bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Pd Monolayer Catalyst As Transformative Concept for Electrolytic Hydrogen Isotope Separation
Authors: Shirazi Mehrnaz , Solanki Dhaivat , Ahmadi Kamyar , Bao Jiming , Miljanic Ognjen , Brankovic Stanko
Published: July 2022

The effect of strain in Pd monolayer catalyst is explored for electrolytic hydrogen isotope separation. Positive/negative strain increases/decreases strength of adsorbed hydrogen bond in overpotential region where recombination of hydrogen atoms is the rate determining step in hydrogen evolution reaction. As a result, the increased/decreased hydrogen isotope separation efficiency of Pd monolayers is expected as compared to bulk Pd. The positive/negative strain rises/lowers diffusion barrier for adsorbed hydrogen atoms. This effect favors/retards recombination of isotopes with smaller mass. As the surface is stretched/compressed, the neighboring adsorption sites separate/approach each other which affects heavier hydrogen isotopes more/less and result in their lower/higher probability for recombination. All these fundamental consideration indicate that Pd monolayers with different level of strain should have much different separation factors than corresponding bulk electrodes. To study described effects, Pd monolayers we synthesized electrochemically on Au(111) and Ru(0001) electrodes each yielding qualitatively different strain levels (Au-positive, Ru-negative). The adsorption strength of hydrogen isotopes is studied by infra-red spectroscopy. These results are input in classical models for isotope separation[1] T calculations. The calculated ratio between the rates of hydrogen and deuterium recombination and separation factors for Pd monolayers and corresponding bulk electrodes are compared to experimentally measured ones. The following discussion focuses on understanding and quantification of strain effects on separation efficiency of Pd monolayers.

[1] B. E. Conway, Proceedings of The Royal Society of London, A. Mathematical and Physical Sciences, 247, 400 (1958).
Acid Anion Electrolyte Effects on Platinum for Oxygen and Hydrogen Electrocatalysis
Authors: Zamora Zeledon Jose Andres , Kamat Gaurav Ashish , Gunasooriya G. T. Kasun Kalhara , Dull Samuel , Perryman Joseph T. , Norskov Jens , Stevens Michaela Burke , Jaramillo Thomas F
Published: July 2022

Platinum (Pt) plays a key role as an electrocatalyst in renewable electrochemical energy technologies such as fuel cells and electrolyzers. Better understanding the interfacial phenomena at the Pt-electrolyte interface can help guide microenvironment engineering to tune performance via electrolyte effects. Herein, we investigate the effect of electrolyte, and more specifically anion, identity on the activity of Pt for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and hydrogen oxidation reaction (HOR) at pH 1. In short, while we see the HER/HOR performance is similar across all three electrolytes, ORR activity trends as HClO4 > HNO3 > H2SO4, and OER activity trends as HClO4 > HNO3 ~ H2SO4. Notably, we observe ORR performance in HNO3 can be improved 4-fold compared to in H2SO4. With combined experimental-theoretical methods, namely cyclic voltammetry and density functional theory anion free energy of adsorption calculations, we hypothesize that the role of the ClO4
–, NO3
–, and HSO4
–/SO4
2– anions can vary as a function of applied potential. Moreover, we note that our rather innovative measurements of Pt hydrogen and oxygen electrocatalysis in nitric acid suggest that a nitrate-like microenvironment in Pt membrane electrode assemblies (MEAs) could present opportunities to enhance the catalyst-ionomer-membrane interface in electrochemical devices such as fuel cells and electrolyzers. This works provides guidance for rational design/engineering of electrocatalyst microenvironment and highlights the microenvironment importance in modulating catalytic performance.
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.
Ultrasmall Co9S8 nanocrystals on Carbon Nanoplates for Efficient Bifunctional Oxygen Electrocatalysis
Authors: Gao Xiaolan , Li Ge
Published: July 2022

