bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Alloy of Platinum with Rare Earth Metals for High Oxygen Reduction Reaction Activity and Durability
Authors: Campos-Roldán Carlos Augusto , Parnière Alice , Donzel Nicolas , Pailloux Frédéric , Blanchard Pierre-Yves , Jones Deborah J. , Rozière Jacques , Cavaliere Sara 
Published: July 2022

In the search for highly active and durable electrocatalysts for the oxygen reduction reaction (ORR), alloys of Pt with rare-earth metals (REM) have been demonstrated as one of the most promising candidates. However, their synthesis by conventional chemical methods is challenging, since REM have very low reduction potentials and high oxygen affinity leading to the formation of oxides rather than alloys.
We prepared a series of carbon supported Pt-REM nanomaterials with a solid-state method[1], characterized by physico-chemical techniques and evaluated towards the ORR in acidic medium.
The influence of the type of rare earth metal, of the Pt:REM ratio[2], of the post-synthesis treatment[3], and of the nature of the carbon support on the structural, morphological and electrochemical properties of the prepared electrocatalysts was investigated.
In this presentation we will give an overview of the results obtained on these highly active and durable carbon-supported Pt-REM nanostructured electrocatalysts and of the challenges to be tackled for their application at the cathode of proton exchange membrane fuel cells.
[1] Y. Hu, J.O. Jensen, L.N. Cleemann, B.A. Brandes, Q. Li, Synthesis of Pt–Rare Earth Metal Nanoalloys, J. Am. Chem. Soc. 142 (2020) 953–961.
[2] C.A. Campos-Roldán, F. Pailloux, P.-Y. Blanchard, D.J. Jones, J. Rozière, S. Cavaliere, Rational Design of Carbon-Supported Platinum–Gadolinium Nanoalloys for Oxygen Reduction Reaction, ACS Catal. 11 (2021) 13519–13529.
[3] C.A. Campos Roldán, F. Pailloux, P.-Y. Blanchard, D.J. Jones, J. Rozière, S. Cavaliere, Enhancing the Activity and Stability of Carbon-Supported Platinum-Gadolinium Nanoalloys towards the Oxygen Reduction Reaction, Nanoscale Adv. (2021). doi:10.1039/D1NA00740H.
(Invited) Mapping Electrochemical Strain in Platinum Nanoparticles Via Bragg Coherent Diffraction Imaging
Authors: Atlan Clément , Richard Marie-Ingrid , Martens Isaac , Dupraz Maxime , Chatelier Corentin , Viola Arnaud , Leake Steven , Maillard Frederic 
Published: July 2022

Variations in the interatomic distances lead to altered d-band centre for a given metal, and provide an elegant way to control its activity towards (electro)catalytic reactions (“strain-engineering” approach). The effect of strain was rationalized within the frame of the d-band theory of Hammer and Nørskov in the late 1990s [1,2]. The authors predicted that the rate of the sluggish oxygen reduction reaction (ORR) can be enhanced on catalysts binding *OH ca. 0.10 - 0.15 eV more weakly than Pt(111), [1, 2] and this prediction was experimentally verified using a Pt3Ni(111)-skin surface.[3] Nevertheless, these predictions hardly translated to nanomaterials, because of the wide variety of catalytic sites configurations. Also, the d-band theory mostly considers catalytic surfaces in vacuum, without any effect related to the electrical double layer and adsorption/desorption processes. Hence, an in situ picture of how strain develops on Pt-based surfaces is still lacking.
In this contribution, we took benefit of recent advances in Bragg Coherent Diffraction Imaging (BCDI) [4, 5]and of the fourth generation Extremely Brilliant Source of the European Synchrotron (ESRF-EBS, Grenoble, France) to map strain over Pt nanoparticles in situ. Our results show that adsorption of anions causes appearance of compressive strain at under-coordinated (edges and corners) atoms and tensile strain at highly-coordinated ({001} and {111} facets) atoms. Strain heterogeneity increases with the electrode potential and reaches as large as 0.08 %. at ORR-relevant potential. These results provide direct insights into the dynamics of Pt nanoparticles in an electrochemical environment, and have direct consequences for electrocatalysis in general, and for ORR electrocatalysis in particular.

