bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution Combustion Synthesis and Rapid Screening of Complex Oxides and Their Composites for Photoelectrochemical Solar Energy Conversion
Authors: Hossain mohammad Kabir , Rajeshwar Krishnan
Published: February 2020

Photoelectrochemical (PEC) water splitting using inorganic semiconductors is an attractive route for renewable energy production. However, many scientific and engineering challenges need to be overcome before its commercialization. Screening of potential semiconductor material candidates falls tops the list. Oxide semiconductors offer many advantages such as stability in a variety of electrolytes, diverse range of bandgaps and their Earth-abundance in nature. In this respect many binary metal oxides have been investigated thoroughly; however, unfortunately, a suitable candidate has not been identified. Hence, ternary and quaternary oxides and their composites have emerged as promising alternatives to binary metal oxides. It is no easy task to screen 8000 ternary and 70000 quaternary combinations and this warrants a
time-efficient
route of synthesis.

Herein, we employed a rapid and energy-efficient method, solution combustion synthesis, to investigate the Cu-Bi-V-O complex system. In this way, we synthesized p-CuBi2O4 and a range of its composites with CuO and α-Bi2O3. As the Cu-V-O system consists of multiple ternary oxide compositions, we were able to synthesize CuV2O6, Cu2V2O7 and Cu3V2O8. Moreover, growth conditions for two polymorphs (low-temperature β-phase and high temperature α-phase) of Cu2V2O7 were identified. Rietveld refinements were performed to confirm phase purity as well as to deduce composition for mixed phases. Finally, the PEC performances of these oxides will be discussed under various electrolyte conditions.
(Invited) Electrochemical Ammonia Synthesis As Potential Alternative to the Haber-Bosch Process
Authors: Soloveichik Grigorii L.
Published: February 2020

The Advanced Research Projects Agency (ARPA-E) funds high risk, high reward transformational research to reduce energy related emissions, reduce imports of energy from foreign sources, improve energy efficiency across all economic sectors, and ensure US technological lead in advanced energy technologies, including aiming sustainable fuels synthesis for energy storage.

Ammonia is considered to be a promising sustainable energy vector with zero carbon emissions in addition to its common use as a fertilizer. Conventional ammonia synthesis via the Haber-Bosch process requires high pressure and temperature that lead to high operational costs. Electrochemical ammonia synthesis via combined electrolysis of dinitrogen and water has a potential for lower energy consumption and simplified process flow. However this route has a fundamental issue of competing hydrogen evolution reaction (HER). Therefore, to realize this potential it necessary to develop electrocatalysts or conditions where HER is suppressed. Another approach combining electrochemical and chemical steps via reaction of lithium metal with N2 followed by protonolysis could provide high faradaic efficiency but consumes more energy.

Recent advances in the development of novel approaches to energy efficient ways to synthesize ammonia via electrochemical route that is being funded by ARPA-E via REFUEL and OPEN 2018 programs will be discussed.
(Invited) Electrochemical Nitrogen Fixation Under Ambient Conditions
Authors: Chen Gaofeng , Ding Liangxin , Luo Raru , Wang Haihui
Published: February 2020

Ammonia is vital to life and industrial manufacture. The traditional technology of ammonia synthesis, Haber-Bosch process, has been plagued for decades with problems of the harsh conditions required (typically 300oC–500oC and 200–300 atm). The mechanism studies of nitrogenase enzymes have recently motivated an alternative electrochemical technology to reduce N2 to NH3 using renewable resources under ambient conditions. Unfortunately, the NRR has seriously subjected to an ultralow Faradaic efficiency and yield rate due to the inert triple bond of N2 molecule and competing hydrogen evolution reaction (HER). This talk will present our strategies focusing on the perspective of catalyst design to tackle challenges of electrochemical nitrogen reduction reaction (NRR), such as proposing a Li+ incorporation strategy to facilitate the N2 activation,[1] recommending a finding of the possibility of efficient NRR catalysts accompanied with vigorous HER,[2] disclosing the significance of sized and spatial effects of two-dimension materials (Ti3C2Tx MXene, black phosphorus) for NRR.[3] Moreover, considering electrochemical NRR as an immature field, rigorous control experiments to eliminate possible contaminations and standard ammonia detection methods to ensure data accuracy are proposed.[4]

References

[1] G. F. Chen, X. Cao, S. Wu, X. Zeng, L. X. Ding*, M. Zhu, H. Wang*, J. Am. Chem. Soc.
2017, 139, 9771-9774.

[2] H. Cheng, L.-X. Ding*, G.-F. Chen, L. Zhang, J. Xue, H. Wang*, Adv. Mater. 2018, 30, 1803694.

[3] Y. Luo, G.-F. Chen, L. Ding, X. Chen, L.-X. Ding*, H, Wang*, Joule
2019, 3, 1-11.

[4] G.-F. Chen, S. Ren, L. Zhang, H. Cheng, Y. Luo, K. Zhu, L.-X. Ding*, H. Wang*, Small Methods
2018, 1800337.
Metal-Organic Framework-Derived Carbon Electrocatalysts for Nitrogen Reduction
Authors: Mukherjee Shreya , Wu Gang
Published: February 2020

