bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Doping Effects on the Co Oxides for the Water Oxidation
Authors: Kim Byunghoon , Park Inchul , Kang Kisuk 
Published: February 2020

Electrochemical water splitting provides sustainable means of generating hydrogen fuel, a carbon-free alternative for fossil fuels. The bottleneck in proceeding water splitting reaction is the sluggish kinetics of the oxygen evolution reaction (OER), resulted from its complex four-electron pathway. While precious metal oxide-based materials such as IrO2 and RuO2 deliver superior catalytic activity toward OER, their scarcity and high cost is not appropriate for the large-scale commercialization. In this respect, earth-abundant, first-row (3d) transition metal oxides have been of recent interest.1 As an effective strategy to enhance the activity of 3d metal based catalysts, great efforts have been dedicated to multi-metal systems. Exploiting large diversity of metal compositions, various multi-metal oxides-based catalysts have been reported, including Ni-Fe, Co-Fe, Ni-Co, and ternary oxides/oxyhydroxides.2 Among them, Fe-containing Co and Ni based oxide-based catalysts have known to be most active toward OER in alkaline electrolyte.3 Despite the substantial research efforts to unveil the origin of improved activity of Fe-containing Co and Ni oxide-based catalysts, one of the most important task that still remains unsolved is the accurate determination of catalytic active sites and their reaction mechanism at the atomistic scale.
In this work, we present a theoretical study on the electrocatalytic properties of pristine and transition metal (Fe, Ni, and Mn)-substituted Co oxides. Through the exhaustive consideration of oxygen sites in the vicinity of dopants, the prediction of the active sites and reaction mechanism is provided. The OER mechanisms estimated for the terminal sites of dopant and neighboring Co cations, and for the bridge site are introduced in detail. Notably, it is demonstrated that the bridge site which has been generally considered inactive for OER can be activated by Fe incorporation. We further investigate the structural properties of the relevant intermediates. With the structural analyses, we propose that the modulation of hydrogen bonding distance induced by the Jahn-teller active Fe(IV) cation leads to the activation of the bridge site. Finally, with the comprehensive view of estimated OER thermodynamics, we suggest an origin of improved OER performance of the Fe-containing Co oxide-based catalysts. We believe that our findings establish theoretical deign rule of Co based multi-metal oxide-based catalysts, and propose a viable strategy to resuscitate catalytic activity of inert sites by the structural modulation through cation doping.

Reference

P. et al. Energy Environ. Sci. 5, 6012 (2012).

N.T. et al. Chem. Soc. Rev.
46, 337 (2017).

C.L. et al. J. Am. Chem. Soc.
137, 4347 (2015).
Enhanced Perovskite Electrocatalysis By Cation Deficiency and Strain Control
Authors: Choi Min-Ju , Jang Ho Won 
Published: February 2020

Increasing energy demand, fossil fuel depletion, and environmental issues require sustainable and efficient energy sources. Hydrogen produced by water splitting is one of the promissing candidates, and electrocatalysts can help to reduce overpotential of the reaction. Electrocatalytic activity can be improved by increasing number of active sites and intrinsic activity. Tuning cation deficiency and strain can enhance intrinsic activity. Here, we explore how cation deficiency and strain can affect electrocatalysis.
Noble metals are representative electrocatalysts, but they are expensive and unstable during oxygen evolution reaction (OER) in alkaline solution. Therefore, new materials for water splitting such as transition metal oxides are needed. Perovskite oxides have been actively studied because of their excellent catalytic activity, attractive physical-chemical properties, low cost, and non-toxicity.
To investigate the effect of La-site deficiency, epitaxial La1-xNiO3-δ (x=0, 0.05, 0.1, 0.15) thin films were deposited on NdGaO3 substrates by pulsed laser deposition (PLD) method. The structural information of each film was verified by X-ray diffraction peaks in θ-2θ scans, Raman spectroscopy and X-ray linear dichroism (XAD) measurements. Each of La-site deficient samples were electrochemically characterized. To compare the effect of La-site deficiency and strain, which can induce eg orbital polarization, an epitaxial La0.95NiO3-δ thin films were grown on a different lattice parameter substrates ranging in lattice parameter from 3.69 to 3.947 Å. They were also characterized physically and electrochemically. Based on experimental results, cation deficiency and strain can cause the eg orbital polarization. Both can control the metal-oxygen bond strenth and improve catalytic activity.
Anodized Hematite Nanostructures and Their Electrochemical Properties for Photoelectrochemical Water Splitting
Authors: Rosas-Barrera Kevin Leandro , Pedraza Julio Andrés , Reguera Edilso , Acevedo-Peña Prospero 
Published: February 2020