Ackowledgements

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant n° 818823). FM acknowledges the financial support from the French National Research Agency in the frame of the BRIDGE project (grant n° ANR-19-ENER-0008-01).

References

[1] B. Hammer, J. K. Nørskov, Surf. Sci. 1995, 343, 211.
[2] B. Hammer, Y. Morikawa, J. K. Nørskov, Phys. Rev. Lett. 1996, 76, 2141.
[3] V. R. Stamenkovic, B. Fowler, B. S. Mun, G. Wang, P. N. Ross, C. A. Lucas, N. M. Markovic, Science 2007, 315, 493.
[4] I. Robinson, R. Harder, Nat.
Mater. 2009, 8, 291.
[5] J. Carnis, A. R. Kshirsagar, L. Wu, M. Dupraz, S. Labat, M. Texier, L. Favre, L. Gao, F. E. Oropeza, N. Gazit, E. Almog, A. Campos, J.-S. Micha, E. J. M. Hensen, S. J. Leake, T. U. Schülli, E. Rabkin, O. Thomas, R. Poloni, J. P. Hofmann, M.-I. Richard, Nat.
Commun. 2021, 12, 5385.
Figure 1. Schematic representation of observed strain distribution over a Pt nanoparticle in 0.05 M H2SO4.

Figure 1
Understanding CO2 Electrolysis Reactionmechanisms Via pH and Isotopic Labeling Studies
Authors: Seger Brian , Deng Wanyu , Gong Jinlong 
Published: July 2022

CO2 electrolysis is a highly useful technique allowing us to upconvert society’s major greenhouse gas into a variety of useful chemicals. However, mechanistically the process is still not totally understood both in 2 electron reduction products (e.g. CO) and in >2e- reduced products (e.g. ethanol/ethylene). This work will discuss using pH variations and deuterium to gain further insight into these mechanisms.
One area of debate for 2 electron transfer reduction products such as CO and formate is whether the rate limiting step involves a proton, a water molecule, or is simply due to adsorption of the CO2 onto the surface. This work will show the benefits of using deuterated water to help resolve this mechanism. By focusing on catalysts geared towards 2 electron transfer reactions to either formate or CO, we have a simple system to break down the mechanism into the reaction order in terms of protons and water molecules. Variations in pH from 3-7 allows us to show the influence of protons for CO or formate, with H2 evolution on a given catalysts acting as a benchmark. Using deuterated water allows us to denote the influence of water, again using H2 evolution as a benchmark catalyst. Combining both these influences we can mechanistically break down the reactions to denote the mechanism of the rate limiting step. (Since we have obtained relatively straight Tafel slopes over 3 orders of magnitude in current, this entails mass transfer is not significantly influencing our results.)
From our results we show that Au and Ag produce a self-consistent mechanism for CO2 to CO reduction, whereas Sn and In produce a self-consistent mechanism for formate evolution. Pd is unique in that it has the ability to solvate hydrogen and deuterium, thus the combined pH variations and deuterium demonstrates how this effect influences our mechanistic understanding.
For greater than 2 electron transfer processes (using Cu) two of the major issues are determining the rate limiting step and the branching point between ethanol and ethylene. We will show how variations in pH and using deuterated water can give insight into both of the aforementioned issues.
Mapping the Double Layer Using Proton-Coupled Electron Transfer at Functionalized Carbon Electrodes
Authors: Owhoso Fiki V , Kwabi David G. 
Published: July 2022

