bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stable and Active Polymer Electrolyte Membrane Electrolyzers Utilizing Transition Metal Phosphide Hydrogen Evolution Catalysts
Authors: King Laurie Ann , Hubert McKenzie , Capuano Christopher B , Manco Judith , Danilovic Nemanja , Hellstern Thomas , Jaramillo Thomas F 
Published: February 2020

Electrochemical water splitting utilizing renewable electricity is a promising technology for the production of clean and sustainable hydrogen. The most active electrocatalyst for the hydrogen evolution reaction (HER) is platinum. However, the high costs and scarcity associated with platinum motivate the search for alternative catalysts.1 Promising HER activities have been reported for many families of materials including transition metal chalcogenides, carbides and in particular, phosphides.2 Specifically, cobalt phosphide (CoP) is an interesting and active non-precious metal HER catalyst in acid media.3

In this work we synthesise active and stable CoP catalysts on carbon supports at the 1 – 5 g batch scale. The CoP catalysts are prepared by wetness impregnation Vulcan carbon followed by a red phosphorous based vapour phase phosphidation. The crystal structure and chemical composition of the CoP catalyst is verified by XPS and XRD. The morphology of the catalyst is shown to consist of <20 nm particles on the surface of Vulcan carbon support by SEM. The synthesised CoP catalysts are first screened by laboratory scale three-electrode electrochemistry and demonstrate good activity for HER requiring an overpotential of 154 mV to reach -10 mA.cm-2. Beyond three-electrode laboratory scale electrochemistry screening, the most active and durable HER catalysts were used to fabricate 25 cm2 single cell stack membrane electrode assemblies (MEA). The performance of the CoP MEAs was assessed by polarization curve as well as steady state measurements at various current densities and were found to be stable for >20 h of testing. This work highlights the remarkable stability and promise of transition metal phosphides in an MEA configuration.

References

(1) Ng, J. W. D.; Hellstern, T. R.; Kibsgaard, J.; Hinckley, A. C.; Benck, J. D.; Jaramillo, T. F. ChemSusChem
2015, 8 (20), 3512.
(2) Seh, Z. W.; Kibsgaard, J.; Dickens, C. F.; Chorkendorff, I.; Nørskov, J. K.; Jaramillo, T. F. Science
2017, 355 (6321), eaad4998.
(3) Hellstern, T. R.; Benck, J. D.; Kibsgaard, J.; Hahn, C.; Jaramillo, T. F. Adv. Energy Mater.
2016, 6 (4), 1501758.
(Invited) Observation of the Marcus Inverted Region of Electron Transfer from Asymmetric Chemical Doping of Pristine (n,m) Single-Walled Carbon Nanotubes
Authors: Kunai Yuichiro , Liu Albert Tianxiang , Cottrill Anton , Koman Volodymyr , Liu Pingwei , Kozawa Daichi , Gong Xun , Strano Michael S 
Published: February 2020

The concept of electrical energy generation based on asymmetric chemical doping of single-walled carbon nanotube (SWNT) papers is presented. We explore 27 small, organic, electron-acceptor molecules that are shown to tune the output open-circuit voltage (VOC) across three types of pristine SWNT papers with varying (n,m) chirality distributions. A considerable enhancement in the observed VOC, from 80 to 440 mV, is observed for SWNT/molecule acceptor pairs that have molecular volume below 120 Å3 and lowest unoccupied molecular orbital (LUMO) energies centered around −0.8 eV. The electron transfer (ET) rate constants driving the VOC generation are shown to vary with the chirality-associated Marcus theory, suggesting that the energy gaps between SWNT and the LUMO of acceptor molecules dictate the ET process. When the ET rate constants and the maximum VOC are plotted versus the LUMO energy of the acceptor organic molecule, volcano-shaped dependencies, characteristic of the Marcus inverted region, are apparent for three distinct sources of SWNT papers with modes in diameter distributions of 0.95, 0.83, and 0.75 nm. This observation, where the ET driving force exceeds reorganization energies, allows for an estimation of the outer-sphere reorganization energies with values as low as 100 meV for the (8,7) SWNT, consistent with a proposed image-charge modified Born energy model. These results expand the fundamental understanding of ET transfer processes in SWNT and allow for an accurate calculation of energy generation through asymmetric doping for device applications.
Reference: J. Am. Chem. Soc., 2017, 139 (43), 15328–15336
Conversion Reaction Synthesis: A Versatile Route to Nanoporous Transition Metals
Authors: Coaty Christopher , Zhou Hongyao , Liu Haodong , Liu Ping 
Published: February 2020