Alternatively, electrochemical synthesis of ammonia (ESA) through the nitrogen reduction reaction (NRR) by using renewable electricity has recently attracted significant attention. Herein, we represent our new progress in the development of a new type of carbon electrocatalysts for the NRR, which is derived from a metal-organic framework precursors. The resulting nitrogen and/or metal co-doped carbon are highly disordered, which demonstrated encouraging catalytic activity and stability in both alkaline and acidic electrolytes. In particular, the zinc containing Zeolitic imidazolate frameworks-8 (ZIF-8) derived carbon catalysts exhibit a remarkable production rate of NH3 up to 3.4 × 10−6 mol cm−2 h−1 with a Faradaic efficiency (FE) of 10.2% at −0.3 V vs. RHE under room temperature and ambient pressure using aqueous 0.1 M KOH electrolyte. Increasing the temperature to 60 °C further improves production rates to 7.3 × 10−6 mol cm−2 h−1. The stability of the nitrogen-doped carbon electrocatalyst was demonstrated during an 18-h continuous test with constant production rates. First principles calculations were used to elucidate the possible active sites and reaction pathway. The moiety, which consists of three pyridinic N atoms (N3) adjacent with one carbon vacancy embedded in a carbon layer, is able to strongly adsorb N2 and further realize N≡N triple bond dissociation for the subsequent protonation process. The rate-determining step of the NRR is predicted to be the adsorption and bond activation of N2 molecule. Increasing overpotentials is favorable for the protonation process during NH3 generation. Further doping transition metals such as Fe into the nitrogen-doped carbon likely blocks the N3 active sites and facilitates the hydrogen evolution reaction, a strong competitor to the NRR, thus yielding negative effect on ammonia production.
(Invited) Electrolytic Synthesis of Ammonia at Ambient Conditions from Nitrogen and Acidic Water By a Catalyst-Free, Plasma Process
Authors: Hawtof Ryan , Toth Joseph , Ghosh Souvik , Guarr Evan , Xu Cheyan , Renner Julie N. , Sankaran R. Mohan
Published: February 2020

Industrially, nitrogen reduction to ammonia is performed via the Haber-Bosch process at high pressure and high temperature which makes it difficult to conduct at small scales, and uses hydrogen gas as a reactant that currently comes from steam methane reforming which results in significant carbon dioxide emission. Electrolytic synthesis of ammonia is attractive because it can take place at or near ambient conditions, enables remote operation and integration with renewable sources of energy such as solar and wind, and can rely on water (typically acidic) as the source of hydrogen atoms. However, to date, the selectivity for electrolytic ammonia formation has been low, mostly because of issues associated with the catalyst materials. Specifically, large overpotentials are required to reduce the stable nitrogen molecule, and at these potentials hydrogen preferentially adsorbs on the catalyst surface and leads to hydrogen gas evolution instead of ammonia formation.

In this talk, we will present a new electrolytic approach to ammonia synthesis in which the solid cathode is replaced by a gas discharge (plasma). Similar to the more typical electrochemical systems, ammonia is formed at ambient conditions from nitrogen and water using only electricity. However, nitrogen is reduced without a catalyst by the unique interactions of the plasma and water. Specifically, electrons in the plasma potentially excite or even dissociate the nitrogen molecule in the gas phase, and solvate to produce one of the strongest reducing agents known. Remarkably, we find that at certain processing conditions, ammonia is synthesized with 100% charge-transfer (faradaic) efficiency. Scavenger experiments show that solvated electrons and hydrogen radicals are key intermediates. The dependence of ammonia formation on current, time, and pH, as well as potential reasons for the highly selective synthesis of ammonia in our process will also be discussed.
Surface Modification of Pd Shape-Controlled Nanoparticles for Electrochemical Nitrate Reduction
Authors: Lim Jeonghoon , Park Jinho , Lee Seung Woo , Hatzell Marta C.
Published: February 2020

Nitrate (NO3
-) contamination of surface and ground water is a widespread problem that negatively impacts human health in drinking water. One promising water treatment technology is electrocatalytic denitrification, but the main challenge to this approach is the low activity and selectivity of the NO3
- to nitrogen (N2) process because this conversion results in undesirable products such as nitrite (NO2
-) and ammonium (NH4
+). To achieve an efficient activity and selectivity for the denitrification, here, we modify surfaces of Pd shaped-controlled nanoparticles by using the UPD method. Under the metal desorption area, sweeping stopped at selected potentials can control the surface coverage of metal atoms. We then verify the several redox reactions of the intermediates that result from the reduction of NO3
- to N2 or NH4
+ by conducting RRDE tests. This work demonstrates that modifying the surface of Pd shape-controlled nanoparticles could play an important role as an efficient electrocatalyst for removing NO3
- from water.
(Invited) X-Ray Microscopy of Operating Electrochemical Energy Storage Systems
Authors: Weker Johanna Nelson
Published: February 2020

Hard X-ray transmission X-ray microscopy (TXM) is an ideal tool for in situ and operando studies of functional materials and materials synthesis routes. The high energy X-rays provides relatively relaxed restrictions on in situ environments enabling high resolution 2D microscopy and tomography (3D microscopy)1 across a large range of pressures and temperatures and in varying gas or liquid environments. The full field geometry of TXM allows imaging at the sub-second time scale, allowing relevant dynamics to be captured during; for example, battery cycling,2,3 catalysis reactions,4 electrochemical synthesis,5 and corrosion.6 Moreover, by tuning the incident X-ray energy to specific absorption edges, TXM can capture elemental and chemical (spectro-microscopy) changes at 30 nm resolution within a few minutes (Figure).

Li-ion batteries promise the high specific capacity required to replace the internal combustion engine with a number of possible earth abundant electrode materials; however, setbacks such as capacity fading hinder the full capability of these rechargeable batteries. In the search for better electrode materials, high resolution X-ray microscopy during typical battery operation is vital in understand and overcoming the failure mechanisms of these materials. I will discuss the use of X-ray microscopy including spectro-microscopy and nano-tomography to track electrochemical and morphological changes in the electrode material in real time during typical battery operation.

