bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Structure Design and Controlled Synthesis of Metal Electrocatalysts of High Surface Energy and High Activity
Authors: Sun Shi-Gang 
Published: February 2020

Metal nanoparticles play a key role as electrocatalysts in electrochemical energy conversion, electosynthesis and other important fields. The electrocatalytic nanoparticles depend strongly both on their bulk and surface structures. The bulk structure could be tuned by changing the chemical nature and composition, while tuning the surface structure is more difficult, especially the high activity corresponding to high surface energy that leads to disappear the nanoparticles during their growth. We have focused, in recent years, on the structure design and controlled synthesis of nanoparticle electrocatalysts of high surface energy, prepared platinum group metal-based electrocatalysts through the development of electrochemical methods, and investigated systematically their catalytic property towards fuel cell applications.
(1) Tuning the surface atomic arrangement of well-defined metal nanocatalysts. Well-defined Pt, Pd and Rh nanocrystals enclosed by high-index facets have been successfully obtained by developing electrochemically shape-controlled synthesis, such as tetrahexahedral nanocrystals (THH NCs) enclosed with {hk0} high-index facets, trapezohedral nanocrystals (TPH NCs) with {hkk} high-index facets, triambic icosahedral nanocrystals (TIH NCs) with {hhl} high-index facets and hexoctahedral Pt NCs (HOH NCs) with {hkl} facets. As high-index facets containing a high density of active centers, these NCs exhibit high electrocatalytic activity for small organic fuel oxidation reactions as anodic reactions of direct Fuel Cells.
(2) Tuning the electronic structure of Pt- and Pd-based nanocatalysts. The electronic structure of NCs catalysts has been turned either by surface decoration using foreign adatoms, or through alloying Pt and Pd with other metals. Different adatoms such as Bi, Ru and Au were used to decorate the THH Pt NCs, and both THH and TPH Pt-based alloy nanocatalysts were prepared by electrochemically shape-controlled synthesis. The THH and TPH alloy NCs preserve the high-index facets while hold a synergy of electronic effect that enhances further the electrocatalytic activity.

Acknowledgements. The studies were supported by NSFC (21361140374, 21229301, and 21321062)

References:

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Chem. Soc., 2010, 132: 7580.

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Chem. Int. Ed., 2010, 49: 411.

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Rev., 2011, 40: 4167.

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Tian Na et al. Faraday Discuss., 2013, 162 : 77.

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Chem. Soc., 2013, 135: 18754.

Yu Neng-Fei et al. Angew. Chem. Int. Ed., 2014, 53: 5097.
Microbial Fuel Cell Prototyping for Pilot-Scale Applications
Authors: Jones Jason , Chen Shing , Phan Tony , Chan Shirley , Babanova Sofia , Phadke Sujal , Bretschger Orianna 
Published: February 2020

Utilizing anode-respiring bacteria, microbial fuel cells (MFCs) are a technology that is able to remove organic materials from waste streams and generate electricity in the process. MFCs have been considered as an alternative to conventional wastewater treatment using activated sludge, due to potentially lower cost of operation (no pumping of oxygen) and the ability to directly control the removal of organics.
Our study is focused on designing modular and scalable MFC reactors that can be utilized in pilot-scale installations. We tested several operational parameters and two different anode electrode configurations to study the effect on current production and chemical oxygen demand (COD) removal. The operational parameters included running the systems in MFC-mode with a constant resistance, alternating open circuit/closed circuit operation (open circuit for 30 minutes, once a day), and applying a set voltage to the circuit. The different anode electrode configurations included graphite-coated stainless steel bolts or carbon fiber brushes. All of the reactors utilized the same gas diffusion oxygen reducing cathode design. Samples were taken daily to evaluate the COD removal rates, monitor/control pH, and determine the concentration of dissolved oxygen in the reactors. Current production was monitored in real-time and polarization measurements were executed periodically for the electrodes to evaluate the activities of the associated microbial communities at the anodes, as well as the efficiency of cathode operation.
Reactors under alternating open circuit/closed circuit operation demonstrated improved performance longevity than those held under constant resistance (MFC-mode). This may be a result of decreased biofouling on the cathode per our previous work[1] or improving the charge storage capacity of the anode biofilms[2]. Our preliminary results showed that lowering the applied resistance to 22Ω yielded current production up to ~15 mA and COD removal rates of 55 mg/L/day, as compared to a resistance of 560Ω, which yielded ~1mA and 21 mg/L/day, respectively. In regards to anode material performance, our studies showed that carbon fiber brushes allowed for COD removal rates over 10 times higher than the coated stainless steel bolts, and up to an additional ~8mA of current production. Future work will include an analysis of COD removal and current production normalized by electrode surface area and electrode-associated biomass to better compare results and elucidate the system parameters that are highly correlated to improved MFC performance.

