bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Characterisation of the Oxygen Reduction Reaction in Realistic Catalyst Layers with a Gas Diffusion Electrode (GDE)
Authors: Kaiser Pascal , Lloret Segura Vicent , Ehelebe Konrad , Cherevko Serhiy 
Published: July 2022

The extremely promising activities of advanced fuel cell catalyst materials achieved in an ideal rotating disk electrode (RDE) environment can frequently not be transferred to technologically relevant membrane electrode assemblies (MEAs). This can mainly be ascribed to a non-optimal catalyst layer composition, which significantly affects the management of educts and products on the catalyst layer surface for the oxygen reduction reaction (ORR). Therefore, the composition of the catalyst layer has enormous potential to significantly improve the performance of these systems in MEA. However, it has to be optimized for each individual catalyst system. Currently, MEA experiments have to be employed for catalyst layer optimization.[1] However, such investigations are time consuming, expensive (large quantities of catalyst and extended test equipment needed) and do not allow independent investigation of either cathode or anode catalyst layer. In order to accelerate catalyst layer optimization screening, the gas diffusion electrode (GDE) half-cell setup for investigating realistic catalyst layers was recently proposed.[2]

In a Pt loading study, it was previously shown that similar performance trends compared to MEA experiments can be achieved.[2] In the present work, we introduce advanced electrochemical characterization methods, such as Oxygen Transport Resistance

[3, 4]
and CO-Displacement

[5]
, which have been developed for MEA technique, to the GDE method. By using a commercial Pt on Vulcan catalyst system, we investigate the impact of Nafion loading on the electrochemical performance. The results show, that high ionomer loadings lead to severe O2 mass transport limitations, whereas for small loadings, lower ionomer coverage are measured. Both result in a significant performance loss at high current densities. Therefore, an intermediate ionomer loading which forms a thin layer of ionomer leads to an optimal performance for the Vulcan carbon support.
This work demonstrates that advanced electrochemical methods can also be applied to GDE setups to shed light on the optimal composition of the triple phase interface of catalyst layers. This is an innovative step for the future to efficiently optimise catalyst systems and to gain fundamental insight into the understanding of catalyst layers.
Literature
[1] K. Ehelebe, D. Escalera-López, S. Cherevko, Current Opinion in Electrochemistry
2021, 29, 100832.
[2] K. Ehelebe, D. Seeberger, M. T. Y. Paul, S. Thiele, K. J. J. Mayrhofer, S. Cherevko, Journal of The Electrochemical Society
2019, 166, F1259-F1268.
[3] D. R. Baker, C. Wieser, K. C. Neyerlin, M. W. Murphy, ECS Transactions
2006, 3, 989-999.
[4] D. R. Baker, D. A. Caulk, K. C. Neyerlin, M. W. Murphy, Journal of The Electrochemical Society
2009, 156, B991.
[5] T. R. Garrick, T. E. Moylan, V. Yarlagadda, A. Kongkanand, Journal of The Electrochemical Society
2016, 164, F60-F64.
Application of Mixed-Metal-Oxides As Active Supports for Dispersed Metal Centers: Enhancement of Electrocatalytic Reduction of Carbon Dioxide
Authors: Chmielnicka Anna , Rutkowska Iwona A. , Kulesza Pawel J. 
Published: July 2022

