Imperfections that disrupt the sp(2) conjugation of graphene can alter its electrical, chemical, and mechanical properties. Here we report on examination monolayer chemical vapor deposited imperfections using scanning electrochemical microscopy in feedback mode. It was found sites with a large concentration defects are approximately 1 order magnitude more reactive, compared to pristine surfaces, toward reactions. Furthermore, successfully passivated activity by carefully controlling...

We present a catalog of electron transfer mediators for investigating the heterogeneous kinetics large-area, single-layer graphene electrodes. Scanning electrochemical microscopy (SECM) was used to probe apparent standard rate constant in aqueous solutions and acetonitrile dimethylformamide, allowing studies electroactivity at different potentials both nonaqueous media. In solution, iron(III) ethylenediaminetetraacetic acid, hexacyanoruthenate(II), hexacyanoferrate(II),...

A major goal of energy research is to use visible light cleave water directly, without an applied voltage, into hydrogen and oxygen. Although SrTiO3 requires ultraviolet light, after four decades, it still the "gold standard" for photo-catalytic splitting water. It chemically robust can carry out both oxygen evolution reactions bias. While ultrahigh vacuum surface science techniques have provided useful insights, we know relatively little about structure these electrodes in contact with...

The surface diffusion of a cobalt bis-terpyridine, Co(tpy)(2)-containing tripodal compound (1·2PF(6)), designed to noncovalently adsorb graphene through three pyrene moieties, has been studied by scanning electrochemical microscopy (SECM) on single-layer (SLG). An initial boundary approach was in which picoliter droplets (radii ~15-50 μm) the were deposited an SLG electrode, yielding microspots monolayer molecules is initially confined. time evolution activity these spots detected at aqueous...

The interaction between electrodeposition of Ni and electrolyte breakdown, namely the hydrogen evolution reaction (HER) via H3O+ H2O reduction, was investigated under well-defined mass transport conditions using ultramicroelectrodes (UME's) coupled with optical imaging, generation/collection scanning electrochemical microscopy (G/C-SECM), preliminary microscale pH measurements. For 5 mmol/L NiCl2 + 0.1 mol/L NaCl, 3.0, electrolytes, voltammetric current at modest overpotentials, i.e., -0.6 V...

Electrocatalytic reduction of CO2 to CO in aqueous media offers an important path more sustainable carbon utilization. Optimization this process relies on a detailed understanding the dynamics boundary layer chemistry, e.g., pH, adjacent electrode, which is difficult quantify without perturbing system. In work, versatile IrOx pH-sensing thin film fabricated ring rotating disk electrode (RRDE) enable potentiometric pH measurement under well-defined mass flow conditions. An analytical...

Infectious diseases, such as influenza, present a prominent global problem including the constant threat of pandemics that initiate in avian or other species and then pass to humans. We report new sensor can be specifically functionalized detect antibodies associated with wide range infectious diseases multiple species. This biosensor is based on electrochemical detection hydrogen peroxide generated through intrinsic catalytic activity all antibodies: antibody catalyzed water oxidation...

Silicon photoanodes patterned with thin-film Ni catalyst islands exhibited stable sunlight-driven O₂evolution for over 240 h of continuous operation in 1.0 M KOH.

Over the past decade, there has been a great deal of interest in graphene with regards to its electrochemical behavior. Previous studies have focused on understanding fundamental processes such as charge transfer and molecular transport at graphene–electrolyte interface well applications electronic, optical, mechanical systems. We present illustrative examples large area, single layer platforms for optical sensing devices microfluidic Three modified thin polymer films are discussed. explored...

Understanding the role of macroscopic and atomic defects in interfacial electron transfer properties layered transition metal dichalcogenides is important optimizing their performance energy conversion electronic devices. Means determining heterogeneous rate constant, k, have relied on deliberate exposure specific electrode regions or additional surface characterization to correlate proposed active sites voltammetric features. Few studies investigated electrochemical activity features under...

A combined scanning differential electrochemical mass spectrometer (SDEMS)-scanning microscope (SECM) apparatus is described. The SDEMS used to detect and spatially resolve volatile electrochemically generated species at the surface of a substrate electrode. SECM can probe reactivity also offers convenient means leveling sample. It possible switch between these two different tips techniques without moving sample while maintaining potential control procedure for calibration tip-substrate...

