Physical Chemistry Commons^™

A Promising Modification Of Pt Surfaces With Cnts For Decreasing Poisoning Impact In Direct Methanol Fuel Cells, Yaser M. Asal Mr., Islam M. Al-Akraa Dr, Aya A. Khalifa Ms.

Chemical Engineering

Direct methanol fuel cells (DMFCs) are clean energy sources that have many applications due to the high energy density of methanol as a fuel. However, this type of fuel cells (FCs) has limitations that are preventing it from being commercialized. One such limitation is the adsorption of intermediates such as CO into the surface of the Platinum (Pt) catalyst during methanol oxidation (MO) which deactivates its active sites, where the reaction is taking place, and leads to poisoning of the electrode over the long term. In this study, multi-walled carbon nanotubes (MWCNTs) have been introduced to the Pt-modified glassy carbon …

Recent Advances In Nanofluidic Electrochemistry For Biochemical Analysis, Zhong-Qiu Li, Zeng-Qiang Wu, Xing-Hua Xia

Journal of Electrochemistry

Nanofluidics, as a young research field, has been receiving more and more attentions. It has been successfully applied in various fields including nanoscale separation, biochemical sensing and energy conversion. The development of nanofluidics is closely related to electrochemistry that can provide a driving force for the study of the material transport characteristics in nanopores/nanochannels. On the other hand, nanopores/nanochannels can creat a microenvironment for study of spatially nanoconfined electrochemistry. The combination of nanofluidics and electrochemistry has given rise to many new theories and technologies for single molecule/particle analysis and nanofluid manipulation. Herein, we provide a review of the recent progresses …

Electrocatalytic Nanomaterials For Reduction Of Hydrogen Peroxide As Potential Radioprotectors, Rui-Hong Jia, Jin-Xuan Zhang, Xiao-Dong Zhang, Mei-Xian Li

Journal of Electrochemistry

Nanomaterials have shown many potential application prospects in the biomedical field, such as medical imaging, drug delivery and biosensing due to their unique physical and chemical properties. In this review we focus on nanomaterials that have shown not only abilities of radiation protection, but also good electrocatalytic activities toward reduction reactions of hydrogen peroxide and oxygen. We discuss the abilities of radiation protection of these nanomaterials that are ascribed to their enzyme-like activities because their catalytic properties provide an effective pathway for scavenging free radicals in vivo via rapid reactions with reactive oxygen species. We also provide insights into electrocatalytic …

Electrochemical Biosensors For Wastewater-Based Epidemiology, Yu-Wei Pan, Kang Mao, Franziska Tuerk, Zhu-Gen Yang

Journal of Electrochemistry

Wastewater-based epidemiology (WBE) has been shown to be an innovative approach for evaluation of drug use trends and public health assessment by quantifying drug residues and/or metabolites (so-called biomarkers) in wastewater collected in a local treatment plant. Community sewage sensors have been proposed and demonstrated to be powerful tools for the analysis of sewage biomarkers. In particular, electrochemical biosensors have emerged as a rapid method for the analysis of biomarkers and pathogens in wastewater due to low cost, minimal sample processing and the ability to test in the field. It has been widely used for biomedical diagnosis, environmental monitoring and …

Research Progresses In Structural Modulation And Electrochemiluminescence Of Supertetrahedral Chalcogenide Clusters, Gang Lei, Yang Liu

Journal of Electrochemistry

Electrochemiluminescence (ECL) exhibits a broad application prospect in the field of biological analysis due to its unique performance features, and the exploitation of high efficient ECL reagents offers an important tool for the development of sensors with excellent performance and practical clinical applications. Open-framework supertetrahedral chalcogenide clusters both possess the porous structure of molecular sieve and the excellent optical properties of the semiconductor, so it has attracted more and more attention in ECL analysis. Different from the traditional semiconductor quantum dots, the structure and composition of supertetrahedral chalcogenide clusters can be accurately controlled at the atomic level, and supertetrahedral chalcogenide …