Electrochemical energy storage and conversion technologies based on electrocatalysis have been attracting more and more attention addressing increasing concerns on fossil fuel crisis and environmental deterioration. Fuel cells, zinc-air batteries, and water electrolyzer are believed to be promising candidates due to the environmental friendliness and high efficiency. These systems are associated with key reactions including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Due to slow kinetics of these reactions, efficient electrocatalysts, e.g., Pt for ORR and RuOx/IrOx for OER, are usually required to overcome the energy barrier in electrochemical reactions to increase the reaction rate. However, the most advanced electrocatalysts are still based on above-mentioned noble metals with high cost and scarcity, which inevitably retards the large-scale commercialization of these noble metal-based energy systems. It is of great significance to replace noble metal catalysts with earth-abundant, cost-effective, and highly efficient catalysts. Here, we reported the controlled synthesis of ultrafine Co9S8 nanocrystals embedded in N, S-codoped multilayer-assembled carbon nanoplates (Co9S8/NSCP) for highly efficient oxygen electrocatalysis. The bifunctional Co9S8/NSCP electrocatalyst displays a high half-wave potential for ORR, and a low overpotential for OER in 0.1M KOH at a current density of 10 mA cm -2, much better than those of single component counterparts (Co9S8 or carbon) and comparable to noble metal catalysts. The high performance of Co9S8/NSCP can be attributed to the rationally designed hierarchical architecture with nanosized Co9S8 nanocrystals, rich N, S-codopants, highly exposed surface area, and protective graphitic layers, providing abundant active sites with full utilization and stable carbon support towards fast catalytic kinetics and durability. This work will promote further research on the development of highly efficient and stable non-noble metal electrocatalysts for ORR and OER.
(Keynote) Deciphering Electrocatalytic Reactions with Theory and Computation: The Case of CO2 Reduction
Authors: Eikerling Michael , Zhu Xinwei
Published: July 2022

The interfacial region between metal surface and aqueous electrolyte is of central importance for electrochemical reactions. The need to understand the properties of this electrochemical double layer (EDL) region drives extensive research.1,2 A foremost goal of research in electrocatalysis is the development of a theoretical-computational framework. The fundamental task for such a framework is to unravel the complex interplay of electronic structure effects of the catalyst material, potential-induced variations of the chemisorption state, local reaction conditions on the electrolyte side, and electrochemical kinetics of reactions of interest. A recently developed theoretical approach revealed the non-monotonic charging behaviour of a Pt electrode3 and it was thereafter used to decipher the oxygen reduction reaction.4 In the present work, we adapt this approach to study how the local reaction environment dictates the mechanism and kinetics of reduction to CO at an Ag electrode. Our hierarchical model accounts for the multistep reaction kinetics of surface reactions, local chemical equilibria (involving CO2, HCO3
-, CO3
2-, OH-, H+), the specific surface charging state at a given electrode potential, solvent polarization and ion density variations, and reactant/product transport. It integrates interface and pore-level models to account for this interplay. The combined approach rationalizes the impact of the considered effects on the kinetics of the reaction, manifested experimentally in changes of the effective Tafel slope as a function of electrode potential. Lateral interactions between chemisorbed species are seen to contribute to the decrease of the CO current density at high electrode potentials, in addition to mass transport effects, surface charging effects and pH increase. We will conclude with a discussion of the parameters that allow tuning the local reaction environment and thus the electrocatalytic activity and selectivity of the electrocatalyst.

1O.M. Magnussen and A. Gross, Toward an Atomic-Scale Understanding of Electrochemical Interface Structure and Dynamics, J. Am. Chem. Soc. 141, 4777–4790 (2019).

2M.J. Eslamibidgoli and M.H. Eikerling, Approaching the Self-consistency Challenge of Electrocatalysis with Theory and Computation, Current Opinion in Electrochemistry 9, 189-197 (2018).

