent could be enhance with 20% in compare with α–Fe2O3 on pristine FTO substrate. Moreover, over-potential was also reduced with 100 mV.

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Exploring the Optoelectronic Properties of Solution Processed 2D TMD Nanoflakes Exfoliated Via Large Molecule Electrointercalation
Authors: Wells Rebekah , Caretti Marina , Cho Han-Hee , Sivula Kevin 
Published: December 2020

The remarkable semiconducting properties of 2D transition metal dicalcogenides (TMDs) are of great interest to researchers hoping to harness such traits for optoelectronic and photoelectrochemical (PEC) applications. 2D MoS2, WSe2, and related materials have been incorporated in ultrathin devices including transistors1, LEDs2, solar cells3, and photoelectrodes4,5. While typical approaches like chemical vapor deposition produce pristine monolayer or few-layer 2D TMD sheets and flakes, these methods are expensive and energy intensive making them unsuitable for large scale implementation. Thus, developing scalable solution processable methods to prepare high-quality 2D TMD materials is crucial.
Typical solution-based production approaches have historically yielded TMDs with poor semiconducting behavior. Recently a novel electrointercalation technique was reported by Lin et al. wherein large organic cations are inserted in between MoS2 layers in a bulk single crystal thereby exfoliating it to thin nanoflakes while maintaining benchmark semiconducting performance. Despite this advance, there remains a lack of information concerning the optoelectronic properties of these flakes and their ability to be used in solar energy conversion devices.
Herein we use the electrointercalation of large cation tetraheptylammonium bromide (THAB) to exfoliate a variety of bulk TMDs, investigate their optoelectronic properties, and process them into photoelectrodes for solar-to-chemical energy conversion. When compared to alternative solution processing methods such as ultrasonication and shear-mixing exfoliation, these THAB-assisted exfoliated flakes show increased photocurrents, photovoltages, and internal quantum efficiencies. We show that this is, in part, a result of thinner 2D flakes with larger lateral dimensions. Raman, photoluminescence, and X-ray spectroscopy suggest that this technique results in a lower defect density when compared to traditional methods. These results suggest that THAB-intercalated 2D TMDs are promising for scalable solar energy applications.
References:
1. Lin, Z.; Liu, Y.; Halim, U.; Ding, M.; Liu, Y.; Wang, Y.; Jia, C.; Chen, P.; Duan, X.; Wang, C.; Song, F.; Li, M.; Wan, C.; Huang, Y.; Duan, X. Nature
2018, 562 (7726), 254–258.
2. Palacios-Berraquero, C.; Barbone, M.; Kara, D. M.; Chen, X.; Goykhman, I.; Yoon, D.; Ott, A. K.; Beitner, J.; Watanabe, K.; Taniguchi, T.; Ferrari, A. C.; Atatüre, M. Nat. Commun.
2016, 7 (1), 12978.
3. Akama, T.; Okita, W.; Nagai, R.; Li, C.; Kaneko, T.; Kato, T. Sci. Rep.
2017, 7 (1), 11967.
4. Wells, R. A.; Johnson, H.; Lhermitte, C. R.; Kinge, S.; Sivula, K. ACS Appl. Nano Mater.
2019, 2 (12), 7705–7712.
5. Yu, X.; Prévot, M. S.; Guijarro, N.; Sivula, K. Nat. Commun.
2015, 6, 7596.
(Invited) Skin-Mimic Hydrogel Materials with Water-Perspiration Control for Soft Robots Developed by 3D Printing
Authors: Kanai Shuma , Watanabe Yosuke , Shiblee MD Nahin Islam , Khosla Ajit , Ogawa Jun , Kawakami Masaru , Furukawa Hidemitsu 
Published: December 2020

In medical and welfare fields, the developments of robots and prosthesis with the touch close to the human skin are required. For those developments, the use of materials with a touch, softness, temperature, and moisture close to human skin is necessary. Hydrogels are materials with their high water content (90 ~ 95%) and softness (kPa to hundreds of kPa). However, hydrogels have some technical drawbacks such as high water evaporation rate, their touch and temperature different from that of human skin.
We designed a flow channel inside the hydrogel to mitigate the mass loss due to drying of the gel by supplying and circulating warm water with a perista pump. The water absorption and evaporation of the gel were investigated for designing the optimum water channel dimensions. With this mechanism mass loss due to drying was decreased by 43%.
We also fabricated a hydrogel hand using 3D printer. Inside the gel hand, bone parts printed with poly lactic acid are embedded. We are planning to make water channel in the gel hand and adjust the composition of the hydrogel to finally create a gel hand with a touch similar to the human skin.