Conductive electrodes functionalized with molecularly well-defined species are emerging as effective active materials for a wide range of applications, from electrocatalytic CO2 and O2 reduction, to high performance lithium-sulfur batteries.1–3 For redox-active species that participate in proton-coupled electron transfer (PCET), the extent of conjugation, applied potential, and distance between the redox center and electrode determine the potential and electric field experienced at the site of electron transfer. This electric field in turn determines the pH-dependent energetics of electron transfer (i.e. Pourbaix behavior) and the rate PCET. We discuss how measurements of PCET to redox-active species functionalized to carbon electrodes can yield insight into the potential and electric field profiles within the electrode-electrolyte double layer. Systematically increasing the distance between the redox-active moiety and the electrode results in the moiety experiencing a progressively weaker electric field, as determined by changes to PCET behavior. Based on these results, we propose strategies to quantify the strength of the electric field as a function of this distance. This work can inform strategies for effective pH modulation at electrified interfaces in ways that can enhance electrocatalytic processes and other applications, such as electrochemical CO2 capture based on pH swing.
References

Ren, G. et al. Porous Core-Shell Fe3C Embedded N-doped Carbon Nanofibers as an Effective Electrocatalysts for Oxygen Reduction Reaction. ACS Applied Materials and Interfaces
8, 4118–4125 (2016).

Zhang, S., Fan, Q., Xia, R. & Meyer, T. J. CO2 Reduction: From Homogeneous to Heterogeneous Electrocatalysis. Accounts of Chemical Research
53, 255–264 (2020).

Zhao, C.-X. et al. Semi-Immobilized Molecular Electrocatalysts for High-Performance Lithium–Sulfur Batteries. Journal of the American Chemical Society
143, 19865–19872 (2021).
Visualizing the 2nd Layer: 4,4´-Bipyridine Adsorption on Sb(111) from EMImBF4
Authors: Ers Heigo , Siinor Liis , Pikma Piret 
Published: July 2022

Room temperature ionic liquids (RTIL) have had a lot of attention in modern chemical research. Due to their high stability under applied electrode potential, the wide electrochemical window and dual usability as a solvent and an electrolyte RTILs have become very attractive in the field of applied electrochemistry and modern energetics [1]. Molecular self-assembly at solid surfaces, resulting in the formation of the nanostructures with well-controlled properties and functionality reveals fascinating perspectives in science and technology at nanoscale [2]. For instance, the smart tailoring of the structural properties of the functionalized electrodes enables SAMs to be used as protective coatings and for the fabrication of organic thin-film transistors and sensors, and as triggers of specific electrochemical processes.
In this study the in situ STM and impedance spectroscopy methods have been applied to study the structure and properties of the electrochemically polished Sb(111) single crystal electrode | EMImBF4, and EMImBF4 + 1% 4,4´-bipyridine, interface.
Using in situ scanning tunnelling microscopy, the adsorption/desorption of 4,4’-bipyridine was demonstrated and a dense underlying structure, formed below a sparse self-assembled monolayer, was visualized. The detection of two separate adsorbed layers indicates that the ordering of organic molecules could extend well beyond the monolayer on the electrode’s surface. These insights are of fundamental and practical importance in the development of nanoelectronics.
References:
[1] H. Ohno (Ed.), Electrochemical Aspects of Ionic Liquids, John Wiley & Sons, Inc., New Jersey, 2005, p.1.
[2] T. Wandlowski, Phase Transitions in Two-dimensional Adlayers at Electrode Surfaces: Thermodynamics, Kinetics, and Structural Aspects, A.J. Bard, M. Stratmann (Eds.), Encyclopedia of Electrochemistry, Wiley VCH, Weinheim (2002) p. 383-471.
Acknowledgments:
This work was supported by the Estonian Research Council grant PSG249 and by the EU through the European Regional Development Fund under project TK141 (2014-2020.4.01.15-0011). For providing us with the computational resources, we would like to acknowledge the HPC Center of the University of Tartu.
(Digital Presentation) Amperometric Gas Sensor with Porous Electrodes Manufactured Via Laser Ablation
Authors: Struk Daniel , Paik Seung-Joon , Shafer Richard H. , Hesketh Peter J. , Patel Vinay , Peaslee David , Findlay Melvin , Stetter Joseph R. 
Published: July 2022