3J. Huang, A. Malek, J. Zhang and M.H. Eikerling, Non-monotonic Surface Charging Behavior of Platinum: A Paradigm Change, J. Phys. Chem. C 120, 13587-13595 (2016).

4J. Huang, J. Zhang and M. Eikerling, Unifying Theoretical Framework for Deciphering the Oxygen Reduction Reaction on Platinum, Phys. Chem. Chem. Phys. 20, 11776-11786 (2018).
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.
Fcc/2H and Fcc/4H Copper Nanosheets for Carbon Dioxide Reduction
Authors: Chen Shutang , Chen Gugang
Published: July 2022

The fcc/hcp (face centered cubic/hexagonal close-packed) noble metal nanomaterials have demonstrated excellent catalytic performance towards hydrogen evolution reaction and CO2 reduction reaction. Among all the monometallic catalysts, copper has drawn great attention because of its unique ability to convert CO2 into hydrocarbon products with an appreciable selectivity. However, the wet-chemistry synthesis of fcc/hcp Cu heterophase nanostructures still remains a great challenge. Herein, we reported a high temperature solution reduction method to synthesize heterophase Cu nanosheets with a thickness of 28 nm and a diameter of 85.6 nm. The heterophase Cu nanosheets exhibited high selectivity towards CO2 reduction reaction and high faradaic efficiency for methane production (60.2%) at -1.25 V vs RHE. Atomic-level structural investigation revealed the existence of side surface fcc/2H and fcc/4H heterophase (face centered cubic; 2H: hexagonal close-packed with stacking sequence of “BC”; 4H: hexagonal close-packed with stacking sequence of “ACB”). First-principles calculations suggest that the existence of fcc/2H and fcc/4H heterophase interface possess lower ΔG*CHO compared to a fcc Cu surface, indicating a lower kinetic barrier for CO2 reduction reaction.
(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).
(Digital Presentation) Electrochemical CO2-to-Formate Conversion on Metastable Tin Oxide Catalyst in a Catholyte-Free Electrolyzer
Authors: Kim Taewoo , Devalla Vivek S , Dorr Sara , Fenning David P
Published: July 2022

Designing an efficient electrocatalysis system for CO2 conversion to desired value-added products with high selectivity and activity holds promise to enable carbon neutrality and industrial application. Herein, we construct and test two hypotheses: (1) metastable tin oxides play a critical role in enhancing CO2-to-formate conversion rather than metallic tin, and (2) a catholyte-free electrolyzer, where no electrolyte is present on the cathode side, enables highly concentrated formate generation. We prepare tin oxide thin films on a gas diffusion layer by thermal evaporation and confirm the co-existence of SnO and SnO2 on the as-prepared tin oxide films. Annealing in air is used to increase the oxidation of tin prior to starting CO2 electrolysis. In subsequent CO2 electrolysis, we demonstrate that the selectivity for formate is substantially enhanced while parasitic hydrogen evolution reaction is suppressed on the annealed tin oxide electrodes as compared to the as-prepared. The increased selectivity for formate would suggest the presence of metastable tin oxide species during electrolysis favors formation of *OCHO, a key intermediate of formate generation, while suppressing *H and *COOH formation. We also achieve a concentration of formate at the end of 3 hrs electrolysis is > 1 mol L-1. We will describe our latest understanding of the change in surface chemistry modulated by post-heat treatment, providing insights into the role of metastable tin oxide on the highly selective CO2-to-formate conversion.
Photoelectrochemical Hydrocarbon Oxidation Augmented By Plasmonic Nanostructures
Authors: Boltersdorf Jonathan , Forcherio Gregory , Leff Asher , Ostovar Behnaz , Cai Yiyu , Link Stephan , Baker David R.
Published: July 2022