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(Invited) Fabrication of Polymer Gels with Double Network Using Multi-Material 2/3D Printing
Authors: Watanabe Yosuke , Shiga Fumiya , Shiblee MD Nahin Islam , Ogawa Jun , Khosla Ajit , Kawakami Masaru , Furukawa Hidemitsu 
Published: December 2020

Multi-material systems for additive manufacturing, also known as 3D printing, are used to fabricate the functional objects with different color materials or with the position dependent material properties such as elastic modulus or solubility. The previous work for Fused Deposition Modeling (FDM) method have demonstrated that the multiple print heads or a single head with the mixed-material systems can extrude the complex and composite materials with piling up the multi-material layers connected with the physical bonds between layers.However, few studies have focused on the fabrication of 3D printed gel materials with different materials, and the creation of chemical bonds on the interface between the multi-material layers.
In our previous work, 3D printed hollow objects made of gel materials were fabricated with a customized optical 3D printing system, and the 3D printed objects of multifunctional ionic gels incorporating ionic liquid (IL) in the thiol–ene network of thiol-based end-crosslinker and acrylate monomers were fabricated using commercial stereolithography (SLA) system. It was found that optical 3D printing system utilized to fabricate gel materials could create the microscale objects.
This study report the design and fabrication of 3D printed polymer gels containing two types of gels using 3D gel printer named “SWIMER”. The double network technique for hydrogels is used for the creation of chemical bonds between two types of gels. Figure shows one of examples of 3D printed gel.This gel consists of two parts: the soft body frame for structural support which is made of nonionic polymer gels and the part which is made of the ionic polymer gels. The nonionic gels with an ordered structure are synthesized by the polymerization of the monomer, N,N-Dimethylacrylamide (DMAAm), and the crosslinker, N, N'-Methylenebisacrylamide (MBAA). The ionic gels are synthesized by the polymerization of the monomer, N-(1,1-Dimethyl-2-(sodiosulfo)ethyl)acrylamide and the same chemicals as the nonionic gels. Chemicals as the ultraviolet (UV) initiator are depending on the wavelength of laser source in the process of how we fabricate the gels.The significant difference in the swelling behavior between the two parts enabled them to be actuated in one direction. We found that by controlling the ion concentration in water they enlarged the solvent-induced strains to 108% in water which is comparable to the polymer actuators driven with high voltage.

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Biomolecule Exchange Dynamics on Carbon Nanotubes Via Multiplexed Fluorophore Quenching
Authors: Pinals Rebecca , Yang Darwin , Lui Alison , Cao Wendy , Landry Markita P 
Published: December 2020

Adsorption of biomolecules on single-walled carbon nanotubes (SWCNTs) has enabled developments in molecular sensing, in vivo imaging, and gene delivery applications.1,2 This noncovalent functionalization of SWCNTs preserves the pristine SWCNT atomic structure, thus retaining the intrinsic near-infrared fluorescence for sensing or imaging functions, and offers a reversible binding mode for cargo delivery. However, biomolecule adsorption is an inherently dynamic process, where exchange occurs between molecules in the bulk solution and molecules on the nanoparticle surface, into what is known as the corona phase. The nature, strength, and kinetics of both the biomolecule binding and unbinding processes on SWCNTs are important contributors to the success of SWCNT-based technologies. Understanding this binding process is especially important for intended uses of functionalized SWCNTs in biological environments, where native biomolecules such as proteins compete with the original biomolecule to occupy the SWCNT surface. Such biofouling of the SWCNT surface disrupts the intended functionality of the nanoparticle and can further lead to adverse biocompatibility outcomes.
We present a generalizable method to study the corona exchange dynamics between solution-phase and corona-phase biomolecules on SWCNTs in real-time.3 This approach exploits the quenching property of fluorophores proximal to the SWCNT surface to monitor ligand binding and unbinding events. Real-time tracking of adsorption and desorption events on the SWCNT surface are conducted with systematic variation of the molecular entities and solution conditions, with a specific focus on DNA (as the sensing moiety) and protein (as the biofouling agent). Binding profiles are extracted from the experimental assay and used to inform a kinetic model of the system. The work presented herein develops an understanding of the fundamental corona exchange mechanism and provides insight into performance of these designed SWCNT-based systems in biologically relevant, protein-rich conditions.