N. Weker, N. Liu, S. Misra, J. C. Andrews, Y. Cui and M. F. Toney, Energy Environ. Sci.
2014, 7, 2771-2777.

Nelson Weker, Y. Li, R. Shanmugam, W. Lai and W. C. Chueh, ChemElectroChem
2015, 2, 1576-1581.

Nelson Weker, A. M. Wise, K. Lim, B. Shyam and M. F. Toney, Electrochim. Acta
2017, 247, 977-982.

D. Gonzalez-Jimenez, K. Cats, T. Davidian, M. Ruitenbeek, F. Meirer, Y. Liu, J. Nelson, J. C. Andrews, P. Pianetta, F. M. F. de Groot and B. M. Weckhuysen, Angew. Chem. Int. Ed.
2012, 51, 11986-11990.

E. R. Tay, A. E. Goode, J. Nelson Weker, A. A. Cruickshank, S. Heutz, A. E. Porter, M. P. Ryan and M. F. Toney, Nanoscale
2016, 8, 1849-1853.

A. Koronfel, A. E. Goode, J. Nelson Weker, S. E. R. Tay, C. A. Stitt, T. A. Simoes, J. F. W. Mosselmans, P. Quinn, R. Brydson, A. Hart, Michael F. Toney, A. E. Porter and M. P. Ryan accepted to npj Mater. Degrad., 2018, DOI: 10.1038/s41529-018-0029-2.

Figure 1
Bimetallic Nanoparticles Supported on Cr2O3 Microspheres As Heterogeneous Photocatalysts for Light-Induced Alcohol Oxidation
Authors: Belekoukia Meltiani , Tan Jeannie Ziang Yie , Xuan Jin , Vilela Filipe , Garcia Susana , Maroto-Valer Mercedes
Published: February 2020

The development of environmentally benign photocatalytic processes with high reaction rate and high selectivity has always been a significant challenge. Plasmonic metal nanoparticles have been promising light-driven photocatalysts in chemical transformations due to their localized surface plasmon resonance (LSPR). In this study, bimetallic catalysts with various loadings and Ag/Au ratios supported on Cr2O3 microspheres were synthesized and evaluated as heterogeneous photocatalysts for benzyl alcohol oxidation under monochromatic 532 nm laser irradiation. Au and Ag nanoparticles were uniformly decorated on Cr2O3 microspheres by deposition precipitation and wet impregnation method respectively. The optical and physical properties of the as-prepared photocatalysts were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-Ray spectroscopy (EDX), diffuse reflectance spectroscopy (DRS), X-Ray diffraction (XRD) and RAMAN spectroscopy. The bimetallic Ag-Au-Cr2O3 catalysts presented an enhanced photocatalytic activity compared to monometallic catalysts. It should be noted that the enhanced photocatalytic activity was dependent on Ag-Au ratio. Specifically, 0.5 wt.% Ag - 3 wt.% Au /Cr2O3 photocatalyst showed the highest photocatalytic activity, achieving up to 91.2% conversion and 98.5 % selectivity of the targeted benzaldehyde. The remarkable photocatalytic performance over bimetallic nanoparticles can be ascribed to the synergistic effect of Ag-Au alloy nanoparticles under visible light irradiation. Phototelectrochemical tests were performed to further evaluate the role of plasmon mediated charge transfer in the activity of bimetallic nanoparticles.
A Novel Strategy to Synthesize Cathode Heterostructures at the Nanoscale for Solid Oxide Fuel Cells (SOFCs) Using a Molten Salt Solvent
Authors: Levitas Benjamin , Gopalan Srikanth , Kakinuma Katsuyoshi
Published: February 2020

In the last three decades, solid oxide fuel cells (SOFCs) have garnered significant interest for viable alternative energy systems owing to their high electrical efficiency and fuel flexibility. In this work, we introduce a novel synthesis of cathodes in SOFCs. Conventional cathode materials, strontium-doped lanthanum manganite (LSM) and strontium-doped cobalt iron oxide (LSCF), both individually lack the optimal characteristics to maximize oxygen reduction rates. Furthermore, the accumulation of chromium on SOFC cathodes is known to significantly hinder the performance of the cells. Incorporating cathodes with core-shell structures in SOFCs could alleviate this problem: effectively combining the functionalities of both materials and providing a nanoscale protection from Cr poisoning with a shell such as Cr-doped LSM (LSCM), which has been shown to have stable polarization resistances compared to LSM. However, synthesizing core-shell composites previously has proved difficult requiring multiple steps, resulting in non-uniform structures. In this work, we propose a two-step molten salt synthesis process to create core-shell heterostructures with precise composition with relative ease. In doing so, we have synthesized LSM and LSCF using a LiCl-KCl eutectic melt and a LaCrO3-LaMnO3 heterostructure at 550 ºC and dwell times as low as 10 minutes. This result provides a strong motivation to further explore LSCM as a shell for core-shell cathodes to ensure protection from chromium poisoning as well as LSCF-LSM for enhanced cathode functionality. In essence, this work demonstrates an inexpensive, sustainable method to synthesize core-shell cathodes that can potentially provide high power densities and lower rates of degradation arising from Cr-poisoning.
(Invited) Optimizing the Structure and Composition of PFSA/PVDF Fuel Cell Membranes
Authors: Pintauro Peter N. , Wycisk Ryszard , Powers Devon
Published: February 2020