Hydrogen sulfide, Nitrogen Dioxide, and sulfur dioxide are highly toxic gases with health effects at ppb and ppm levels in air. These compounds occur in industrial operations as well as in environmental atmospheric polluted air. Traditionally, microfabricated electrochemical gas sensors use photolithography processes for patterning of the electrodes and defining the electrode geometry for high surface area to increase the sensor gas sensitivity. We present herein a series of gas sensor designs fabricated via laser ablation of sputtered Au films. For these sensors, the laser ablation step itself takes less than two hours to pattern up to 60 sensors.
The sensors are fabricated on a porous hydrophobic substrate made of layers of a Teflon woven mesh, and the 400 nm gold film was sputtered onto a 100 nm tungsten adhesion layer. A total of 60 sensors was patterned in a 6 by 10 grid per substrate with each sensor having a footprint of 15 mm x 15 mm. An image of some of the sensors and their corresponding designs are illustrated in figure 1.
Laser ablation was performed by an Optec WS-Flex USP femtosecond 1030 nm laser. The pulse frequency was set to 400 kHz and both the speed and jump speed were set to 200 mm/s. The laser power is nominally 4 W and the power percentage setting was determined for each substrate by patterning a test array onto the substrate in increments of 2%. From this test array, the lowest power that completely ablated the gold could be determined and that was used for the remaining sensor ablation. Images of the etched surface area shown in the figure 1. Surface analysis with EDS using SEM microscope indicated the composition of the layers and effective removal of the gold from the Teflon sheet without damage to the Teflon porosity in the woven mesh, figure 2.
The sensor electrodes were assembled by lamination between several plastic layers and then an electrolyte was added. The assembled sensors were diced from the assembled 10x6 sensor wafer and individual sensors were connected to a potentiostat and tested via exposure to the various pollutant gases. The current response of these amperometric sensors was measured and found to be linear with respect to concentration in the low ppm range. This work illustrates an alternative to photolithography for the preparation of thin film gas porous electrodes for use in amperometric gas sensors.

Figure 1
Flexible Nonenzymatic Electrochemical Sensor for the Analysis of Urea in Artificial Sweat
Authors: Yoon Jaesik , Sim Myeongseok , Lee Doohee , Cha Yoolim , Wu Guodong , Kim Wonhyeong , Oh Tae-Sik , Yoon Young Soo , Kim Dong-Joo 
Published: July 2022

Recently, wearable and flexible electrochemical sensors have attracted tremendous attention due to health monitoring and diagnostics for humans [1]. Such wearable devices will be able to provide low-cost, easy-to-use, and mass production for in-situ detection or point-of-care applications. Urea is an essential biomarker for the diagnosis of healthy kidneys because urea, a protein metabolite, is formed by the function of kidneys and is excreted into the urine. An abnormal concentration of urea can indicate potential kidney dysfunction. Although most urea sensors are based on the enzyme, the electrochemical sensors to use the nonenzymatic urea oxidation can provide higher stability, biocompatibility, and nontoxicity if nonenzymatic urea sensors address the hurdles such as high conductivity, a narrow range of urea reactions, and limited catalytic activities [2-4]. In addition, a sweat-based urea sensor may show good anti-interference performances for urea detection as the urea concentration in the sweat is 3.6 times higher than that of serum [5].
Herein, we report a sensitive and selective nonenzymatic urea sensor [6]. Flexible and wearable platforms were fabricated using electrospinning polystyrene (PS) containing carbon nanotube as a conductive component. For nonenzymatic catalysts, Ni-Cu alloys were co-sputtered on the PS substrate and transformed to a Ni-Cu oxyhydroxide form by cyclic voltammetry treatment. Such an electrode structure with porous PS is believed to provide sufficient active sites, easy access to reactants, and adequate water wettability for effective charge transfer. The fabricated sensor presented an excellent linear response of 2.00-30.00 mM with a high sensitivity of 10.72 μAmM–1 cm–2 and 4.67 μM LoD for urea detection in neutral pH solution and artificial sweat. The dynamic bending test via 200 times and up to 150° angle bending showed excellent mechanical tolerance where bending deformation of the sensor platform does not affect electrochemical performance.
References

Bariya, Mallika, et al. “Wearable sweat sensors.” Nature Electronics 1, 160-171 (2018).