Photoelectrochemical (PEC) water splitting using semiconductor electrodes has received much attention in the last decades. In this sense, hematite photoanode has appeared as a good candidate due to it is synthetized from cheap and abundant elements, non-toxicity and has a band gap of 2.1 eV that permits the absorption of visible light (Sivula, Le Formal, & Grätzel, 2011). However, their transport properties change drastically depending of synthesis method employed and the different morphologies obtained (Horiz et al., 2016). In this study, we report the electrochemical growth of hematite (α-Fe2O3) nanostructures by anodization process of carbon steel substrates in an ethylene glycol based medium. The influence of experimental parameters including the NH4F concentration, anodization time and applied voltage were systematically investigated to study their electrochemical properties. The obtained films were heat treated to 500 ºC to obtain the hematite crystalline phase. The crystalline phase was determined using an X-ray diffraction and Raman spectroscopy. FE-SEM images of the hematite nanostructures films provided morphological parameters. Photoelectrochemical characterization was achieved through OCP, LSV, CA and EIS procedures. A hard dependence between the synthesis variables and their photoelectrochemical properties for water splitting reaction was observed.
Horiz, N., Tamirat, A. G., Rick, J., Dubale, A. A., Su, W.-N., & Hwang, B.-J. (2016). Using hematite for photoelectrochemical water splitting: a review of current progress and challenges. Nanoscale Horizons, 1, 243–267. https://doi.org/10.1039/c5nh00098j
Sivula, K., Le Formal, F., & Grätzel, M. (2011). Solar water splitting: Progress using hematite (α-Fe2O3) photoelectrodes. ChemSusChem, 4(4), 432–449. https://doi.org/10.1002/cssc.201000416
Metal-Free Dyes Based on Piperidine-Substituted Perylene-Monoanhydride Derivatives As Sensitizers in ZnO-Based DSSCs
Authors: Canto Aguilar Esdras Josué , Guitiérrez Moreno David , Sastre-Santos Ángela , Fernández-Lázaro Fernando , Mori Shogo , Oskam Gerko 
Published: February 2020

The dye sensitized solar cell (DSSC) is a third generation photovoltaic technology with conversion efficiencies as high as 14 %, which has been achieved through the optimization of the cell components and a better understanding of the mechanisms of charge generation and recombination processes involved in the solar cell functioning. The selection of the most promising components (e.g., the film material, the dye and the redox couple) related with their single properties is the starting point in the efficiency improvement process. Based on this observation, ZnO is one of the most promising alternatives to replace TiO2 as electron transporting material in the DSSCs, this due to its higher electron mobility (comparing with TiO2), where the ZnO-organic dyes combination promises an increase in the overall efficiency of the solar device.
Poor chemical stability of ZnO (compared to TiO2) during the sensitization process has been reported as an important efficiency-limiting factor in ZnO-based DSSCs, related to the "acidic" character of the groups through which the molecule binds to the surface of the material. Piperidine-substituted perylene-monoanhydride derivatives not only show light absorption in a wide range of the electromagnetic spectra and high molar extinction coefficients, making them attractive molecular absorbers for this application, but also show to be a factible route to overcome the stability issue associated to the ZnO, anchoring the molecule at the semiconductor surface through the rupture of the anhydride moiety. In this work we study the suitability of sensitizers based on piperidine-substituted perylene-monoanhydride derivatives to interact with ZnO (evaluating their ability to show "aggregation"), and their performance in photovoltaic devices related to the optical and energetic features of these molecules, determined by spectroscopic and electrochemical techniques.
Photocatalytic Oxigen Production Using Nitroprussides Derived Materials
Authors: Diaz Lujan Alfredo , Reguera Edilso , Acevedo-Peña Prospero 
Published: February 2020