Application of metal oxides as active matrices in electrocatalysis is particular importance. The hydrous behavior, which favors proton mobility and affects overall reactivity, reflects not only the oxide’s chemical properties but its texture and morphology as well. What is of importance to electrochemical science and technology, certain nonstoichiometric mixed-valence oxides could exhibit pseudo-metallic conductivity and possess appreciable catalytic activity.
For example, mixed oxide systems stabilized through Zr-O-W bonds have been demonstrated to be very attractive acid catalysts exhibiting high catalytic activities and good stabilities in many demanding industrial reactions. For electrocatalytic applications, mixed-valent tungsten(VI,V) oxide and zirconium(IV) oxide have been sequentially deposited and integrated through voltammetric potential cycling to form sub-microstructured films on glassy carbon electrode. The mixed WO3/ZrO2 systems are characterized by fast charge (electron, proton) propagation during the system’s redox transitions. By dispersing metallic copper electrocatalytic nanoparticles (generated from Cu2O) over such active WO3/ZrO2 supports, the electrocatalytic activities of the respective systems toward the reduction of oxygen or carbon dioxide have been enhanced even at decreased loadings in acid media. The enhancement effects should be attributed to features of the mixed metal oxide support such as porosity and high population of hydroxyl groups (due to presence of ZrO2), high Broensted acidity of sites formed on mixed WO3/ZrO2, fast electron transfers coupled to unimpeded proton displacements (e.g. in HxWO3), as well as strong metal-support interactions between nanosized metals (Pt or Cu) and the metal (W, Zr) oxo species. The fact that WO3/ZrO2 nanostructures are in immediate contact with the metallic catalytic sites leads to the specific interactions (via the surface hydroxyl groups) with the reaction intermediates (e.g. CO adsorbates). Mechanistic studies involving chronoamperometric, voltammetric and gas-diffusion electrode measurements are pursued, in addition to spectroscopic and XPS measurements. Results of comparative measurements, involving single components only, will be provided as well.

Acknowledgements: This work was supported by the National Science Center (Poland) under Opus Project (2018/29/B/ST5/02627.
(Invited) N-Doped Carbon Catalysts in Carbon-Dioxide Electroreduction: Effect of the Chemical Composition and Morphology
Authors: Hursan Dorottya , Janaky Csaba 
Published: July 2022

N-doped carbon (N-C) materials are increasingly popular in different electrochemical and catalytic applications. Due to the structural and stoichiometric diversity of these materials, the role of different functional moieties is still controversial. We have synthesized a set of N-C catalysts, with identical morphology (~27 nm pore size). By systematically changing the precursors, we have varied the amount and chemical nature of N-functions on the catalyst surface. The CO2 reduction (CO2R) properties of these catalysts were tested in electrochemical experiments, where CO was the major product in all cases, while CH4 appeared as minor product. Importantly, the CO2R activity changed with the chemical composition. The activity was correlated with the amount of different N-functions, and correlation was found only for the -NOx species. Interestingly, the amount of this species decreased radically during CO2R, which was coupled with the performance decrease. The observations were rationalized by the adsorption/desorption properties of the samples.
In the second part of my presentation I will shed light on the importance of catalyst morphology, using N–C catalysts as a model system. We found that CO2R activity, selectivity, and stability of N–C electrodes are highly dependent on their porosity. The presence of mesopores was demonstrated to be beneficial in achieving high CO selectivity and current density, with an optimal pore size around 27 nm. Even after convoluting factors other than morphology (e.g., surface chemistry, level of graphitization, surface area), the reasons behind the observed trends are complex. CO2 adsorption properties, wetting characteristics, and geometric effects are jointly responsible for the massive difference in the CO2R performance. All these properties must be taken into consideration when we aim to understand the reduction mechanism on different catalysts and while improving the performance further to a technologically relevant level (as alternatives to precious metal catalysts).
Impedance Characterization of OECT Behavior in Enzyme-Embedded Conductive Polymer Matrix
Authors: Sepunaru Lior , Davis Connor 
Published: July 2022

Latest generation glucose sensors use small-form wearables which provide continuous data. These
devices represent the commercial forefront aiming towards personalized and real-time point-of-care
biomedical applications. Currently, device lifetimes are limited due to unknown failure mechanisms and
ex-situ calibration strategies. Creating a method for in-situ sensor diagnostics will allow a bottom-up
approach for designing enzyme-supporting matrixes and calibration strategies inherent to biosensors. To
this end, this work seeks to enhance the understanding of performance, stability, and failure mechanisms
of biologically based electrochemical transistors using impedimetric measurements.
Here, we reveal the fundamental interplay between glucose oxidase loading and the electronic properties
of a commonly used PEDOT:PSS matrix as an encapsulating medium. Fundamental to these studies was
the discovery of conductivity enhancing strategies compatible with preserving enzyme activity. The
enzyme-embedded conductive polymer matrix was used in an organic electrochemical transistor probed
via electrochemical impedance (EI) to determine the causes of performance loss over sensor lifetimes.
Supporting spectroscopies aided in detailing film morphology and electrical property changes associated
with sensor behavior.
A Low-Cost Cellulose-Based POC Device for Detection of COVID-19
Authors: Walia Sunil , Asthana Amit , Liu Juewen , Mitra Sushanta 
Published: July 2022