Nanoporous Metals (NPMs) are nanostructured pure metals with pores ranging from approximately 1-100 nm in diameter. They have been sought-after for their unique combinations of metallic characteristics and nanostructured size-effect properties, ranging from catalysis, plasmonics, battery electrodes to actuators. Many synthesis routes for nanoporous metals have been developed in the past 30 years, the oldest and most popular being the dealloying method. This method involves chemically or electrochemically removing the less-noble element from an alloy, leaving behind a nanoporous metal. Other techniques include combustion synthesis, block-copolymer templating, or directed assembly of metal nanoparticles.
Here, we demonstrate a scalable, room temperature synthesis method capable of producing a variety of nanoporous metal structures. Nanoporous Fe, Co, Au, Cu, Ag and Ni were formed by reacting metal-halide salts with organolithium reducing agents to form a metal/lithium salt nanocomposite. During this conversion reaction, the metal phase coalesces into an interconnected network of fine metal filaments surrounded by a lithium salt matrix. When the lithium salt is removed via dissolution in a polar organic solvent, the metal filament network remains and is an effective nanoporous pure metal (See Figure 1 for representative images). Nitrogen adsorption analysis and microscopy studies showed that these materials have high specific surface area (up to ~160 m2/g) with pore diameters ranging from 2 nm to 50 nm. This technique can also synthesize hybrid nanoporous structures of two or more metals by performing the conversion reaction on mixed precursors. Metals (e.g. Co and Cu) were found to stabilize each other when converted into a hybrid nanoporous structure, resulting in a mixed nanoporous metal with smaller pore sizes and higher surface areas than each respective element in its pure nanoporous metal form. This synthesis pathway greatly expands our access to new compositions and microstructures of nanoporous metals.

Figure 1
(Invited) Biological Imaging Using up-Conversion Photoluminescence of Carbon Nanotubes
Authors: Miyauchi Yuhei 
Published: February 2020

Single-walled carbon nanotubes (SWNTs) have been considered as nearly ideal luminescent probes for deep-tissue bioimaging because of their photoluminescence in near-infrared range known as the second optical window of biological tissues [1]. Moreover, efficient phonon-assisted up-conversion photoluminescence (UCPL) in SWNTs, for which the excitation light wavelength can be longer than the emission one, has recently been discovered [2, 3]. The UCPL phenomena enable SWNTs excited at wavelengths longer than ~1050-1200 nm to emit PL shorter than 1000 nm in which standard Si-based detectors have finite sensitivity. The availability of the UCPL thus potentially enhances the usefulness of SWNTs as luminescent probes in their bioimaging applications. We will report our recent progress in whole-body imaging of living mice with negligible autofluorescence using UCPL of SWNTs. We will also discuss application of the UCPL phenomena of SWNTs for near-infrared optical thermometry.
[1] K. Welsher, Z. Liu, S. P. Sherlock, J. T. Robinson, Z. Chen, D. Daranciang, and H. Dai, Nat. Nanotechnol. 4, 773 (2009). [2] N. Akizuki, S. Aota, S. Mouri, K. Matsuda, and Y. Miyauchi, Nat. Commun. 6, 8920 (2015). [3] S. Aota, N. Akizuki, S. Mouri, K. Matsuda, and Y. Miyauchi, Appl. Phys. Express 9, 045103 (2016).
Part of this study was supported by the Research Foundation for Opto-Science and Technology, the Nakatani Foundation, and by JSPS KAKENHI Grant Number JP15H05408.
(Invited) Development of Nanostructured Mesoporous Carbon As a Support and Catalyst for Fuel Cell Application
Authors: Pak Chanho , Lee Bong Ho , Lee Ji Yeon , Lee Seung Woo , Kim Do Hyung , You Dae Jong , Kim JI Man 
Published: February 2020