Energy and environmental concerns related to the use of fossil fuels have forced researchers to seek renewable and clean energy resources. The demand of this energy encourages to study artificial photosynthesis, in which high-energy compounds are produced from water as an electron donor, by utilizing solar energy [1,2,5]. In a quest to develop sustainable energy conversion processes, many research groups have attempted water splitting using sunlight, which occurs in two processes: water oxidation or oxygen evolution reaction (OER) and water reduction or hydrogen evolution reaction (HER). However, oxidation of water to produce O2 is challenging from both thermodynamic and kinetic points of view, and thus, this process is considered too important for water splitting [3,4]. It is important to study the catalytic activity of different catalysts, especially when using sustainable and cheaper semiconductors for the oxidation of photoactivated water.
This work presents the synthesis, characterization of catalysts derived from nitroprussides as new materials for photocatalytic for oxygen evolution reaction [5]. Our attempts to use electrocatalysts derived from Nitroprussides (Np) M[Fe(CN)5NO] where M = Fe2+, Mn2+, Co2+ and Ni2+, in photocatalytic water oxidation (pH 7.2) using [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) as a sensitizer and Na2S2O8 as an electron acceptor [2], will be discussed in this presentation.

References:

[1] Mohammad Mahdi Najafpour, Spideh Madadkhani, Mojtaba Tavahodi, Manganese oxides supported on nano-sized metal oxides as water-oxidizing catalysts for water-splithing systems: 3-Electrochemical studies, International Journal of Hydrogen Energy 42 (2017) 60-67.
[2] Yusuke Yamada, Kohei Oyama, Rachel Gates, and Shunichi Fukuzumi. High Catalytic Activity of Heteropolynuclear Cyanide Complexes Containing Cobalt and Platinum Ions: Visible-Light Driven Water Oxidation. Angew. Chem. Int. Ed. 2015, 54, 5613 –5617.
[3] Mingxing Chen, Yizhen Wu, Yongzhen Han, Xiaohuan Lin, Junliang Sun, Wei Zhang and Rui Cao. An Iron-based Film for Highly Efficient Electrocatalytic Oxygen Evolution from Neutral Aqueous Solution. ACS Appl. Mater. Interfaces 2015, 7, 21852−21859.
[4] Sara Goberna-Ferroń, WillintonY.Hernańdez, BarbaraRodríguez-García, and José Ramoń Galań-Mascaroś. Light-Driven Water Oxidation with Metal Hexacyanometallate Heterogeneous Catalysts. ACS Catal. 2014, 4, 1637−1641.
[5] L. Reguera, J. Balmaseda, C.P. Krap, and E. Reguera, Hydrogen Storage in Porous Transition Metals Nitroprussides, J. Phys. Chem. C2008, 112, 10490-10501.
(Invited) Design of Nanomaterial-Based Electrochemical Sensor for Sensitive Detection of Nitric Oxide
Authors: Chen Aicheng , Liu Zhonggang , Khaper Neelam 
Published: February 2020