Solar energy can be absorbed via surface plasmon resonance (SPR) to promote excitation of energetic, or “hot”, charge carriers that can be locally transferred or thermally dissipated to augment photocatalytic processes. The “hot” carriers can selectively drive energy-intensive photoelectrochemical reactions at low temperatures by activating adsorbed reactants and accelerating surface kinetics. Plasmonically-sensitized nanocatalysts were investigated for their photocatalytic and photoelectrochemical oxidation of ethanol, with an emphasis on carbon-carbon bond cleavage, under solar simulated-light irradiation. Material approaches included the (i) SPR-functionalization of a traditional metal oxide semiconductor (TiO2) and (ii) bimetallic nanocatalysts composed of epitaxially photodeposited catalytic Pd at targeted locations on plasmonic Au nanorods. Results are correlated with nanocatalyst morphology, composition, and homogeneity to maintain SPR-induced charge separation and mitigate carbon monoxide poisoning. Ensemble photoelectrochemical measurements were complimented with single-particle dark-field scattering and photoluminescence spectroscopies to understand the extraction and utilization of SPR-excited “hot” carriers. Ethanol oxidation was achieved, yielding a solar-driven method for low temperature, complete photo-oxidation of complex hydrocarbons via plasmonic photocatalysis.
Bioinspired Nanomaterial Synthesis and Applications in Catalysis
Authors: Mauzeroll Janine
Published: July 2022

We will discuss the use of a tobacco mosaic virus coat protein (TMVCP) as a versatile platform to synthesize a series of metallic nanomaterials and their applications in energy related electrocatalytic reactions. Taking advantage of the self-assembly properties of TMVCP under different solution conditions, nanoparticles can be embedded onto the disk protein surface or capped by protein subunits. We show that in addition to the eco-friendly synthesis merit, the as prepared materials are superior catalysts in electrocatalytic reactions. While the nanosized silver rings exhibit significant enhancement towards catalysing electrochemical carbon dioxide reduction reaction, the TMVCP-templated two platinum catalyst are promising candidates for methanol oxidation reaction. Besides electrocatalysis, potential applications of protein-metal hybrid systems in heterogeneous organic synthesis are also described. Gold and palladium nanoparticles capped by the bulky protein subunits are employed for two organic reactions and also showed remarkable kinetics.
Trace Analysis of Lead in Michigan Lake Water Using Differential Pulse Stripping Voltammetry: A Comparative Study on the Usage of Controlled Growth Mercury Electrodes Vs Solid State Gold Electrodes
Authors: Vyas Ritesh Navneetrai , Brankle Dane , Howell Jon
Published: July 2022

The concentration of lead in fresh-water samples from the southern shoreline of Lake Michigan was analyzed and compared using two different cell-stands: Controlled Growth Mercury Electrode (CGME) and voltammetry cell stand with disk type gold electrode. Clearly visible Lead (II) peaks at -395 mV and 130 mV were obtained with CGME and Au electrodes respectively using anodic stripping voltammetry (ASV) technique [1-4]. Sensitivity, reproducibility, and ease of usage are compared and reported for each method. While the measured lead concentration was 2.4 ppb using CGME set-up a closely similar concentration of 2.7 ppb was obtained with the gold disk electrode set-up. The sensitivity obtained from the standard addition curve using the gold electrode was over twice that of the CGME. The difference in background currents was attributed to the different electrode materials, bulk diffusion in electrolyte of lead ions, electrode-electrolyte interface and the relative surface areas of the electrode surface. The main convenience associated with the CGME was the fresh electrode surface provided by each new drop, so no further electrochemical cleaning was needed. However, even after repeated polishing of gold electrodes in each run, its inherent sensitivity makes it an ideal candidate for lead determinations with no further requirement of handling the hazardous mercury wastes.