In recent years, polymer electrolyte fuel cells (PEFC) using hydrogen and methanol as fuel, respectively, have been attracting interest because the application areas of PEFC is expanding in the fuel cell electric vehicle, household fuel cell and portable fuel cell [1,2]. In this fuel cells, electricity is directly generated by electrochemical reactions such as hydrogen and methanol oxidation reaction at the fuel electrode and oxygen reduction reaction(ORR) at the air electrode, thus providing a high electrical efficiency and environmentally friendly. To carry out such an electrochemical reaction in the electrode, the supported catalyst on which the active precious metal is dispersed with high dispersion is essential [1,2]. That is, the supported catalyst is usually composed of a support and catalytically active elements such as Pt, Pd, Ru. In general, carbon materials having a high electrical conductivity, a large specific surface area, and a high chemical stability is applied as a support for an electrochemical catalyst [2]. Among the nanostructured carbon materials, the ordered mesoporous carbon (OMC), which have a large surface area and very well-connected the mesopores has been developed as a novel support for the fuel cell applications [3,4]. In this presentation, I would like to explain the brief history of the development of OMC support by authors for the PEFC such as direct methanol fuel cell and proton exchange membrane fuel cell. For example, Pt supported on the S-containing OMC(S-OMC) showed a higher thermal stability compared to the carbon black and pure OMC due to the strong metal-support interaction [5]. In addition, composite support between OMC and SiC for enhancing the catalytic stability of Pt toward the ORR will be presented as a recent example [6]. The composite supports are prepared by changing the temperature for the carbonization process during the nano-template method [6]. The SiC contents in the composite support were increased by increasing the temperatures. The Pt catalyst supported on the composite support showed excellent activity stability for ORR compared to the Pt particles on the pristine OMC and commercial Pt/C catalyst.
[1] Y.-J. Wang, N. Zhao, B. Fang, H. Li, X. T. Bi, and H. Wang, Chem. Rev.,115, 3433 (2015).
[2] C. Wang, S. Wang, L. Peng, J. Zhang, Z. Shao, J. Huang, C. Sun, M. Ouyang, and X. He, Energies, 9, 603 (2016).
[3] A. Eftekhari and Z. Fan, Mater. Chem. Front., 1, Advance Article (2017).
[4] H. Chang, S. H. Joo, and C. Pak, J. Mater. Chem. 17, 3078 (2007).
[5] H. I. Lee, S. H. Joo, J. H. Kim, D. J. You, J. M. Kim, J.-N. Park, H. Chang, and C. Pak, J. Mater. Chem., 19, 5934 (2009).
[6] D. J. You, X. Jin, J. H. Kim, S.-A. Jin, S. Lee, K. H. Choi, W. J. Baek, C. Pak, and J. M. Kim, Int. J. Hydrogen Energy, 40, 12352 (2015).
(Invited) Highly Stabilized Perovskite Solar Cells By Li-Ion-Containing Fullerene Salt As Both Dopant and Anti-Oxidant
Authors: Matsuo Yutaka , Jeon Il , Ueno Hiroshi 
Published: February 2020

Lead halide perovskite solar cells (PSCs) have drawn great attention as the promising solar energy source in recent years. Their certified power conversion efficiencies (PCEs) now reach more than 20%. Despite high PCE, low stability of PSCs has been the most serious drawback, which is in dire need of resolution. It has been found that light, oxygen, and water are the origins of the perovskite layer degradation. In particular, dopants used for 2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenylamine)-9,9’-spirobi-fluorene (spiro-MeOTAD) hole-transporting material are attributed for the low stability, due to their hygroscopic nature. Replacement of liquid electrolyte by spiro-MeOTAD was a breakthrough at the initial stage of PSC development, improving PCE substantially, owing to well-aligned energy band and amorphous nature of spiro-MeOTAD. However, because spiro-MeOTAD intrinsically has low mobility, a dopant must be present to improve the conductivity. Lithium bis(trifluoromethanesulfonyl)imide salt (Li+TFSI−) has been widely used as the p-dopant for spiro-MeOTAD. Li+TFSI− does not directly oxidize spiro-MeOTAD, but instead, promotes the oxidation of spiro-MeOTAD by oxygen at the presence of light or thermal excitation. Because doping spiro-MeOTAD with Li+TFSI− requires oxygen, it is difficult to control the amount of spiro-MeOTAD oxidation; the formation of oxidized spiro-MeOTAD has been shown to be reversible during device operation depending on ambient conditions and the sweep direction of current−voltage (J
−V) measurement. Also, a number of factors, including light intensity, the concentrations of lithium ions and oxygen, has been shown to the amount of oxidized spiro-MeOTAD. Uncontrolled oxidized spiro-MeOTAD is unpredictable and leads to inconsistent reproducibility and instability of PSCs. In addition to this, as mentioned above, Li+ salt is extremely hygroscopic and induces moisture-based degradation of PSCs.
In this work, lithium-ion-encapsulated [60]fullerene bis(trifluoromethanesulfonyl)imide salt ([Li+@C60]TFSI−) was used in PSCs instead of Li+TFSI− as a solution aforementioned problems. C60 encapsulating Li+ changed the hydrophilic alkali salt to a hydrophobic species. Also, spiro-MeOTAD mixed with [Li+@C60]TFSI−produced cationic salt spiro-MeOTAD●+TFSI− and neutral Li+@C60
●− by electron transfer from spiro-MeOTAD to Li+@C60. While spiro-MeOTAD●+TFSI−functioned as an effective hole transporting material Li+@C60
●− functioned as an antioxidant, reacting with any intruding oxygen and moisture. spiro-MeOTAD●+TFSI− required no chemical additives nor oxidation as it was technically pre-oxidized spiro-MeOTAD. By preventing unnecessary oxidation in the device system, [Li+@C60]TFSI−-used devices showed approximately 10 times higher stability than the conventional Li+TFSI−-used devices.