Nitric oxide (NO) plays important roles in myriad biological processes and is considered as a biomarker of cardiovascular disease, hypertension, symptoms of vaginitis, and cancer. Sensitive detection of NO molecules is vital toward the understanding of cell functionality and pathology as well as to the diagnosis of disease, drug discovery, and biological research [1-4]. Here, we report on the development of high-performance NO electrochemical sensors based on the nanocomposite of reduced graphene oxide (rGO) and AuPt bimetallic nanoparticles (rGO-AuPt) and the nanoporous Au microelectrode.
The rGO-AuPt nanocomposites were formed a glassy carbon electrode (GCE) using an electrochemical method. The prepared nanocomposites were tested for the electrochemical detection of NO using differential pulse voltammetry (DPV) and amperometric methods. The dependence of AuPt molar ratios on the electrochemical performance was investigated. Through the combination of the advantages of the high conductivity from rGO and highly electrocatalytic activity from AuPt bimetallic nanoparticles, the rGO-AuPt based NO sensor exhibited a high sensitivity of 7.35 µA µM-1 and a low detection limit of 2.88 nM. Additionally, negligible interference from common ions or organic molecules was observed, and the r-GO-AuPt modified electrode demonstrated excellent stability. Moreover, this optimized electrochemical sensor was practicable for efficiently monitoring the NO released from rat cardiac cells, which were stimulated by L-arginine (L-arg), showing that stressed cells generated over 10 times more NO than normal cells.
The nanoporous gold microelectrode was fabricated via an electrochemical alloying/dealloying method. It exhibited a high electrochemically active surface area and excellent performance for the detection of NO with high stability. Based on DPV and amperometric techniques, extremely high sensitivities (21.9 μA μM-1 cm-2 and 14.3 μA μM-1 cm-2) with very low detection limits of 17.0 nM and 1.43 nM, respectively, have been achieved. Moreover, the developed nanoporous Au microelectrode provides a new approach to monitor NO release from different cells, revealing that a significant differential amount of NO can be generated from the normal and stressed rat cardiac cells as well as from the untreated and treated breast cancer cells, promising for the elucidation of cellular stress responses and medical diagnostics.

References

[1] Z.G. Liu, H. Forsyth, N.Khaper, A. Chen. Analyst 141 (2016) 4074-4083.
[2] M. Govindhan, A. Chen. Microchim. Acta 183 (2016) 2879-2887
[3] M. Govindhan, Z. Liu, A. Chen. Nanomater. 6 (2016) 211.
[4] Z Liu, A Nemec-Bakk, N Khaper, A Chen. Anal. Chem. 89 (2017) 8036-8043
Honeycomb Support Structures to Stabilize PMMA Mold during LIGA Processing of High Aspect Ratio Gratings for XPCI Systems
Authors: Baca Kalin R , Arrington Christian L. , Hollowell Andrew E , Finnegan Patrick Sean , St. John Christopher R. , Pillars Jamin R. , Dagel Amber L , Singh Varshni 
Published: February 2020

X-ray phase contrast imaging (XPCI) allows for medical and non-destructive testing of soft tissue [1]. High aspect ratio (HAR) gratings (100:1) are difficult to achieve and are a key element of XPCI gold gratings PMMA lithography, molding, and electroforming (LIGA) process [2]. Development of uniform, continuous HAR gold gratings over a large area is difficult as they easily tilt and delaminate. One technique for stabilizing the mold during development is to incorporate relief structures into mold, providing more surface area at the bottom, which results in segmented gratings [2]. In the current work, honeycomb supports are used to stabilize the PMMA mold during development and plating to realize continuous gratings centimeters in lateral length. Our goal is to fabricate micron size HAR gratings ~10 cm in lateral length that are ideal for XPCI applications enabling larger field of view for the XPCI imaging.
Honeycomb structures were patterned on a 100 mm substrate. A sheet of PMMA is then bonded and fly cut to desired height. An x-ray exposure then patterns the PMMA mold prior to the fabrication of the top honeycomb structure. The gratings are then developed and electroplated having structural support on both sides. The use of bottom and top honeycomb arrays provide unique mechanical support to the fragile PMMA mold during development and electroplating of the HAR grating.

Momose, A. and W. Yashiro, X-ray Phase Measurements with Talbot Interferometry and Its Applications. International Conference on Advanced Phase Measurement Methods in Optics an Imaging, 2010. 1236: p. 195-199.