Figure 1
Redox-Active Poly(ionic liquid)s As Active Materials in Energy Devices
Authors: Hernandez Guiomar , Isik Mehmet , Mecerreyes David 
Published: February 2020

Poly(ionic liquid)s emerged from the incorporation of ionic liquids into polymers and have gained interest due to a wide range of applications in different technological fields such as polymer electrolytes for batteries and supercapacitors. Poly(ionic liquid)s provide enhanced mechanical stability, processability and spatial controllability over ionic liquids in electrolyte applications.
Incorporation of redox-active groups into poly(ionic liquid)s brings new possibilities to these materials in the energy field. Here we will present the combination of poly(diallyldimethylammonium) type poly(ionic liquid)s with redox-active counter-anions based on anthraquinone and nitroxide groups. First, we will present the electrochemical properties of the redox active poly(ionic liquid)s. Second, the potential use of these materials in different applications such as electrocatalysts for oxygen reduction reaction, cathodes in lithium batteries and redox flow batteries will be presented.
(Invited) Searching New Materials for Efficient Solar Driven Hydrogen Production
Authors: Yan Yanfa 
Published: February 2020

Using sunlight and semiconductors to split water in a photoelectrochemical (PEC) process to generate hydrogen provides a viable way to produce renewable fuel. So far, the efficient PEC devices are exclusively based on epitaxial grown III-V semiconductors. However, these semiconductors are expensive to make, limiting their practical application for large scale PEC hydrogen production. PEC devices based on polycrystalline thin films can potentially lead to low-cost production of hydrogen by PEC. However, most PEC devices made of polycrystalline thin films have not achieved high efficiency yet. Searching for new semiconductors that can potentially lead to efficient PEC devices is still necessary. In this talk, we will present general strategies for searching for such kind of semiconductors. We will show by density-functional theory that some new chalcogenides and oxides are promising candidates for efficient PEC applications. We will also present our latest results on experimental assessments on these new PEC materials.
(Invited) Unassisted CO2 Photoconversion at Copper Oxide Electrodes
Authors: Nath Narayan Chandra Deb , Choi Seung Yo , Park Hyunwoong , Lee Jae Joon 
Published: February 2020

Artificial photosynthesis of value-added chemicals from CO2 and water has received renewed attention and diverse technical solutions for high efficiency and durability systems have been explored. The photoelectrochemical (PEC) systems have been demonstrated to be technically viable with a number of semiconductor photoanodes (e.g., WO3, BiVO4, etc.) coupled to metal (Cu, Au, Ag, etc.) or metal oxide electrodes (CuO and Cu2O), as well as photocathodes (Si, Cu2O, CuO2, CuFeO2, etc.) coupled to metal/metal oxide anodes for CO2 photoconversion. A photoelectrochemical cell, composed of WO3/dye-sensitized solar cell and copper oxide wire arrays, is demonstrated as an unassisted, durable device for CO2 photoconversion. The high surface-to-volume copper oxide wire exhibits a promising electrocatalytic activity of CO2 reduction reaction at faradaic efficiencies of ~80% and ~60% at E = -0.2 and -0.4 V vs. RHE, respectively. The single-absorber cell of a WO3 photoanode and copper oxide wire cathode couple requires the minimum overpotential (h) of 0.7 V to drive CO2 conversion. In the unassisted cell, the long-wave band (l > ~450 nm) passes through the semi-transparent WO3 film is absorbed by dye. The unassisted cell shows a potential gain of ~0.7 V, successfully driving the CO2 conversion without any external power supply.
Convenient and Efficient Surface Reforming of LaTiO2 N Photocatalyst: Poly(4-styrenesulfonic acid) Treatment and Microwave Assisted CoO
x
Deposition
Authors: Akiyama Seiji , Yamada Taro , Domen Kazunari 
Published: February 2020