Abstract Horse spleen ferritin was covalently attached to SAM‐modified gold electrodes using cross‐linking agents. Reduction of occurs at negative potentials and is electrochemically irreversible. The voltammetry reveals the presence a new electrochemical couple that has been determined be dissolved iron species released upon reduction ferritin. Covalently retains its ability release as evidenced by absence peaks when reduced in nitrilotriacetate. As SAM chain length increases, potential...

The photoluminescence and electrogenerated chemiluminescence (ECL) of 5,5′-bis(methylthio)-2,2′-bithiophene (BMTbT) have been studied compared to those 2,5-bis(methylthio)thieno[3,2-b]thiophene (f-BMTbT) 5,5′-diethyl-2,2′-bithiophene (DEbT), the fused-ring alkyl analogues BMTbT, respectively. All these compounds emitted in blue/violet region visible spectrum, with a fluorescence quantum yield ca. 0.03. In acetonitrile, BMTbT f-BMTbT each exhibited an irreversible reduction wave addition...

Microscale temperature and pH sensors, contained within an area of 125 μ m × 750 m, were fabricated on disposable 3D printed periodontal probe tips (0.5-mm diameter) with Marquis color-coded calibration marks using microfabrication electrochemical methods. The inserted in a reusable, wireless handheld electronic system that records the specific oral sites such as gingival sulcus. linear response precision each sensor tested solutions varying representing physiological range cavity. sensors...

A major goal of energy research is to use visible light cleave water directly, without an applied voltage, into hydrogen and oxygen. Since the initial reports ultraviolet (UV) activity TiO2 SrTiO3 in 1970s, researchers have pursued a fundamental understanding mechanistic molecular-level phenomena involved photo-catalysis. Although it requires UV light, after four decades still gold standard for splitting water. It chemically stable catalyzes both oxygen reactions bias. While ultrahigh vacuum...

Abstract not Available.

Thin films of iron-group metals, e.g ., Ni, Fe, and Co, their alloys oxides are interest to a wide range technical endeavors from microelectronics low cost energy storage conversion devices. For example, Ni is well-known component rechargeable battery cathodes has demonstrated superior oxygen evolution kinetics in alkaline media, making it popular catalyst for photoelectrochemical cells. Our group been investigating growth thin metal through self-terminated deposition, i.e. , wet atomic...

Development of a sustainable hydrogen economy based on water electrolysis and fuel cells is constrained by the performance, longevity high cost Pt group electrocatalysts. Important strategies for improving catalytic reactivity include alloying, forming bimetallic or alloyed surfaces, engineering substrate–catalyst interactions. At same time, significant effort underway to minimize loading metals examining new synthesis methods electrode geometries. Of particular interest atomic layer...

Metal hydroxides, oxides, and related compounds, particularly those containing Ni Fe, have received much attention for oxygen evolution reaction (OER) catalysts because they produced some of the highest reported OER rates are chemically stability in alkaline media. Electrode platforms based on Fe attractive exclude expensive precious metals, thin films these metals can be coupled with light-absorbing materials photoelectrochemical energy conversion devices used water electrolysis. Our group...

Development of a sustainable hydrogen economy based on water electrolysis and fuel cells is constrained by the performance, longevity high cost Pt group electrocatalysts. Important strategies for improving catalytic reactivity include alloying, forming bimetallic or alloyed surfaces, engineering substrate–catalyst interactions. At same time, significant effort underway to minimize loading metals examining new synthesis methods electrode geometries. Of particular interest atomic layer...

Abstract not Available.

Development of a sustainable hydrogen economy based on water electrolysis and fuel cells is constrained by the performance, longevity high cost Pt group electrocatalysts. Important strategies for improving catalytic reactivity include alloying, forming bimetallic or alloyed surfaces, engineering substrate–catalyst interactions. At same time, significant effort underway to minimize loading metals examining new synthesis methods electrode geometries. Of particular interest atomic layer...

Recently, electrodeposition of Pt and Ir was shown to exhibit an unanticipated self-terminating characteristic that enables controlled deposition monolayer thick films from simple binary electrolytes. Specifically, film growth at negative potentials is quenched by the formation a saturated layer adsorbed H, alteration double structure, in combination block adsorption metal halide precursor complex. Periodic pulsing potential desorb H sequential additional layers fabricate desired thickness...