Figure 1
(Invited) Structural Identification of 19 Purified Isomers of Opv Acceptor Material Bis[60]PCBM
Authors: Liu Tong , Abrahams Isaac , Dennis John 
Published: February 2020

The molecular structures of 19 purified isomers of bis-phenyl-C62-butyric acid methyl ester (“bis[60]PCBM”) were identified by a combination of 13C NMR and UV-Vis absorption spectroscopy, and HPLC retention time analysis. The 13C NMR spectra indicated the symmetry of each isomer. It also showed that all 19 isomers are dicyclopropa-fullerenes (none are homo-fullerenes). This is because the fullerene bridgehead for both addends are sp
3 hybridized; resonating between 75 and 85 ppm. According to UV-Vis spectroscopy, the 19 isomers were classified into 7 groups - each corresponding to one of the 7 bond types identified by Hirsch and co-workers (trans-1, trans-2, trans-3, trans-4, e, cis-3, cis-2).
All 58 nominal molecular structures of Bis[60]PCBM were accounted for by isolating the first addend as bridging fullerenes carbon 1 and 9 by default, after which the 2nd addend may to one of the 29 remaining double bonds on C60 with two orientations relative to that of the 1st addend. However, symmetry reduced this number to 36 physically distinguishable isomers. Many of these isomers have enantiomers, and hence cannot be spectroscopically distinguished; which reduces the number of effective isomers to 22. If these, 3 are not expected to form owing to steric hindrance because each of these three isomers involve the cis-1 bond whereby the bulky addends would be attached to two adjacent double bonds on the same 6-membered ring on C60.
There were 7 isomers with C1 molecular point group symmetry, 4 with CS, 6 with C2, 1 with C2v and 1 with C2h symmetry. The C2h, C2v, and all 5 non-equatorial C1 molecular structures were unambiguously assigned to their respective HPLC fractions. For the other 12 isomers, the 13C NMR and UV-Vis spectra placed them in 6 groups of two same-symmetry isomers. Based on the widely spaced HPLC retention times of the two isomers within each of these 6 groups, and the empirical inverse correlation between retention time and addend spacing, each molecular structure was assigned to its corresponding HPLC fraction.
The information presented will enable those who follow and produce photovoltaic devices based purified isomers to know which specific isomer is being employed in their devices, develop a deeper understanding of morphological order/disorder within the acceptor phase, and thereby draw meaningful conclusions on why some isomers perform better than others.
(Invited) What Can Electrochemistry Learn from Chess?
Authors: Dawson-Elli Neal , Mitra Kishalay , Subramanian Venkat R. 
Published: February 2020

Batteries are complex electrochemical devices whose short-term and long-term operational lives are highly dependent on their construction, materials, and use cases. Models have been developed and used to improve the performance of batteries by providing different material design, model based control and model based battery management systems1,2.
In recent literature, data science techniques have been used to accomplish a variety of tasks related to representing simulated data for control or estimation purposes2,3,4
. Data science techniques have also been used to approximate optimal solutions to computationally difficult problems, such as the traveling salesman problem5. Rather than create a surrogate model to use with a typical optimization scheme, we will examine framing the problem as a parameter ‘correction’ endeavor. By doing so, it may be possible to retain all of the information present in a time series of error and leverage this information to very quickly go from a poor initial guess to a viable solution, after which time iterative optimization schemes can take over. The effectiveness of this approach (both in terms of efficiency and robustness) will be compared with the standard approaches. This method is inspired by DeepChess, a comparative deep neural network structure which plays successfully against world-class chess algorithms4.