Correlated Optical Imaging And Electrochemical Recording For Studying Single Nanoparticle Collisions, Lin-Lin Sun, Wei Wang, Hong-Yuan Chen

Journal of Electrochemistry

With the development of nano-fabrications in recent years, a novel strategy based on random collisions of single electroactive nanoparticles (NPs) onto an inert ultramicroelectrode (UME) has been emerged in the field of nanoelectrochemistry, and named as single nanoparticles collisions (SNCs). The technique uses a chronoamperometric method to detect transient current generated by random collisions of single NPs onto an UME. By analyzing the current signal, one could study the properties of single NPs. Although this technique can detect electrochemical or electrocatalytic currents of a single NP, the traditional SNCs technology lacks necessary spatial resolution to identify and characterize a specific …

Single Particle Impact Electrochemistry: Analyses Of Nanoparticles And Biomolecules, Jian-Hua Zhang, Yi-Ge Zhou

Journal of Electrochemistry

Single particle impact electrochemistry (SPIEC) has grown rapidly in recent years and shown great promise in the analysis of nanoparticle properties as well as the detection of biomolecules including DNA, RNA, protein, enzyme, bacteria, virus, vesicles and others. This minireview summarizes recent advances in electroanalytical applications of SPIEC according to different analytical methods, i.e., direct electrolysis of nanoparticles or labeled nanoparticles, direct electrolysis of soft particles encapsulated redox molecule, indirect electrochemistry of particles, area and diffusion blocking, and changes in current magnitude and collision frequency.

Cysteine And Cystamine Co-Self-Assembled Monolayers For In Vivo Detection Of Ascorbic Acid, Yue Zhang, Tao-Tao Feng, Wen-Liang Ji, Mei-Ning Zhang

Journal of Electrochemistry

Self-assembled monolayers (SAMs), which form highly ordered monolayers on the electrode surface through the gold-suffer bond, have attracted much attention in recent years. This stable layer not only can regulate the wettable properties of surface, but also can act as a promoter towards redox-active molecules. Here, we developed a simple and effective method to construct cysteine and cystamine co-self-assembled monolayer on gold microelectrode for  in vivo detection of ascorbic acid (AA). The molar ratio at 1:1 of mixed monolayer has been found the optimum to enhance the electron-transfer kinetics of AA oxidation at low potential (ca. 0.10 V), meanwhile, it …

Current Statuses And Challenges Of Wearable, Flexible Electronic Sensors And Energy Storage Devices, Zhong-Qian Song, Fang-Jie Han, Hui-Jun Kong, Jia-Nan Xu, Yu Bao, Dong-Xue Han, Li Niu

Journal of Electrochemistry

With the developments in the internet of things, artificial intelligence and human-computer interaction technology, soft, flexible and wearable electronic devices provide a novel platform for monitoring of the human vital signs, and recognition of human behaviors to connect human being and machine without consciousness. Recent progresses about wearable and flexible electronics that can provide accurate, non-invasive, long-term and continuous monitoring of human vital sings including pulse, temperature, skin activities, breathing and heart rate are summarized. The working mechanisms, current statuses and challenges in temperature sensor, strain sensor and pressure sensor are discussed. The review concludes with a prospect of current …

A Low Noise Temperature Control System For Nanopore-Based Single Molecule Analysis, Cheng-Yu Yang, Zhen Gu, Zheng-Li Hu, Yi-Lun Ying, Yi-Tao Long

Journal of Electrochemistry

Nanopore employs a single bio-molecule interface, which is a highly sensitive single-molecule detection technology for measuring single biomolecules such as DNA, RNA, protein, and peptide. The interaction between single molecule and nanopore is thermodynamically controlled. Therefore, it is urgent to precisely control the temperature of the nanopore system without introduction of any noise. In this paper, we have developed a low-noise temperature control system for single-molecule detection of nanopores to achieve precise regulation at the ambient temperature during measurements. The system utilizes the thermoelectric effect of the semiconductor refrigerating chip to heat or cool the detection chamber, while adopts electromagnetically …