Point-of-care diagnostic (POC) is of utmost importance for the fight against pandemics which provides easy, instant results right at your place. POC can transform healthcare management and create superior infrastructure. In POC, employing lateral flow assays (LFAs) can accelerate the assessment and shorten the treatment time. LFA is a small handheld device made from paper that controllably delivers the analyte without the need of an active pump to the detection area to produce the signal, generally coloured nanoparticles (Au, carbon).
Conventional LFA device is made of four components, sample pad, conjugate pad, nitrocellulose membrane and absorbent pad arranged sequentially. At the sample pad, the analyte is dispensed. From here, the analyte moves to the conjugate pad and hybridizes with recognition antibodies (placed onto nanoparticles) to form analyte-antibody-gold nanoparticles conjugate. Further movement takes this to the nitrocellulose membrane. Here, other recognizant antibodies are placed at the test and control line to immobilize by forming the sandwich assay with the analyte-antibody-gold nanoparticles. The excess liquid is absorbed in the absorbent pad. From these components of the LFA device, nitrocellulose membrane and antibodies need replacements as they increase the device's overall cost. Cellulose paper holds promise to counter nitrocellulose membrane; however, the development of fabrication methods for cellulose paper-based LFA devices is needed. In comparison to antibodies, aptamers improve batch-to-batch variability, ruggedness, and longevity of LFA devices.
This work describes the fabrication of half-strip cellulose paper (Whatman® Grade 4 filter paper) based LFA device exploiting aptamers as the recognition element for antigen detection. The covalent bonding of aptamers was achieved by NanoCheck-ATH® (NC) and p-phenylene disothiocyanate (PDITC). NC provides plentiful amine functional groups and constricts the test line width by covalently bonding aptamer to the NC region only. The chitosan-based NanoCheck on paper assists in realizing sharp test and control lines by providing the controlled surface for PDITC reaction through amine groups. PDITC functions as a linker between NC and aptamers. Finally, a proof-of-concept nucleocapsid protein of SARS-CoV-2 as an antigen detection was shown with the minimal detectable concentration down to ~20 ng/mL with excellent selectivity towards casein, BSA, and albumin. We envisage that using facile modification chemistry of NC, PDITC, and aptamers for antigen detection will allow the fabrication of paper-based LFA devices in a roll-to-roll setting and, thus, decrease the overall cost. The developed method is generic and can be adapted to detect other antigens to fight future pandemics.
(Keynote, Digital Presentation) A Study of Nanozyme-Based Biosensor
Authors: WANG Erkang 
Published: July 2022

Nanozymes have attracted significant research interest over the world due to their simple preparation, storage, as well as the low-cost compared with natural enzymes. We started to study nanozymes over 10 years ago [1-8]. A few examples of novel nanozymes from our laboratory are shown: 1, NiPd hNPs exhibited triple-enzyme mimetic activities (oxidase-like, peroxidase-like and catalase-like activities). 2, Fe3O4 NPs on 3D porous graphene exhibited enhanced nanozyme activity and used for glucose determination. 3, GOx@ZIF-8(NiPd) nanoflower exhibiting tandem catalysis has been firstly proposed.
Recently, a new nanozyme based on a bionic zeolitic imidazolate framework-8 (ZIF-8) has the active center similar to hCAII, showing hCA as well as esterase and acetylcholinesterase-like activities. A new class of single-atom nanozymes, as FeN5 SA/CNF, with atomically dispersed enzyme-like active sites in nanomaterials has been discovered. The defined single-atom nanozymes provide a new perspective to the catalytic mechanism and rational design of nanozymes and exhibit great potential to become the next-generation nanozymes.

References

H. Wei, E. K. Wang, Chem. Soc. Rev., 2013, 42, 6060-6093.

H. Wei, E. K. Wang, Anal. Chem., 2008, 80, 2250-2254.

Q. Wang, X. Zhang, L. Huang, Z. Zhang, S. J. Dong, Angew. Chem. Int. Ed., 2017, 56, 16082.

S. L. Rong, Y. C. Huang, J. W. Liu, E. K. Wang, H. Wei, Prog. Biochem. Biophys. 2018, 45, 129-147.

Q. Wang, H. Wei, Z. Zhang, E. K. Wang, S. J. Dong, Trends Anal. Chem., 2018, 105, 218-224.

WW. Wu, L. Huang, EK. Wang, SJ. Dong, Chem. Sci. 2020 11, 9741-9756.