Acknowledgments

The authors thank the United States Department of Energy (DOE) for the financial support for this work though the Advanced Research Projects Agency – Energy (ARPA-E) award #DEAR0000275, as well as the Clean Energy Institute (CEI) through the DIRECT program at the University of Washington. Part of the research has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U. S. Department of Energy through the Advanced Battery Materials Research (BMR) Program (Battery500 Consortium)

References

Y. Dai, and V. Srinivasan,. J. Electrochem. Soc., 163, A406 (2016).

N. Dawson-Elli, S. B. Lee, M. Pathak, K. Mitra, and V. R. Subramanian, “Data Science Approaches for Electrochemical Engineers: An Introduction through Surrogate Model Development for Lithium-Ion Batteries,” J. Electrochem. Soc., vol. 165, no. 2, pp. A1–A15, Jan. 2018.

D. A. C. Beck, J. M. Carothers, V. R. Subramanian, and J. Pfaendtner, “Data science: Accelerating innovation and discovery in chemical engineering,” AIChE J., vol. 62, no. 5, pp. 1402–1416, May 2016.

Blake R. Hough, author. Jim Pfaendtner, degree supervisor. 2016 Thesis (Ph. D.)--University of Washington,2016.

B. La Maire and V. Mladenov, “Comparison of Neural Networks for Solving the Travelling Salesman Problem,” in 11th Symposium on Neural Network Applications in Electrical Engineering,NEUREL 2012 - Proceedings, 2012.

E. David, N. S. Netanyahu, and L. Wolf, “DeepChess: End-to-End Deep Neural Network for Automatic Learning in Chess,” arXiv:1711.09667 [cs, stat], vol. 9887, pp. 88–96, 2016.
(Invited) Interface Modification for Efficient Charge Transfer in Perovskite Solar Cells
Authors: Murakami Takurou N 
Published: February 2020

Power conversion efficiencies of the perovskite solar cells (PSCs) are drastically increased in this 5 years. PSCs without a mesoporous TiO2 layer, planar-type cells, commonly obtained poorer cell performance as compared to cells with a porous TiO2 layer, owing to inefficient electron transfer from the perovskite layer to the compact TiO2 layer in the former case. The matching of the conduction band edge (CBE) levels of perovskite and the compact TiO2 layer is thus essential for enhancing solar cell performance. In this work, we discussed about the interface between perovskite and electron transport layer (ETL) to improve the performance of the PSCs with adjustment of the CBE levels for reducing the energy loss at the material interfaces in the PSCs. The CBE levels were evaluated with the electrochemical methods.
The chemical bath treatment with TiCl4 (TiCl4 treatment) for the compact TiO2 layer to increase the performance of PSC has been reported. The effect of the TiCl4 treatment was considered as the cause of the wettability increases of the precursor solution of the perovskite on TiO2 compact layer and the efficient charge transport from perovskite layer to TiO2 layer. However, TiCl4 treatment may change the CBE potentials. The adjustment of the CBE potentials will be important issue to obtain the low barrier potentials for electron transfer from perovskite to TiO2 compact layers. To study the effect of the TiCl4 treatment on the CBE potentials, we prepared the electrochemical cells with the iodide and tri-iodide redox electrolyte and treated substrate with TiCl4 aqueous solution and the relation between open circuit voltages (
V
oc) and the electron density in TiO2 layer of the cells were measured with the charge extraction methods. The V
oc as the quasi CBE potential was negatively shifted with the TiCl4 treatment but positively shifted with heating after TiCl4 treatment. We compared the PSCs performance as the different heating temperature at 150 °C, 300 °C, and 450 °C of the TiCl4 treated compact TiO2 layers. The Voc was decreased and the short circuit current was increased with increasing the temperature. The highest PCE was obtained with the heating at 300 °C.