Study On The Relationship Between Structure Of Supramolecular Ion Material And Performance Of Humidity Sensing, Hui-Min Tang, Hai-Long Yan, Li Zhang, Jun-Jie Fei, Ping Yu, Lan-Qun Mao

Journal of Electrochemistry

Humidity measurement and control is one of the most notable issues in various areas, such as climate, industry,
agriculture, electronics, especially human comfort and health. In our previous study, we have found that a new kind of supramolecular
ionic material (SIM), consisting of an imidazolium-based dication (e.g., 1,10-bis(3-methylimidazolium-1-yl) decane, C₁₀(mim)₂) and
electroactive dianionic (e.g., 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS), shows ultrasensitive and ultrafast
response towards humidity sensing. Herein we prepared six kinds of imidazolium-based dications with different carbon chain
lengths (i.e., C₄, C₆, C₈, C₁₀, C₁₂, C …

Recent Progresses Of Enzymes Assembled In Nanochannels For Catalytic Reaction, Li Shangguan, Xuan Xu, Song-Qin Liu

Journal of Electrochemistry

The research of enzymes assembled and catalytic reaction not only is beneficial to exploit the essences of life’s activities, but also is significant in developing the practical application of enzymes in these areas including industrial production, analysis and detection, treatment of disease, etc. The effective immobilization and ordered assembly of enzymes are important methods for maintaining the catalytic activity, catalytic reaction stability and catalytic process controllability of enzymes. Among them, single or multi-enzymes are immobilized orderly in nanochannels that exhibit unique features and advantages, accordingly, the confinement effect of nanochannels can increase the selectivity and catalytic efficiency of enzymes through …

Using Molecular Dynamics To Study Qs21 Interactions And Penetration Of Lipid-Cholesterol Bilayers, Sarai Guerrero, Mikko Karttunen

Western Research Forum

Saponins have been used as adjuvant agents for decades in vaccines and therapies, but none are as well studied or heavily used as QS-21. This achievement is notwithstanding the fact that QS-21 usage is limited by its stability, toxicity, and scarcity. These shortcomings have only pushed researchers to develop and experiment with artificial recreations of the saponin to harness its unique benefits. A considerable number of research hours have been poured into this topic, but like QS-21 there is a shortcoming here as well. The number of articles that look at QS-21 interactions with the bilayer or the conditions under …

Triplet Population Dynamics And Excited State Relaxation In Chalcogenophene Polymers, Benjamin D. Datko

Chemistry and Chemical Biology ETDs

The conventional understanding of intersystem crossing in multichromophoric conju- gated polymers is usually depicted via a pure electronic model, neglecting contributions of vibrations or conformational order. Obtaining accurate structure-function correlations on spin-conversion processes involving photogenerated singlet excitons to triplet excitons and the excited state dynamics requires sensitivity to the subtle conformational ordering within conjugated polymers. This dissertation seeks to understand the kinetics of multi-exciton singlet-triplet interactions and the excited state relaxation of chalcogen containing (S, Se) conjugated polymers. Utilizing single molecule modulation spectroscopy allows determi- nation of triplet formation of individual conjugated polymer chains and aggregates. This technique resolves triplet-induced …

The Spectroscopic And Computational Exploration Of Sulfur Hydrogen Bonding, Andrew Yoonkeun Lee

Honors Projects

Hydrogen bonds are a subset of non-covalent interactions that occur between X-H — Y, in which X and Y are the very electronegative atoms. In our research, we examine the more unconventional hydrogen bond-like interactions of thiol (SH) containing molecules using vapor-phase infrared (IR) spectroscopy and ab initio computational chemistry. When the SH hydrogen bond donor complexes to a hydrogen bond acceptor, a red shift of the SH stretching mode emerges. An anharmonic oscillator local mode model is applied to the ethanethiol-trimethylamine dimer, and we determine that any IR evidence of dimerization in our experiment is likely obscured by the …

Ab Initio Calculations Of Changes In Sulfur’S Orbital Energies And Sizes With Oxidation State As A Means Of Explaining Hypervalency, Anton V. Taraskin