In order to control water uptake and improve the mechanical properties of a highly charged cation or anion exchange membrane, an uncharged polymer is often added to the membrane in one of two ways: (1) the uncharged polymer is added to the membrane casting solution to create a blended polymer film or (2) a composite membrane is made where ionomer is impregnated into a porous uncharged polymer network/support. Improvements in both approaches can be achieved by use of nanofiber electrospinning. Thus, one can electrospin a blended polymer solution of mutually incompatible charged and uncharged polymers, where good shear mixing at the spinneret tip and fast fiber drying minimizes phase separation and where hot-pressing of the resultant fiber mat results in a dense and defect free film. Similarly, dual fiber electrospinning of separate ionomer and uncharged polymer solutions followed by hot pressing/densification circumvents problems associated with impregnating an ionomer solution into a pre-formed reinforcing porous mat. In this talk, three methods of membrane fabrication will be described and contrasted: (1) solution-cast films of a blended polymer solution, (2) membranes from blended electrospun fibers, and (3) membranes from dual fiber electrospun mats. Membranes 20-25 μm in thickness were prepared using a perfluorosulfonic acid (PFSA) ionomer from 3M Co. (660, 725, or 825 EW) and poly(vinylidene fluoride) (PVDF). The effects of membrane composition, i.e., the EW of the PFSA and the PFSA/PVDF weight ratio, and the membrane preparation procedure on proton conductivity, water swelling (gravimetric and in-plane), and membrane mechanical properties will be discussed. In general, it was found that membranes prepared by separately electrospinning PFSA and PVDF exhibited the best combination of high proton conductivity and low in-plane water swelling – two properties relevant to membrane use in a H2/air fuel cell.

Acknowledgement: The authors thank the US DOE (EERE Cooperative Agreement No. DE-EE0006362) for funding this work, as well as Dr. Michael Yandrasits at 3M for providing the PFSA ionomers used in this study.
Nanocomposites of Honeycomb Double Layered MnO2 Nanosheets /Cobalt Doped Hollow Carbon Nanofiber for Application in Supercapacitor and Primary Zinc-Air Battery
Authors: Yang Xiaoxiao , Peng Wei , Fu Kang , Mao Linchang , Jin Junhong , Yang Shenglin , Li Guang
Published: February 2020

A honeycomb double-layered MnO2 nanosheets were successfully deposited on the inner and outer layers of cobalt-doped hollow carbon nanofibers synthesized via the coaxial electrospinning technology (MnO2/Co-HCNFs) by the hydrothermal method. Benefitting from its distinctive hollow structure nanostructure of Co-HCNFs，honeycomb double-layered nanosheets of MnO2 and higher specific surface area of MnO2/Co-HCNFs, MnO2/Co-HCNFs nanocomposites exhibites an enhanced electrochemical property in supercapacitor and zinc-air battery. The as-prepared sample reveals a higher specific capacitance (446 F/g at 0.5 A/g in 1 M Na2SO4 electrolyte). The asymmetric supercapacitor, assembled with the MnO2/Co-HCNFs nanocomposites as positive electrode and KOH-activated porous carbon nanofibers (PCNFs) as negative electrode (MnO2/Co-HCNFs//PCNF), shows a high energy density and a remarkable cycling stability, which implies the practicability for asymmetric capacitors. In addition, the MnO2/Co-HCNFs nanocomposites display preferable oxygen reduction reaction（ORR）catalytic activity (E1/2=0.842V) compared to commercial 20 wt% Pt/C catalyst (E1/2=0.830V) and long-term stability. Notably, a primary zinc-air battery with the MnO2/Co-HCNFs as the cathode catalyst is fabricated and outweighs the Pt/C catalyst in regard to long-term stability and power density.

Figure 1
Synergistic Hybrid MoS2/Fe2O3 Composites for Efficient Hydrogen Evolution in Alkaline Media
Authors: Hu Jue , Zhang Chengxu
Published: February 2020

It is highly desirable to generate H2 by splitting water (2H2O → O2 + 2H2), because the storage of a large amount of energy (4.92 eV) can be realized in the molecular transformation with no emission of greenhouse gases and other pollutants.(1) The hydrogen evolution reaction (HER) is the cathodic half reaction of water splitting, which is the actual process that produces H2 needed to fuel the purported "hydrogen-based economy".(2) HER on earth-abundant molybdenum disulfide (MoS2) in acidic media is a robust process, but it is kinetically retarded in alkaline media. Thus, improving the sluggish kinetics for HER in alkaline media is crucial for advancing the performance of water-alkali electrolyzers. Here, we demonstrate a dramatic enhancement of HER kinetics in base by judiciously hybridizing vertical MoS2 sheets with another earth-abundant material, iron oxide (Fe2O3). The field-emission scanning electron microscopy (FESEM) images in Figure 1a show that the MoS2/Fe2O3 composite is composed of a particle-like structure of Fe2O3 grown closely on the edge surfaces of the vertically aligned MoS2 sheets. The highly ordered lattice planes in the high-resolution TEM (HRTEM) image of MoS2/Fe2O3 composite are clearly visible in Figure 1b. The d-spacing of 0.63 nm and 0.37 nm, which are corresponds to the (002) and (012) facets of MoS2 and Fe2O3 crystals, respectively, suggests the formation of an interface between the (002) facet of MoS2 and the neighboring (012) facet of Fe2O3 in the composite. Benefiting from the desirable structural characteristics, the MoS2/Fe2O3 interfaces synergistically favor the chemisorption of H (on MoS2) and OH (on Fe2O3), and thus can effectively accelerate the water dissociation step and thus the overall HER catalysis. The resultant MoS2/Fe2O3 heterostructures exhibit much better HER performance than bare MoS2 and outstanding stability in base (Figure 1c and d). Our synergistic hybridization of MoS2 with metal oxide materials enlightens the design and fabrication of promising heterostructures for hydrogen evolution in alkaline media.

Figure Caption

Figure 1. (a) High- and (inset) low-magnification FESEM images of MoS2/Fe2O3 composite. (b) P High-magnification TEM image of the MoS2/Fe2O3 composite, showing their interfaces. (c) Polarization curves of the MoS2, Fe2O3 and MoS2/Fe2O3 composite catalysts in 1M KOH solution at a scan rate of 5 mV/s. (d) Chronopotentiometry responses (η ~ t) recorded from MoS2/NiCo-LDH composite at high current densities of -10 mA/cm2.