Mohr, J., et al., High Aspect Ratio Gratings for X-Ray Phase Contrast Imaging. International Workshop on X-Ray and Neutron Phase Imaging with Gratings, 2012. 1466: p. 41-50.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Figure 1: Schematic of mold stabilization design (left), honeycomb pattern (right)

Figure 1
Advanced Anion Conducting Multiblock Copolymer Membranes with Hydrocarbon Backbones
Authors: Huang Garrett , Mandal Mrinmay , Liu Lisha , Kohl Paul A 
Published: February 2020

While research and development has been focused primarily on proton exchange membrane (PEM) devices in recent decades, devices based on anion exchange membranes (AEM) have garnered increased interest as a potential cost-saving alternative. To be viable for use in electrochemical devices, AEMs must have good long-term alkaline and thermal stability, high hydroxide ion conductivity, lower water uptake, high molecular weight, and low oxygen or fuel permeability.
Polar groups in the polymer backbone are susceptible to nucelophilic attack by the hydroxide ion, which is a major concern for the long-term stability of these materials. In the past, AEMs containing aryl ether bonds degraded under alkaline conditions. Alternatively, materials with a fully hydrocarbon polymer backbone have been shown to provide a route to low-cost and chemically resilient AEMs.
In this study, several new classes of AEMs with fully hydrocarbon backbones were synthesized and characterized. Multiblock copolymers with tethered quaternary ammonium conducting groups were chosen to promote phase segregation and enhance the ionic conductivity. The AEMs were made from vinyl addition and ring-opening metathesis polymerization (ROMP) of norbornenes. These results were compared to a previous study involving AEMs made from partially fluorinated poly(arylene ether)s. The mechanical and thermal stability, ionic conductivity, long-term alkaline stability of all classes of polymers are discussed in detail in the context of performance in an AEM fuel cell or electrolyzer.

Figure 1
Study of the Protein Bovine Serum Albumin (BSA) and the Triblock Copolymer P103 Interface By Differential Capacitance
Authors: Soltero Martinez J. Félix Armando , Velasco Brenda , Larios-Duran Erika Roxana , Rosales Rivera Luis Carlos 
Published: February 2020

Triblock copolymers are considered as non-ionic surfactants due to their self-assembling nature. Triblock copolymers can form structures similar to micelles and larger structures at a certain concentration and temperature. The triblock copolymers used here are biodegradable, water-soluble and are formed by chains of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), which can be arranged as A-B-A or B-A-B; where A are chains of PEO and B chains of PPO. And in this case they are referred by the commercial name Pluronics. The physicochemical properties of these surfactants (Critical micellar temperature (CMT), critical micellar concentration (CMC), density, molecular weight, etc.) depend on their molecular weight, the number of PPO and PEO chains present in the triblock copolymer, on the solvent (polar or no polar) and on the presence of salts in the solution.
Applications of triblock copolymers are diverse; for instance, in the field of biotechnology they have been used for the controlled release of drugs, proteins, DNA. However, even when these compounds are already used and applied in several topics, there is a lack in the knowledge concerning to the effect of the interactions of them with other compounds, such as biopolymers. The main interest is to understand the effects of these interactions in the characteristic shape or size of aggregates formed by triblock copolymers. In order to obtain information about this topic, an initial approach is to study the interactions of some triblock copolymer and some well-characterized protein, as bovine serum albumin (BSA). BSA protein is cheap, easy to isolate and purify. In this way, BSA is an excellent option for the interactions study that exist between proteins and triblock copolymers.
The objective of this work is to contribute to the knowledge of the interactions of triblock copolymers and proteins through the use of electrochemical techniques to obtain information about the amount of species adsorbed on the electrodes, as well as the size of the interface formed by the interaction of both, protein and triblock copolymers, once they are adsorbed on a metal surface. This information is important in the design of the sensors and is also necessary for the application of drug delibery and other fields of bioengineering and biomedicine.
Thus, this investigation is focused on the interaction between BSA and the termosensible triblock copolymer Pluronic® P103 (PEO17-PPO60-PEO17). The interactions are studied by the adsorption of both compounds onto a gold disk electrode immersed in a phosphate buffer solution. Some electrochemical techniques, such as cyclic voltammetry and Differential-capacitance vs. Polarization potential are presented and analyzed in a wide range of temperatures and different P103 and BSA concentration. The thickness of the interface and the effect on the polarization potential are reported.