Debata, Suryakanti, et al. "Design of CdV2O4-V6O13 micro flowers for non-enzymatic electrochemical detection of urea." In AIP Conference Proceedings, vol. 2115, no. 1, p. 030058. AIP Publishing LLC (2019).

Yoon, Jaesik, et al. “Silver-Nanoparticle-Decorated NiOOH Nanorods for Electrocatalytic Urea Sensing.” ACS Applied Nano Materials 3, 7651-7658 (2020).

Yoon, Jaesik, et al. “Ag/ZnO Catalysts with Different ZnO Nanostructures for Non‐enzymatic Detection of Urea.” Electroanalysis 31, 17-21 (2019).

Thudichum, J. L. W. "On the analysis of urea in urine for clinical purposes." British medical journal 1, 38, 788 (1857).

Yoon, Jaesik, et al. “Flexible Electrochemical Sensor Based on NiCu(OOH) for Monitoring Urea in Human Sweat.” Journal of Electrochemical Society 168, 117510 (2021).
(Invited) Rare-Earth-Based Nanoparticles As Multimodal Bioprobes
Authors: Hemmer Eva 
Published: July 2022

The remarkable optomagnetic properties of the rare-earths (RE) make RE-based materials ideal for biomedical applications, including diagnostic (e.g., imaging, nanothermometry) and therapeutic (e.g., drug delivery, photodynamic therapy) approaches. This is due the unique electronic properties of the f-elements allowing for upconversion and near-infrared emission under near-infrared excitation as well as high magnetic moments.
Yet, challenges remain; low emission intensity and efficiency of small nanoparticles (NPs), and reliable, fast synthesis routes. As material chemists, we tackle these challenges with new designs of RE-NPs by chemically controlled synthesis, application-oriented surface chemistry, and understanding of structure-property-relationships. Sodium rare-earth fluorides (NaREF4) are our favorite materials, and we developed a fast and reliable microwave-assisted synthesis approach allowing crystalline phase and size control in the sub 15nm realm. Such control is crucial for the understanding of fundamental structure-property relationships and to optimize their optical and magnetic properties, when aiming for the design of next-generation optical probes or contrast agents for magnetic resonance imaging. For instance, NaGdF4 NPs are gaining interest as alternative MRI contrast agent, while co-doping with RE3+ ions renders them excellent candidates for photoluminescent optical probes. The hexagonal crystalline phase of NaGdF4 is known as the more efficient host material for upconversion emission, yet interestingly, it was found that its cubic counterpart shows superior performance as MRI contrast agent. Having a fast and reliable synthesis route towards NaREF4 NPs on hand, we now explore various nanoparticle architectures and compositions with the goal to optimize their optomagnetic properties, ultimately resulting in the design of biocompatible multimodal bioprobes.
This presentation will shed light on recent results and remaining challenges in the field of RE-based nanostructures with respect to their microwave-assisted synthesis as well as structural and optomagnetic properties, seeking biomedical application, while also touching on hyperspectral imaging as an emerging analytical tool offering spatio-spectral information about RE-based materials.
(Invited) Designed DNA Nano-Switches As Sensitive Electrochemical Biosensors
Authors: Yu Hogan (Hua-Zhong) 
Published: July 2022