The overall water splitting by solar-energy-driven photocatalysts is a crucial issue as a solution for today’s mass scale energy and environmental problems. The activity of those photocatalysts is to be improved by their surfaces where the water splitting reactions take place. This time we report two useful tips to enhance the efficiency of LaTiO2N, an important candidate oxynitride for photocatalysis. One is to clean off the debris and defects on the particle surface. Domen et al.1 reported a brief, effective aqua regia treatment was in removing surface defects of LaTiO2N. However, aqua regia accompanies drawbacks of its severe reactivity. We need quick, elaborate washing to stop etching of the oxynitride in a contolled manner, and we need to isolate the aqua regia’s corrosive fume from the environment. More convenient and effective altanative surface treatment reagents are wanted in this sense. Two is to modify the surface of LaTiO2N with CoO
x
nanoparticles as so-called co-catalysts. The co-catalysts are supposed to assist the separation of photogenerated charges as well as promotion of surface reactions to evolve O2. CoO
x
nanoparticles, composed of earth abundant elements, are conventionally loaded by the liquid impregnation/calcination method.2 However the process of calcination on LaTiO2N brings about a complexity of heating in NH3 flow to avoid surface oxidation, simultaneously introducing chances of CoO
x
particle sintering and metallization. Our solutions for there problems are by rinsing in aqueous poly(4-styrenesulfonic acid) (PSS) solution followed by loading CoO
x
with a microwave assisted deposition. Static treatment of the LaTiO2N powder in PSS solution for 17 hours and microwave assisted one-pot loading of CoOx with Co(NH3)3Cl3 in Eyleneglycol solution, prior to fabrication into an electrode, increased the photoanodic current up to 8.9 mA cm-2 at 1.23 VRHE, which is 3 times larger than that without these reforming. We also confirmed that LaTiO2N was treated with PSS solution conveniently and care-freely in comparison with etching in aqua regia, and cocatalyst was coated throughout the surface of LaTiO2N particle by using microwave quick heating.

M. Matsukawa, R. Ishikawa, T. Hisatomi, Y. Moriya, N. Shibata, J. Kubota, Y. Ikuhara and K. Domen, Nano Lett. 2014, 14, 1038−1041.

F. Zhang, A. Yamakata, K. Maeda, Y. Moriya, T. Takata, J. Kubota, K. Teshima, S. Oishi and K. Domen, J. Am. Chem. Soc.,
2012, 134, 8348−8351.

Figure 1
Ultralow Power Gas Sensing for Societal Well-Being
Authors: Carter Michael T , Stetter Joseph R , Findlay Melvin W , Meulendyk Bennett J. , Peaslee David 
Published: February 2020

Recent years have witnessed an explosion of chemical and physical sensing technologies driven by the Internet of Things (IoT), the advent of commercial wearable technologies and the rise of point of care diagnostics . Business analysts expect these trends to continue to grow substantially over the next decade. This growth will provide ever increasing opportunities in sensor science and technology, particularly those aimed at wearables, as well as medical diagnostics and general health and wellness awareness in the home and environment.
This presentation will review some of our recent work in the area of next-generation electrochemical gas sensors for environmental and health/safety applications. Specifically, we will present on new hardware developed for wearable and other applications requiring ultralow power operation and its application to several areas including ozone monitoring for asthma sufferers, wearable environmental gas sensors and the detection and characterization of odors.
DNA Electrochemical Hybridization Detection in Droplets Using Gold Ultramicroelectrodes in a Two-Electrode Configuration
Authors: Horny Marie-Charlotte , Lazerges Mathieu , Siaugue Jean-Michel , Pallandre Antoine , Haghiri-Gosnet Anne-Marie , Gamby Jean 
Published: February 2020