Figure 1
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.
Simple Method to Analyze Degradation of Nonaqueos Polymers
Authors: Kim Jee Woo , Lee Jinhee , Kim Byung-Kwon
Published: July 2022

Polymers are one of the most important materials used in our daily life. Polymers are mainly synthesized from monomers through a process called polymerization, and most synthesized polymers change their state over time. For example, some polymers are continuously decomposed after the polymerization is finished. Gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), and viscometry are commonly used for analyzing the polymers. Each of these methods has their own advantages and disadvantages. However, in common, these methods have disadvantages in that analysis takes a long time and requires a large number of samples. In this study, we have developed an electrochemical method based on cyclic voltammetry to measure the degradation of polymers. To validate our work, we measured the CV under the conditions of polymers degradation. As a result, it was possible to measure different current values in samples in which large amounts of polymers was decomposed. We believe that the method presented here is a sensitively measure the degree of decomposition of polymers, and this method will be of great help in analyzing and maintaining the properties of polymers.
(Digital Presentation) Flexible Electrochemically Reduced Graphene Oxide Sensors for Lead and Cadmium Detection
Authors: De Penning Rebekah , Padalkar Sonal
Published: July 2022

Electrochemically reduced graphene oxide (ERGO) is an excellent sensor material for toxic heavy metal ion detection due to its unique properties. The ERGO combines the conductivity of pristine graphene with oxygen-containing defects that provide active binding sites for ions such as Pb2+ and Cd2+. Sensors can be fabricated directly via electrochemical reduction from graphene oxide (GO) solution. This GO solution can be prepared in bulk by the Hummers method. The ERGO layer thickness can easily be controlled by changing the process parameters during the electrochemical deposition cycle. It can be easily deposited on substrates with varying degree of conductivity including glassy carbon, indium tin oxide on glass, carbon paper, carbon cloth etc. The carbon cloth substrate is particularly interesting in that it is flexible, three-dimensional, conductive and inexpensive. The combination of carbon cloth and ERGO form a sensitive and disposable solution to the simultaneous electrochemical detection of Pb2+ and Cd2+. By using differential pulse anodic stripping voltammetry, ERGO on glassy carbon can detect down to 50 nM of Pb2+ and 100 nM of Cd2+, and could resolve simultaneous oxidation peaks for both ion species. Furthermore, the ERGO-carbon cloth sensor shows vastly improved current response compared to the glassy carbon substrate due to the cloth’s 3D nature and high surface area combined with ERGO’s affinity for heavy metal ions. Therefore, electrochemically reduced graphene oxide and carbon cloth form a promising material combination for heavy metal sensing in water and food products.
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.
(Invited) Enhancing Fluorescence Biosensing By Near-Infrared Emission with Nanomaterials
Authors: Wu Nianqiang
Published: July 2022

This talk has showed the advantages of nanomaterials such as graphene oxide nanosheets and inorganic quantum dots as fluorophores in biosensing. It has also studied the behaviors of visible-light and near-infrared fluorescence emission in blood sample matrix. And plasmonic nanostructures have been designed to enhance near-infrared fluorescence in blood.
(Invited, Digital Presentation) A Breath Tester for COVID-19
Authors: Gouma Perena
Published: July 2022