References

J. L. Dempsey, B. S. Brunschwig, J. R. Winkler, H. B. Gray, Hydrogen evolution catalyzed by cobaloximes. Acc. Chem. Res.
42, 1995-2004 (2009).

J. Hu et al., Hydrogen evolution electrocatalysis with binary-nonmetal transition metal compounds. J. Mater. Chem. A
5, 5995-6012 (2017).

Figure 1
(Invited) Nanoscale Material Design of Zinc Anodes for High Energy Rechargeable Aqueous Batteries
Authors: Liu Nian
Published: February 2020

Zinc metal anode provides 3 times the volumetric capacity of Li metal anode, remains on the same side of separator when discharged to ZnO in basic electrolyte, and is compatible with non-flammable aqueous electrolyte. Indeed, primary zinc-air batteries have long been used for electronic devices requiring extremely high energy density (e.g. hearing aid). However, rechargeable zinc-air batteries have not been successful, limiting their applications in larger markets such as cell phones, laptops, and electric vehicles. In this presentation, I will present our new understanding on the root reasons for Zn anode irreversibility, and our efforts towards making reversible zinc-based batteries using nanoscale material design.
Development and Application of D-Serine Enzymatic Biosensors in Neuroscience Research
Authors: Mauzeroll Janine
Published: February 2020

D-Serine acts as an endogenous co-agonist for N-methyl-d-aspartate receptors at synapses, making it essential for proper brain development and function. This amino acid has also been linked to several neurodegenerative diseases such as Alzheimer’s disease and dementia. Nevertheless, the primary site and mechanism of d-serine release remains unclear. We recently demonstrated the use of an enzymatic amperometric biosensor for the in vivo quantification of endogenous d-serine release in Xenopus laevis tadpoles. In this presentation I will discuss

The effect of the permselective poly(meta-phenylenediamine) electropolymerization conditions on the biosensor’s response time and selectivity,

The use of the D-serine sensor to explore the effect of visual stimulation on D-serine presence and release in Xenopus laevis tadpoles,

The determination of astrocyte release D-serine pathways from primary rodent cells and human stem cells,

The use of Scanning electrochemical microscopy (SECM) to measure localized release of D-serine from a model system.

References:

Polcari D et al.,Localized Detection of d-Serine by using an Enzymatic Amperometric Biosensor and Scanning Electrochemical Microscopy, ChemElectroChem 2017; 4:920-926.

Polcari D et al., Disk-Shaped Amperometric Enzymatic Biosensor for In Vivo Detection of D-serine, Analytical Chemistry 2014; 86(7):3501-3507.

Perry, S.C.; Gateman, S.M.; Sifakis, J.; Pollegioni, L.; Mauzeroll, J. Enhancement of the Enzymatic Biosensor Response through Targeted Surface Roughness. Journal of the Electrochemical Society
2018
, 165(12), G3074-G3079.
A Protonic Biotransducer for Controlling ATP Synthesis in Mitochondria
Authors: Miyake Takeo , Li Chenliang , Ohta Toshiyuki
Published: February 2020

Controlling the flow of ions and electrons at the device/biological interface has become an important challenge in broad fields such as bioelectronics and medical biology. These devices provide a new way to translate bidirectionally between the ionic language of biology and the electronic language of circuitry.

The current strategy to develop such ion and electron controlling devices is to use new functional materials at the device/biological interface. For example, silicon nanowire and carbon nanotube based transistors use ions to read out biological functions. Aluminum nanostraws and carbon nanotube porins can selectively deliver molecules such as cations, DNA, and nicotine into biological materials. Since conductive polymers allow the transport of both ions and electrons, there are many conductive polymer based examples including organic field effect transistors for biosensing and organic ion pumps for locally delivering ions and neurotransmitters into cells and the brain.

Along with ions and small molecules, protons (H+) play an important role in biology. Examples include the homeostatic pH regulation in body and bacteria, acid sensing ion channels activating in neuron cells, proton activated bioluminescence in dinoflagellates, and pH responsive flagella in bacteria. Mitochondria in particular are a noteworthy organelle that utilize the transport of protons and electrons across a membrane to synthesize adenosine triphosphate (ATP) molecules. To translate H+ signals from biological environments into measureable electronic signals, Rolandi and co-workers developed a prototype bioprotonic device using a Pd/PdHx protode. In his group, the metallic protode was used to measure the protonic conductivity in biological materials such as chitosan and jelly from in the ampullae of Lorenzini of sharks, and to integrate electronic signals with an enzymatic flip flop circuit, ion channels, and light-sensitive bacteriorhodopsin. Gorodestky and co-workers have separately demonstrated high proton conductivity in reflectin squid proteins and Pd/PdHx based transistors. All attempts however focused on the interfacing between Pd-based metal and biological materials, even though the Pd protode may occur side reactions such as oxygen conversion (PdO, PdO2 and Pd(OH)x) at the potentials beginning at 0.9 V vs. NHE and toxic hydrogen peroxide production. Here, we develop an organic biotransducer using a high H+-coupling conductive polymer of sulfonated polyaniline (SPA) that monitors and modulates the pH in the vicinity of the SPA electrode, even in solutions with the high buffering capacity typical of mitochondrial environments (Fig.1). We integrate this biotransducer with mitochondria isolated from pig hearts to translate the H+ signal from the activated mitochondria into a measureable protonic current, and also to control the activity of ATP synthase through electrochemical pH modulation at the SPA surface.