Biosensors are all about the limit of detection1 imposed by the molecular level changes in expression of biomolecules to hope to perform reliable diagnostics before symptoms of a disease appears. A special interest was driven to the DNA target, mimicking the liver-specific micro-Ribonucleic Acid 1222 (miRNA122). DNA hybridization is the most prized method compared to direct sequencing all the more now that long range electron transfer through the DNA duplex π-staking has been demonstrated3. The electronic coupling within its inner core of stacked array of heterocyclic aromatic base pairs is very sensitive to local disruptions such as mismatches making a DNA biosensor particularly sequence specific. In a DNA biosensor, the target sequence is recognized by a complementary DNA probe and hybridized. The basis pairing according to Watson and Crick’s rules4 is converted into an electrical signal. A 23-base DNA probe was self-assembled on the gold microelectrode via thiol adsorption. Long-range electron transfer was chosen for the monitoring of the hybridization step. Indeed, this direct transduction was significantly enhanced due to DNA-duplex π-stacking and the use of the redox methylene blue as DNA intercalator5. The electrochemical properties of the sensor were screened with the [Fe(III)(CN)6]3-/[Fe(II)(CN)6]4- redox couple in droplets by using cyclic voltammetry (CV) in a two-electrode configuration which is more adapted in the case of microliter biological samples. Voltammograms centered at potential zero are observed as expected for a working UME and a counter electrode made from the same metal and immersed in the same electrolyte. The 2 mm-gold counter electrode (very high area compared to the 25 μm gold working electrode) can be considered as a pseudo-reference electrode allowing a feeble potential drift during measurements. When working with thiolated SAM absorbed on gold substrates, the matter of desorption is not trivial all the more in chloride electrolytes. The reliability of 10-14 M limit of detection determined for DNA target quantification was deduced from differential current density measured compared with the blank measurements. The data analysis highlights the possible role of the desorption phenomenon of the thiolated DNA probes from the sensor surface that could explained the residual current densities measured for concentrations lower than 10-14M.
1 M. Lazerges and F. Bedioui, Anal. Bioanal. Chem., 2013, 405(11), 3705-3714.
2 J. a. Wilson and S. M. Sagan, Curr. Opin. Virol., 2014, 7, 11–18.
3 S. O. Kelley, E. M. Boon, J. K. Barton, N. M. Jackson and M. G. Hill, 1999, 27, 4830–4837.
4 J. D. Watson and F. H. C. Crick, Nature, 1953, 171, 737–738.
5 M. Lazerges, V. T. Tal, P. Bigey, D. Scherman and F. Bedioui, Sensors Actuators B Chem., 2013, 182, 510–513.

Figure 1
The Investigation of Ti Doped Zinc Oxide Sensing Membrane in Bio-Sensor Applications
Authors: Su Yen Lin 
Published: February 2020

In this study, we propose a highly sensitive electrolyte–insulator–semiconductor (EIS) pH sensor witha layer of novel metal-oxide. We compared the ZnO and Ti-doped ZnO sensing membrane applied in EIS structure and investigated the characteristics of Ti-doped ZnO sensing membrane. Furthermore, we studied the sensing performance of the ZnO and Ti-doped ZnO EIS structure in different (Na+, K+ , Urea, Glucose)solution.
The EIS structures of a ZnO sensing membrane were fabricated on 4-in n-type (100) Si wafers. A 50 nm ZnO film was deposited on theSi substrate by radio frequency reactive sputtering from ZnO and Ti target in the ratio of Ar/O2 = 20/5. Subsequently, samples were annealed in O2ambient for 30 s by RTA at various temperatures from 600, 700, 800. After that, the back-side contact of the Si wafer was deposited by Al film with 300nm-thick. Then, the sensing area was defined by standard photo lithography process using a photo sensitive epoxy, SU8-2005. Finally, the samples were fabricated on the copper lines of PCB by silver gel. Epoxy package was used to separate the EIS structure.
Based on X-ray diffraction and atomic force microscopy data, it is found that Ti doped ZnO sensing membrane has higher surface roughness than the ZnO sensing film. High temperature annealing (700 ◦C) leads to the formation of crystalline oxide thin film with a rough surface. The pH sensing experiments of EIS with Ti doped ZnO membrane annealed at 700 ◦C shows that reference voltage is linearly dependent onsolution pH and an average sensitivity of 57.56 mV/pH. This outstanding pH sensitivity may be attributed to the high surface roughness of oxide membrane. Besides, Ti doped ZnO sensing film has lower drift rate (0.29mV/hr) and hysteresis voltage (2.79mV) than the ZnO sensing film.
To study the urea and glucose sensing property of the ZnO and Ti-doped ZnO on EIS structure, we prepared the solutions of urea and glucose which concentration were controlled in a range from 1mM~32mM and 2mM~8mM. Then, we picked the conditions of ZnO sensing membrane for RTA temperature at 600oC in O2and Ti-doped ZnO sensing membrane for RTA temperature at 700oC. The sensitivity of Ti-doped ZnO in O2ambient has better quality than the ZnO, which sample in urea solution was 3.62mV/mM, the linearity was 87.36%. Besides, sample in glucose solution was 6.42mV/mM, and the linearity was 90.57%.
Finally, we successfully demonstrate the use of Ti doped ZnO EIS structure with uricase-immobilized alginate film for the detection of uric acid in serum. The concentration of serum uric acid measured by EIS biosensor is comparable to that determined by commercial assay kit. This sensitive EIS based biosensorcan potentially be served as the diagnosis tool for general clinical examinations.
Energetically Stable LiMn2O4 Surface Structure and Its Equilibrium Shape
Authors: Kim Soo , Wolverton Chris 
Published: February 2020