J. X. Chen, L. Huang, Q. Q. Wang, W. W. Wu, H. Zhang, Y. X. Fang, S. J. Dong, Nanoscale, 2019, 11, 5960-5966.

L. Huang, J. X. Chen, L. F. Gan, J. Wang, S. J. Dong , Sci. Adv. 2019, 5, eaav5490.

Acknowledgment

This work was supported by the National Natural Science Foundation of China and The Ministry of Science and Technology of China
All coworkers in this laboratory are appreciated for their effort in this area

Key words

Nanozymes, NiPd NPs, GOx@ZIF-8(NiPd) nanoflower, ZIF-8, acetylcholinesterase-like nanozyme , single-atom nanozyme- FeN5 SA/CNF
(Invited) Exploring in the Near Infrared: From Quantum Dots to Rare-Earth Doped Nanoparticles
Authors: Ma Dongling , Yang Fan , Yang Ruiqi 
Published: July 2022

Bioimaging shows great potential for disease detection due to its high sensitivity at the subcellular level and low cost of related imaging facilities. As compared to most commonly used optical probes that are excited and emit in the visible wavelength range, near-infrared (NIR) excitable and emitting nanomaterials are indeed more promising for bioimaging. It is because at certain NIR wavelengths (known as biological windows) tissues are basically optically transparent and show minimal scattering and absorption, allowing for deep tissue imaging. Meanwhile, tissue autofluorescence can also be avoided. In this talk, I will present our recent work [1-4] on the synthesis of NIR-emitting water soluble, stable core/shell/shell quantum dots (QDs) and rare-earth doped nanoparticles, and their use in biomedicine, including but not limited to bioimaging.

References:

[1] ACS Nano 2019, 13, 408-420;
[2] Adv. Funct. Mater. 2018, 1706235 (Inside Back Cover);
[3] Chem. Mater. 2019, 31, 3201-3210.
[4] Science Advances, 2021, 7;7(15):eabc3012
Analysis of Single Blood Entities Using an Ultramicroelectrode through Single-Entity Electrochemistry
Authors: Lee Jungeun , Hong Seungwoo , Kim Byung-Kwon 
Published: July 2022

The research was conducted with the aim of analyzing individual human blood cells in the presence of redox species based on single-entity electrochemistry. Various blood cells (e.g., red blood cell, white blood cell, and platelets) perform a role directly related to survival, such as oxygen transport, hemostasis, and immune response, as they move through the whole body’s blood vessels. However, with the current lab-on-a-chip typed biosensor technology, the factors that can be measured using a small amount of blood are limited to uric acid, cholesterol, glucose, or hemoglobin in the blood. In clinical laboratories, common methods for measuring individual blood counts are automated hematology analyzers based on the automated Coulter cell counting method or flow cytometry, which produce a huge amount of blood count results, but are limited. For this reason, it is proposed a method for detecting individual blood cells that can be applied to a biosensor simply and quickly.
References

Ran, An. et al. (2021) ‘Emerging point-of-care technologies for anemia detection’, Lab on a Chip, 21(10), pp. 1843-1865.

J-H, Lin. et al. (2020) ‘A Multifunctional Microfluidic Device for Blood Typing and Primary Screening of Blood Diseases’ ACS Sensors, 5(10), pp. 3082-3090.

J, Lee. et al. (2020) ‘Determination of Serotonin Concentration in Single Human Platelets through Single-Entity Electrochemistry’, ACS Sensors, 5(7), pp. 1943-1948.

T.L.T, Ho. et al. (2018) ‘Determining mean corpuscular volume and red blood cell count using electrochemical collision events’, Biosensors and Bioelectronics. 110, pp. 155-159.