Honors Projects

The energetics and orbital sizes of sulfur’s valence 3d and fluorine’s valence 2p orbitals were measured using a closed active space self-consistent field calculation to determine the degree of possible bonding available to sulfur’s 3d. It was determined that for orbital energies, the cc-pVXZ and aug sets converged hyperbolically onto a single energy value as X increased and that for both fluorine and sulfur orbital energies scaled down linearly with oxidation state. This resulted in a 0.47 hartree difference between the sulfur 3d and fluorine 2p orbitals at S0.6+ and F-0.1, far exceeding the energy gap between 3p and 2p …

Monolayer Triphosphates Mp3 (M = Sn, Ge) With Excellent Basal Catalytic Activity For Hydrogen Evolution Reaction, Hong-Hui Wu, He Huang, Jie Zhong, Song Yu, Qiaobao Zhang, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

Atomically thin two-dimensional (2D) materials have received intense research interest due to their novel properties and promising applications in nanodevices. By using density functional theory (DFT) calculations, we investigate catalytic activities of several newly predicted two-dimensional (2D) triphosphides GeP₃, SnP₃ and InP₃ monolayers for hydrogen evolution reaction (HER). The calculation results show that GeP₃ and SnP₃ monolayers are active catalysts for HER with suitable free energy of hydrogen adsorption in the basal plane. In particular, the Gibbs free energy of hydrogen adsorption (ΔG_H*) of GeP₃ is 0.024 eV, a value even …

Crystal Structure Of Zymonic Acid And A Redetermination Of Its Precursor, Pyruvic Acid, Dominik Heger, Alexis J. Eugene, Sean R. Parkin, Marcelo I. Guzman

Chemistry Faculty Publications

The structure of zymonic acid (systematic name: 4-hy­droxy-2-methyl-5-oxo-2,5-di­hydro­furan-2-carb­oxy­lic acid), C₆H₆O₅, which had previously eluded crystallographic determination, is presented here for the first time. It forms by intra­molecular condensation of parapyruvic acid, which is the product of aldol condensation of pyruvic acid. A redetermination of the crystal structure of pyruvic acid (systematic name: 2-oxo­propanoic acid), C₃H₄O₃, at low temperature (90 K) and with increased precision, is also presented [for the previous structure, see: Harata et al. (1977). Acta Cryst. B33, 210–212]. In zymonic acid, the hy­droxy­lactone ring …

The Investigation Of Methylidyne Radical (Ch) Reactions With Furan, 2-Methylfuran, And 2,5-Dimethlyfuran And The Photoionization And Photodissociation Of Valeric Acid, Erica Carrasco

Master's Theses

This thesis presents the combustion study of three furanic compounds using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at 298 K. The experiments were performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source of the Lawrence Berkeley National Laboratory. The reactions of the three furanic compounds with methylidyne (CH) radicals were analyzed based on their photoionization spectra and kinetic profiles.

Additionally, the unimolecular dissociation of valeric acid was also studied and presented in this work using the double imaging photoelectron photoion spectrometry (i2PEPICO) coupled with synchrotron radiation from the VUV beamline. The experiments were carried out …

Synchrotron Photoionization Study Of 2,5-Dimethylfuran Oxidation Initiated By O(3p) Atoms, And Computational Studies Of Superalkali Species: Li3f2, Heejune Park

Master's Theses

This thesis presents the experimental study of a 2,5-dimethylfuran oxidation reaction initiated by atomic oxygen (O(³P)) and the theoretical investigation of superalkalis properties. The experiments were performed at the Chemical Dynamics Beamline 9.0.2 of the Advanced Light Source (ALS) located at the Lawrence Berkeley National Laboratory in Berkeley, CA. The first chapter discusses world energy consumption and progress towards new sustainable energy sources, mainly focusing on biofuels, along with a basic description of combustion. A description of the superalkalis and a brief history of synchrotron radiation are also presented in Chapter 1. Chapter 2 describes the components of …