Here, we use the density functional theory (DFT) calculations to investigate the (001) and (111) surface structure of the LiMn2O4 (LMO) spinel cathode materials.1 We first test the effect of slab termination, relaxation, and reconstruction, as well as electronic and magnetic ordering for Mn to examine previous discrepancies on the calculated DFT surface energy for LMO in the literature. We reveal that the relative stability of (001) and (111) LMO surfaces significantly vary depending on the relaxation schemes and surface reconstruction. While our initial DFT calculations testing various numerical and physical factors represent a “closed” thermodynamic system at 0 K, in actuality, the system is open to exchange of materials to react with O2 molecule or Li+ ions. Therefore, we further investigate the surface stability of LMO as a function of the oxygen and lithium chemical potentials. Our calculations show that the (001) and (111) DFT surface energies are very close, suggesting the spectrum of cube-like to octahedron-like particles shapes can be observed under different experimental synthesis condition. We predict that higher temperature and high lithium chemical potentials should be avoided to mitigate the Mn dissolution in LMO, where the synthesized LMO particles are likely to contain more (001) surfaces that are more prone to Mn dissolution. In contrast, the (111) surfaces that are composed of Li-rich surface layers could be more resistant to the Mn dissolution.

Reference: [1] S. Kim, M. Aykol, and C. Wolverton, Phys. Rev. B, 2015, 92, 115411.

Acknowledgements: This work was supported by Northwestern-Argonne Institute of Science and Engineering (NAISE).

Figure Caption: Different (001) to (111) surface energy ratio and the corresponding representative LMO particles shapes (as a function of lithium and oxygen chemical potential).

Figure 1
Doping Strategies to Enhance the Na+ Conductivity of the Cubic Na3PS4 Superionic Conductor
Authors: Zhu Zhuoying , Chu Iek-Heng , Deng Zhi , Ong Shyue Ping 
Published: February 2020

Cubic Na3PS4 (c-Na3PS4) is a highly promising sodium superionic conductor solid electrolyte that can enable safer and more energy dense all-solid-state sodium batteries. First reported by Hayashi et al.,1 Na+ conductivities as high as 0.74 mS/cm have been achieved through improvements in synthesis and the addition of suitable dopants. In this work, we report a first-principles investigation of doping strategies to further enhance the Na+ conductivity of c-Na3PS4. We show that pristine c-Na3PS4 is an extremely poor Na ionic conductor, and the introduction of Na+ excess is the key to achieving reasonable Na+ conductivities observed in experiments. Using ab initio molecular dynamics simulations (AIMD), we predict that 6.25% Si-doped c-Na3PS4 has the Na+ conductivity of 1.66 mS/cm, in excellent agreement with previous experiment results (0.74 mS/cm). Remarkably, we find that Sn doping at the same concentration yields a much higher predicted Na+ conductivity of 10.7 mS/cm, though with a slightly higher dopant formation energy. We will also discuss the effect of other dopants and different doping concentrations on the Na+ conductivity. Finally, we will also discuss the role of topology and Na disorder in enabling fast ionic conduction in this material.
References:
[1] Hayashi, A.; Noi, K.; Sakuda, A.; Tatsumisago, M. Superionic Glass-Ceramic Elec- trolytes for Room-temperature Rechargeable Sodium Batteries. Nat. Commun. 2012, 3, 856.