COVID-19 disease is a pandemic currently, according to the World Health Organization (WHO) caused by the SARS-CoV-2 virus. Without innate immunity to the novel virus and with the lack of therapeutic means to treat it, the only way to contain the spread of this disease further is through early diagnosis. However, for many infected individuals the disease remains asymptomatic, yet they can potentially transmit COVID-19 and unknowingly infect more of the population. The early stages of infection cannot be detected for the most part by the molecular tests used currently for screening individuals for this disease. This work features a new and revolutionary approach to diagnose COVID-19 infection from sampling a single human (breath) exhale. This disruptive approach to infectious disease diagnosis and to the detection of COVID-19 specifically involves sampling the breath of human subjects for gaseous signaling metabolites that signal the disease, that is COVID-19 biomarkers. The relative change in the concentration of these biomarkers upon the subject’s infection with the SARS-CoV-2 virus provides an early and distinct signal of this infection. The COVID-19 breath test utilizes selective resistive gas sensors based on binary nanostructured metal oxides, and by testing the breath of humans infected by COVID-19 and comparing it to the breath signal pattern from controls, a distinct signature of acute COVID-19 disease has been identified. This signal pattern has the shape of the small Greek letter omega (w) and the mechanism behind its formation will be discussed in this talk. Measurements were made repeatedly on infected subjects to map the severity of the disease and to identify when the subject had recovered. Thus, a novel screening/diagnostic tool for the pandemic infection has been developed. The diagnostic device prototype that was developed and used for the clinical testing allowed for the detection of the disease within 15 seconds. This breath test is a rapid, point-of-care, detection tool. In summary, we have established the pathway for the effective diagnosis of the novel coronavirus disease through biomarker monitoring and establishing the specifications required for the early detection of COVID-19. Promoting breath analysis as a first response, on-site, point-of-care, personalized diagnostics method is envisioned. Fast and ubiquitous deployment of the device upon being granted an EUA (our application is still pending at FDA) is anticipated. This is an interdisciplinary project also involving clinicians and infectious disease experts from the Colleges of Medicine and Veterinary Medicine. Support has been provided by the National Science Foundation, the Orton Chair funds and CCTS.
(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.

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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.

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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) Nanomaterials-Based Electrochemical Enzyme Biosensors for Real Time Monitoring of Neurotransmitters
Authors: Andreescu Emanuela Silvana
Published: July 2022

Measurements of neurotransmitter levels are of great physiological and pathological importance and help understanding the state and progression of a variety of neurological diseases. Such studies require the availability of effective methods to probe biochemical processes in real time and allow accurate detection and quantification in vivo. These studies are also important to develop therapies and assess pharmacological effects. However, the presence of neurotransmitters at very low concentrations and variable levels and the complexity of the biological environment pose a great challenge for detection. Electrochemical methods provide real-time measurements in vitro and in vivo. In this presentation, we will discuss design and development of nanomaterials based microbiosensing platforms for the detection of neurotransmitters in vivo, with focus on the monitoring of dopamine, lactate and glutamate. The influence of the electrode design parameters including surface coatings and electrode configurations, and the ability to obtain quantitative spatial and temporal analytical data of the release and distribution of neurotransmitters will be provided with examples of applications. Advantages and limitations of these systems for measurements in real biological environments and the use of oxygen-releasing nanomaterials to address issues related to oxygen limitations and increase sensitivity of measurements in biological environments will be discussed. Our results demonstrate the potential of electrochemical techniques to measure neurotransmitters release in real time and obtain fundamental biochemical-relevant information on physiology, metabolism and disease states in living systems.
(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
Fabricating Potentiometric Biosensors Using 3D Printing
Authors: Glasco Dalton Lee , King Melissa , Bell Jeffrey Gordon
Published: July 2022

Potentiometry, the use of ion-selective electrodes (ISEs), has been incorporated in many point-of-care (POC) applications due to its selectivity and sensitivity. Importantly, ISEs can be translated to low-cost POC devices (e.g., paper-based, thread-based, etc.), making them ideal candidates for commercial applications as they cover many of the guidelines established by the World Health Organization for successful diagnostics in low to middle income countries. Biosensors are an important class of diagnostic tools used to increase specificity and sensitivity for a particular analyte through the incorporation of molecular recognition elements, aptamers, enzymes, etc. Potentiometric enzymatic biosensors have previously been fabricated where an enzyme is immobilized into an ion-selective membrane (ISM) and used to convert important biomarkers into detectable ions for potentiometric sensing. Although this approach has been previously demonstrated using conventional PVC-based ISMs, the lack of mass production capabilities and the routinely high cost of individual membranes has hindered the advancement of deliverable POC devices for potentiometric biosensing. We recently reported a 3D printing protocol for the fabrication of ISMs, which was shown to reduce both the cost associated with sensor fabrication as well as the time. Herein we report on the advancement of 3D printing techniques to fabricate biosensing membranes for their use in POC applications.
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