References

Demirer, G. S. et al. High aspect ratio nanomaterials enable delivery of functional genetic material without DNA integration in mature plants. Nature Nanotechnology 1 (2019) doi:10.1038/s41565-019-0382-5.

Beyene, A. G. et al. Imaging striatal dopamine release using a nongenetically encoded near infrared fluorescent catecholamine nanosensor. Science Advances
5, eaaw3108 (2019).

Pinals, R. L., Yang, D., Lui, A., Cao, W. & Landry, M. P. Corona Exchange Dynamics on Carbon Nanotubes by Multiplexed Fluorescence Monitoring. J. Am. Chem. Soc. (2019) doi:10.1021/jacs.9b09617.

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Electrophoretic Deposition of Carbon Nanotubes for Anti-Reflective Coatings
Authors: Wang Dan , Fuqua Peter , Hopkins Alan , Hennessy Amber , Hall Timothy , Snyder Stephen , Inman Maria , Taylor E. J. 
Published: December 2020

Space observatory missions requires the development of low-reflectivity surfaces for space-borne instruments, such as seeker telescopes, optical sensors, etc., to minimize stray and reflected light across the visible and infrared wavebands for facilitating the direct exoplanet detection and characterization. For example, in order to improve the sensitivity of missile-defense sensors and seekers, baffles are used within optical telescopes to reduce stray light. Some materials (e.g., aluminum, beryllium, etc.) are too reflective to use as absorptive baffles without surface processing, although they have lightweight and good thermo-structural properties, and survive harsh environments. Black surface coating treatments have been demonstrated as effective approaches to obtain low reflective surfaces. The surface features and intrinsic properties of the coating materials play an important role for scattering, absorbing, or trapping light. The excellent optical absorption performance and light weight of carbon nanotubes (CNTs) make them as ideal coating materials for obtaining low reflectivity surfaces. In this presentation, we will discuss the feasibility of a low-cost, efficient and scalable manufacturing process for the deposition of durable, low reflectivity carbon nanotube black coatings based on the use of pulse and pulse reverse electrophoretic deposition technology. The low-reflectivity CNT coatings have been successfully deposited on various surfaces, including flat, bent, and sharp substrates. The CNT coatings show the reflectance of 0.4% ~ 0.8% across visible to near infrared (NIR) wavebands.
Within this context, Faraday Technology Inc. demonstrated the feasibility of a low-cost, efficient and scalable manufacturing process for the deposition of durable, low reflectivity carbon nanotube black coatings based on the use of pulse and pulse reverse electrophoretic deposition. As shown in Figure 1, the uniform CNT coatings are formed on an aluminum (Figure 1, Inset (Right)), and the diffuse reflectance of the CNT coatings is ~ 0.5% over the visible range. We also demonstrated the potential to apply CNT coating on the internal diameter of cylinders at room temperature (Figure 1, Inset (Lef)t). Faraday are currently working on developing CNT coatings on the surface of absorptive baffle materials, such as beryllium and aluminum. The developed economic and scalable technology for producing CNT black coatings on desired substrates can not only be used for minimizing stray and reflected light for space-borne instruments, but also offer potential applications in other optical related devices which request low reflective surfaces, such as solar cells.

Acknowledgements: The financial support of NASA SBIR/STTR program through contracts No. 80NNSC18P2062 & 80NSSC19C0177 is acknowledged.

Figure 1