A-C, Villani. et al. (2017) ‘Single-cell RNA-seq reveals new types of human blood dendritic cells, monocytes, and progenitors’, Science. 356, No.6335.
Fabrication of MoS2 Biosensor By Chemical Exfoliation
Authors: Rezk Ayman , Nayfeh Laith , Nayfeh Ammar 
Published: July 2022

The marriage between nanotechnology and sports is here [1]. We see it in new materials for tennis racquets, to balls, and to goal line technology to name a few [2]. One area that has amazing potential are wearable biosensors to improve the health and stamina of world class athletes [3]. In soccer (football) for example, some of the best athletes in world run almost 10 km during a match so keeping track of their health is very important. These real time bio signals while playing can help to avoid injuries and help long term longevity. The wearables sensors should stick to the athletes’ body seamlessly and not affect their play or performance. This can be done with new nanomaterials and devices. In this work, we use a 2D material, 1.3 nm thick MoS2 nano-flakes, to fabricate a bio sensor that can detect changes in temperature.
The chemically exfoliated MoS2 nano-flakes are drop casted on a lightly P doped Si substrate. 50 nm thick Au metallization layer is deposited on both the back of the substrate and top of MoS2. Followed by another metallization layer using a shadow mask to pattern the top contacts. Finally, silver paste is applied to the back contact before mounting it on a gold-coated steel disc. The sensor is then placed on a hot plate and connected to a probe station where the steel plate is grounded, while the top contact voltage is swept from -5 to 5 V. The IV characteristics are measured from 30 oC to 120 oC with 5 oC increments.
The collected IV plots from the sensor shows better responsivity and higher current response compared to the control sample with no MoS2. We then tested the current flow as function of temperature to detect changes. This simple design with nanotechnology and 2D materials will be fabricated next on flexible substrates and made into wearable device. This is perfect for world class athletes to detect sudden changes in bio-temp and send real time bio-signals to health care professionals.
Finally, the use of bio sensor for athletes will become mainstream soon, help athletes stay healthy and avoid injuries. The use nanotechnology, and nanomaterials will be the key enabler of this. The results here show that 2D materials, like MoS2 are promising for future low cost wearable biosensors. Bibliography

[1]

M. P. Sadaf Abbasi, S. Nizamuddin and N. M. Mubarak, "Chapter 25 - Functionalized nanomaterials for the aerospace, vehicle, and sports industries," Micro and Nano Technologies, pp. 795-825, 2020.

[2]

L. P. d. Costa, "Chapter 14 - Engineered nanomaterials in the sports industry,," In Micro and Nano Technologies, Handbook of Nanomaterials for Manufacturing Applications,, pp. 309-320,, 2020.

[3]

J. Kim, A. Campbell and B. e. a. de Ávila, "Wearable biosensors for healthcare monitoring," Nat Biotechnol, no. 37, p. 389–406, 2019.

Figure 1
(Invited) Ingenious Nanomaterials for Ultrasensitive ECL
Authors: Valenti Giovanni , Rebeccani Sara , Zanut Alessandra , Marcaccio Massimo , Paolucci Francesco 
Published: July 2022

The impact of nanotechnology and nanosystems on analytical science is hardly overlooked. In the search for ever-increasing sensitivity in biomedical sensors, nanoparticles have been playing a unique role as, e.g., ultrabright labels in clinical analysis (markers, tumor cells, and pharmaceuticals) and in the detection of pathogenic microorganisms, toxic agents, and pesticides in the environmental field and food products. Coupling such nanosystems with electrochemiluminescence (ECL), which naturally brings improved signal-to-noise ratio compared to photoluminescence, with minimized effects due to light scattering and luminescence background, has brought about new systems and strategies for analytes determination, even in very complex matrices, such as urine, blood or lysate.
Among the several nanosystems, dye-doped silica nanoparticles (DDSNs) have proved as very promising and versatile nanomaterials in ECL-based bioanalytical platforms. The increase of the number of complexes active in the generation of the ECL signals together with an even larger increase in the signal stability, represents in fact a promising strategy towards ultrasensitive ECL.
Approaches based on ECL generation on the nanoscale using luminophore-reporter-modified DNA-based nanoswitches (i.e., molecular beacon) has been additionally investigated and, in this context, the development of innovative amplification-free detection methods represents a significant breakthrough compared to existing PCR-based methodologies, allowing the integration of nucleic acid detection on portable and low-cost sensor devices, and enabling the massive diagnostic screening.