Functional nucleic acid receptors (aptamers) have emerged as effective and robust recognition elements for state-of-the-art biosensors. Analytical readouts from aptamer-based biosensors (whether optical, electrochemical, or otherwise) derive primarily from global-scale conformational changes induced in the aptamer domain by analyte binding. Herein, we describe a unique biosensor design principle that represents a distinct alternative to this paradigm; particularly we demonstrate the ready applicability of this design principle in the de novo creation of electrochemical sensors for a clinical analyte of current interest. The function of the class of biosensors we describe, termed “DNA nano-switches”, is designed to depend on the integrity of duplex DNA-mediated charge transfer between an electrode and a redox label.
[1] Thomas, J. M.; Chakraborty, B.; Sen, D.; Yu, H.-Z. J. Am. Chem. Soc.
2012, 134, 13823–13833.
[2] Tang, Y.; Ge, B.; Sen, D.; Yu, H.-Z. Chem. Soc. Rev.
2014, 43, 518–529
[3] Ma, F.; Qi, L.; Einarson, O.; Sen, D.; Yu, H.-Z. Anal. Chem.
2019, 91, 8244−8251.

Figure 1
Enzyme-Free Glucose Monitoring Patch
Authors: Yeasmin Sanjida , Wu Bo , Ullah Ahasan , Zhang Xueqiao , Cheng Li-Jing 
Published: July 2022

Monitoring of glucose levels in non-invasive biofluids, such as saliva and sweat, can advance personal health tracking. However, the approach remains challenging due to the low glucose concentration in saliva and sweat, about 100 times lower than in the blood. Commercial glucose sensors rely on glucose oxidase to measure blood glucose levels with enzyme reactions. The enzyme activity varies with pH, oxygen level, and temperature (more than 40ºC). Also, the method often suffers from cross-reactivity with other sugar molecules, such as maltose and xylose [1]. Thus, it is crucial to develop highly sensitive and stable non-enzymatic sensors for detecting glucose in non-invasive biological fluids.
In this work, we present an enzyme-free, reagent-free electrochemical glucose monitoring patch based on a glucose imprinted polymer nanocomposite. The nanocomposite comprises redox-active chitosan-ferrocene (Cs-Fc) wrapped multi-walled carbon nanotubes (MWCNTs). The Cs-Fc is a polymer with covalently secured redox-active ferrocene, effectively preventing the out leakage of redox substances [2]. The incorporation of MWCNTs increases the surface area, conductivity, and electron transfer rate. The glucose imprinted layer was grown on the surface of the nanocomposite by electropolymerization of functional monomers o-phenylenediamine (o-PD) and 3-aminophenylboronic acid (APBA) in the presence of glucose templates. The successful removal of template molecules created glucose speciﬁc recognition sites in the polymer matrices. The sensor directly detected the presence of glucose upon their binding into these cavities. The electrochemical property of the modified sensor was characterized by cyclic voltammetry (CV) in a potential range of 0-0.5 V at a scan rate of 100 mVs-1 in 1x PBS (pH 7.4) solution. For glucose sensing, the sensor was immersed in a sample solution containing different glucose concentrations for 30 min. We have optimized the composition ratio and assay conditions for sensitive glucose detection. Preliminary results indicated a change in redox peak current of ~2.7 times relative to the control upon adding 1 mM glucose, as shown in Figure 1. The proposed glucose patch is label-free, reagentless, cost-effective, easy fabrication, and expected to be utilized for sensitive and selective glucose detection from sweat.
References
[1] Hwang, D.W., Lee, S., Seo, M. and Chung, T.D., 2018. Recent advances in electrochemical non-enzymatic glucose sensors–a review. Analytica chimica acta, 1033, pp.1-34.
[2] Wu, B., Yeasmin, S., Liu, Y., and Cheng, L.J., 2022. Sensitive and selective electrochemical sensor for serotonin detection based on ferrocene-gold nanoparticles decorated multiwall carbon nanotubes. Sensors and Actuators B: Chemical, 354, p.131216.

Figure 1