Figure 1
Micro Paper-Based Electrochemical Device for Small Molecule Diabetes Biomarkers
Authors: Niroula Jinesh , Premaratne Gayan , Krishnan Sadagopan
Published: February 2020

Glucose monitoring has been widely established as a successful diabetes management system. However, non-glucose markers such as, autoantibodies, hormones, proteins, and other small molecules can provide better assessments for the prediction and management of the disorder. Nevertheless, the challenges our research community faces in designing an analytical device for such markers, especially the small molecules, are the dynamic range, limit of detection, selective isolation of the analyte, higher background noise due to clinical matrix, and ability to transform the system into a cheap point-of-care device. Here, we have designed a paper-based graphene amperometric sensor that can detect a model hormone (insulin, 5808 Da) from complex serum matrix. The paper platform provides for a cheap, on-site filtration system that limits the mobility of larger molecules, and upon combining with a double-blocking step before analyte detection greatly minimizes the background noise. Insulin aptamers acts as a capture probe to selectively identify and bind to insulin. Graphene, coated on working electrode, with its superior electrical conductivity provides for improved analytical features of the detection system. The amperometric signals are achieved by flowing a solution mixture of 1 mM hydroquinone mediator and 0.5 mM H2O2 and applying a constant potential of -0.1 V. The paper-based device exhibits a picomolar limit of detection for serum insulin with a reasonably good dynamic range. Our future prospect is to advance this device further for detecting even smaller molecules (< 500 Da) in complex clinical matrices, for which no current assay methods are available.
Four Probe Impedance and Transference Number Analysis on Polymer Electrolytes in Liquid Phase
Authors: Su Lin-Ya , Wu Nae-Lih
Published: February 2020

To meet the ever increasing demand for high energy density storage devices, not only the high energy density materials are eagerly required, but also is there an increasing attention in achieving a high safety standard for lithium-ion batteries (LIBs). Recently, there have been paper that claimed PVDF coating on the anode is proved to effectively suppress the growth of Li dendrite, leading to high Coulombic efficiency even under large current densities, enhanced full-cell capacity density and improved safety for LIBs. This special coating is named artificial solid-electrolyte interphase (ASEI), which supposed to have the characteristic of flexible and high ionic conductivity.

In order to measure the specific ionic conductivity value of the polymer coating layer, we design a novel four-probe electrochemical impedance spectroscopy (EIS) measuring system, which is allowed to measure the impedance of various polymer membrane in a liquid electrolyte filled atmosphere. With the nature of four probe measurement, the impedance contributed by the electrodes can be ignored in this case, meaning the equivalent circuit is just a resistor, corresponding to the ionic resistance of the electrolyte between the two references. Moreover, the activation energies of each polymer film is also calculated under various temperatures statement applied.

A large transference number can reduce concentration polarization of electrolytes during charge–discharge steps, and thus produce higher power density. It is highly desirable that the transference number of lithium ions approaches 1 in an electrolyte system. In this work, we also set up a complete system to fully analyze the property of various polymers and to further reach to a best polymer for LIBs as an ASEI.

Figure 1
Self-Recovery of Capacity in Lithium Metal Hybrid Lithium Ion Battery
Authors: Pathak Rajesh , Chen Ke , Qiao Qiquan , Zhou Yue
Published: February 2020

Transitional metal oxides (TMOs) are promising anode materials for Lithium Ion Batteries (LIBs) due to their high theoretical capacity. However, due to their low electronic conductivity, poor rate capability and large volume change during charge/discharge processes, still research is in progress to overcome these issues. In this work, we present the first demonstration of a unique self-recovery of capacity in TMOs anode by reducing tungsten trioxide (WO3) incorporating urea, followed by annealing under nitrogen environment. The reduced WO3 successfully self-retained the capacity after undergoing sharp decrease upon cycling. Significantly, the reduced WO3 also exhibited excellent rate capability. The reduced WO3 exhibited a remarkable cycling phenomenon of quick self-recovery of 193.21%, 179.19% and 166.38% at the 15th (521.59/457.41 mAh/g), 36th (538.49/536.61 mAh/g) and 45th (555.39/555.39 mAh/g) cycles respectively compared to their respective preceding discharge capacity. This unique self-recovery phenomenon can be attributed to the synergistic effect of lithium plating and reactivation of oxygen vacancies sites that act as defects which make the WO3 electrode more electrochemically reactive with cycling. The reduced WO3 exhibited notable discharge/charge capacity of 959.1/638.9 mAh/g (1st cycle) and 558.68/550.23 mAh/g (100th cycle) compared to pristine WO3 with discharge/charge capacity of 670.16/403.79 mAh/g (1st cycle) and 236.53/234.39 mAh/g (100th cycle) at a current density of 100 mA/g. Similar technique can be used for other high capacity battery anodes/cathodes to improve their electrochemical reactivity, capacity and stability.

Keywords: Lithium ion battery, tungsten trioxide, urea, lithium plating, oxygen vacancy, capacity self-recovery.
New Forms of Lithium Metal Anode
Authors: Li Sipei , Wang Han , Whitacre Jay , Matyjaszewski Krzysztof
Published: February 2020

A polymer-assisted and solution-processed approach was employed to prepare and extract high-purity lithium metal microparticles (Li MPs) and lithium metal nanoflakes (Li NFs) at gram-scale. Two forms of metallic lithium anode were prepared based on the Li MPs and Li NFs – (1) CNT/lithium solid composite (CLSC) and (2) liquid-like polymer/lithium slurry (LPLS). The CLSC was integrated with commercial carbonate based electrolytes and showed dramatically improved overpotential and stability in both symmetric cell and LFP-based full cell compared to typical lithium foil. The LPLS was paired with ceramic electrolyte Li6.4La3Zr1.4Ta0.6O12(LLZTO) and ran at 1 mA/cm2and 1 mAh/cm2in a symmetric cell for 400 hours with overpotential as low as 150 mV. The facile method of preparing Li micro/nano-structures and the new forms of metallic lithium anodes are of great academic and industrial values.
First Principles Investigation of Grain Boundary Effects in Perovskite-Type Lithium Lanthanum Titanate Solid Electrolyte
Authors: Conlin Patrick Richard , Cho Kyeongjae
Published: February 2020

Lithium lanthanum titanate (LLTO) is considered a particularly promising candidate for use as an electrolyte in all-solid-state lithium ion batteries due its good electrochemical stability and high ionic conductivity. However, measured values for the ionic conductivity of LLTO fall far below theoretical predictions, an incongruity which has been attributed to the presence of grain boundaries. Furthermore, recent experimental work has shown that lithium dendrite growth occurs along the grain boundaries in LLTO. While experimental studies have been able to reveal the detailed microstructure of polycrystalline LLTO, but little effort has been made to identify the fundamental mechanisms at work within the grain boundaries which lead to to suppressed ionic conductivity and Li dendrite growth. Using ab-initio calculations, we examine the electronic character of LLTO grain boundaries and investigate the impact of the defect states on ion transport and dendrite formation. Based on a fundamental understanding of the atomic and electronic character of LLTO grain boundaries, material design approaches are proposed to mitigate the impact of grain boundary behavior and improve the viability of LLTO as a practical solid electrolyte.

This work was supported by the International Energy Joint R&D Program (No. 20168510011350) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Ministry of Knowledge Economy, Korean government. This work is also supported by the L&F Co.’s World Class 300 Project of the Korea Institute of Advancement of Technology (KIAT) funded by the Ministry of Trade, industry and Energy (No.S2483103).
3D Porous Urchin-like NH4V3O8·2H2o Microspheres Constructed for High-Performance and Long-Life Rechargeable Aqueous Zinc Ion Battery
Authors: Lai Jianwei , Xu Wangwang , Wang Ying
Published: February 2020

As one of the promising alternative energy storage systems, aqueous-based rechargeable zinc-ion batteries have received continuous attention owing to their high abundance, cost effectiveness, and high safety. However, the development of suitable cathode materials with superior electrochemical performances are severely hampered by the unstable structural property during Zn2+ intercalation/deintercalation, and the sluggish kinetics of Zn2+ with divalent charge into the host structure. In the present work, a highly reversible aqueous Zn2+ battery is first demonstrated in aqueous electrolyte by employing 3D porous urchin-like NH4V3O8·2H2O microspheres assembled from ultrathin nanowires as cathode materials. Benefiting from the synthetic merits of the unique 3D porous architecture, it can provide numerous accessible channels for fast kinetics of Zn2+, short diffusion path for Zn2+ migration, and promote the rapid transfer of electrons. As a result, the NH4V3O8·2H2O microspheres cathode exhibits excellent electrochemical performances with a high reversible capacity of 415 mAh g-1 at 0.2 A g-1, superior rate capability, and durable cycling stability with a capacity retention of 80% after 2000 cycles under the high current density of 10 A g-1. Our result demonstrates that such porous NH4V3O8·2H2O microspheres cathode material is a potential candidate for the high performance rechargeable aqueous zinc-ion battery. Furthermore, the quasi-solid-state NH4V3O8·2H2O/Zn battery shows high potential for flexible energy storage systems.
Failure Analysis of the Rechargeable Porous Zinc Electrode in Alkaline Electrolyte
Authors: D'Ambrose Michael Joseph , Yadav Gautam Ganapati , Turney Damon , Gallaway Joshua W. , Nyce Michael , Messinger Robert J. , Banerjee Sanjoy
Published: February 2020

Metallic zinc (Zn) is an attractive negative electrode material for rechargeable batteries because it is a non-toxic, earth abundant metal. It has a low equilibrium potential of -1.35 V vs. mercury-mercuric oxide (Hg|HgO) in concentrated alkaline electrolyte, a high gravimetric discharge capacity of 820 mAh/g, and a high volumetric discharge capacity of 5850 mAh/mL. During discharge, Zn oxidizes and forms a dissolved complex known as the zincate ion, Zn(OH)4
2-, from which zinc oxide (ZnO) precipitates as a solid. On charge, Zn(OH)4
2- is reduced to metallic Zn. Motivation to study the Zn electrode in rechargeable batteries is driven by a target overall battery energy density of 200 Wh/L that is sustainable for 500 or more charge-discharge cycles. This corresponds to a Zn electrode volumetric capacity of 650 mAh/mL.

The cycle life of the porous Zn electrode in concentrated alkaline electrolyte is observed to decrease with increasing percentage of discharge capacity of Zn accessed. The percentage of discharge capacity of Zn accessed is known as the depth of discharge (DOD). Zn electrodes were cycled in the range of 1% to 15% Zn DOD in zinc-manganese dioxide (Zn-MnO2) batteries and in the range of 15% to 30% Zn DOD for zinc-nickel (Zn-Ni) batteries. Additives were incorporated into the zinc electrodes for the tests done on Zn-Ni batteries. Additives used were surfactant cetyltrimethylammonium bromide (CTAB), bismuth oxide (Bi2O3), synthetic layered silicate Laponite, and calcium hydroxide (Ca(OH)2). The potential values of the Zn electrodes vs. Hg|HgO reference electrodes were recorded.

During healthy galvanostatic discharge, Zn electrodes displayed a nearly constant potential vs. Hg|HgO at approximately -1.35 V. Tests that failed due to Zn exhibited a shift from this equilibrium potential that corresponded to a loss of cell voltage. This shift may be attributed to a concentration overpotential as ZnO is precipitated, thereby inhibiting the hydroxide ions from reaching the reacting metal interface. The shift may also be due to formation of a passivated layer on the electrode which effectively blocks the remaining active material. There are multiple regimes observed in the potential curves of the Zn electrode vs. Hg|HgO prior to cell failure. Beyond the healthy plateau at -1.35 V, a sloping potential is observed. This is followed by an additional plateau. The second plateau shifts with increasing cycle number and precedes cell death. See the attached figure for discharge curves of a Zn electrode cycled at 11.3% Zn DOD. After the second plateau a steep slope is observed in the potential for later cycles, which is believed to be due to passivation of the Zn electrode. The additives were observed to modify the discharge potential curve of the Zn electrode vs. Hg|HgO.

Figure 1
Strain-Induced Ionic Conductivity of Cubic Li6.25Al0.25La3Zr2O12 solid Electrolyte
Authors: Moradabadi Ashkan , Kaghazchi Payam
Published: February 2020

Al-doped cubic-Li7La3Zr2O12 (Al-LLZO) is a promising solid electrolyte material for all-solid-state batteries (ASSB). Nevertheless, ionic conductivity of Al-LLZO is rather poor in its bulk structure and also at the electrolyte/electrode interfaces due to high resistivity. By means of lattice-mismatch induced strain, rate performance of battery materials such as solid electrolytes can be enhanced. In this contribution, thermodynamics (concentration) and kinetics (mobility) of defects as charge carriers in Al-LLZO using DFT calculations and ab initio molecular dynamics simulations will be discussed. In addition, the influence of strain on the diffusion mechanism and conductivity of the dominant defect in bulk Al-LLZO will be addressed. Furthermore, by comparing PBE and HSE06 results, the effect of exchange and correlation functionals on the stability and defect chemistry in Al-LLZO will be presented. The findings of our study can be employed to explore the strain effects for promoting the rate capability of ASSB.
(Invited) Photo-Electrode Hybrid Materials Based on Metal-Oxide and Pi-Conjugated Units for Solar-Energy Conversion Devices
Authors: Santoni Marie-Pierre , Jouini Mohamed , Delices Annette , Xu Zijun , Dong Chang-Zhi , Bellynck Sebastien , Rutkowska Iwona Agnieszka , Kulesza Pawel J.
Published: February 2020

Multi-component inorganic-organic hybrids are tunable units used to build-up mesoscopic architectures / devices for various applications. We focus our interest on hybrid materials for the elaboration of photoelectrodes to be integrated into solar-energy conversion devices, such as solid-state Dye-sensitized Solar Cells (ss-DSCs, for photovoltaic conversion) and Dye-sensitized PhotoElectrosynthesis Cells (DSPECs, for photocatalytic conversion to “Solar Fuels”).

In order to improve charge transfers and transport within photoelectrodes, along with overall stability and efficiency, we use controlled-deposition electrochemical techniques (for example, in situ electro-assisted PhotoElectroPolymerization (PEP)) for the preparation of the Hole-Transporting Material (HTM, used as a charge carrier within the device) on the photosensitized mesoporous semi-conductor of the electrode. This allows a better filling of mesoporous materials and a better contact between the components of the hybrid material/electrode.[i] We also remove the physical interface between components (for example, between Dye/HTM) by introducing a covalent bond between components (molecular engineering of bifunctional conjugates).[ii]

We will present our recent progress on NiO-based p-type photocathodes for low-temperature CO2 reduction, based on electrocatalytic and photoelectrochemical approaches.

[i] Zhang, J. et al. Nano Energy,
2016, 19, 455-470.

[ii] A. Delices et al.
Electrochim. Acta,
2018, 269, 163-171.

Figure 1
Understanding the Highly Selective Electroreduction of Carbon Dioxide into Fuels on Hierarchical Oxide-Derived Inverse Opals
Authors: Nguyen-Phan Thuy-Duong , Kauffman Douglas R. , Zhou Yunyun , Yu Yang , Stavitski Eli , Xu Wenqian , Howard Bret H. , Stuckman Mengling Y. , Waluyo Iradwikanari , Wang Congjun , Marin Christopher M. , Popczun Eric J. , Ohodnicki Paul R
Published: February 2020

The production of value-added chemicals and fuels from CO2 and water by highly efficient, selective, robust electrocatalytic materials is of vital interest to address the energy challenges. In this work, we report a hierarchical CuO-derived inverse opal (CuO-HIO) electrocatalyst which demonstrated impressive CO selectivity and negligible H2 evolution at high current densities (achieved ~35 mA cm-2 at -1.2 V vs. RHE). Such a three-dimensional interconnected porous network with voids about 200 nm surprisingly exhibited a Faradaic efficiency (FE) of 72.5% for CO production at -0.6 V vs. RHE and was very stable during 24-hour CO2 electrolysis. The in situ Cu K-edge XANES and Fourier transformed EXAFS spectra dynamically revealed the direct transformation of Cu2+ to Cu0 species within few minutes at -0.6 V vs. RHE and CuO was entirely reduced to metallic copper after 60 min. Such an observation was well consistent with the in situ time-resolved XRD patterns which illustrated the gradual emergence of (111), (200), (220), (311), and (222) diffractions of cubic copper under the working condition. CO2-to-CO outperformance of CuO-HIO catalyst over typical oxidized copper catalysts could be ascribed to (i) the mass transport limitation and local pH effect induced by unique hierarchical morphology, (ii) highly roughened surface, and (iii) in situ reduction of Cu2+ to stabilized metallic Cu active sites during the CO2 electrolysis. Our findings may open an opportunity for rational design of promising, high-performance, less expensive electrocatalysts for renewable fuel production from fossil fuel-generated CO2 emission.