Table 5.1. Exchange current densities and rate constants in aqueous systems

Holze, Rudolf

doi:10.1007/978-3-540-45316-1_22

Cited by 4 publications

(4 citation statements)

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“…X-ray and electron backscatter diffraction studies showed crystalline Ge grain sizes in excess of 10 –5 m, a 1000-fold increase in size relative to the results with Hg. Table summarizes some known physical properties of metals with low melting points. − The respective solubilities of Ge in Hg and Ga differ considerably at room temperature. From classical nucleation theory, the critical nucleation size of a growing crystal is a function of the solubility .…”

Section: Ec-lls Synthesis Of Crystalline Group IV Semiconductorsmentioning

confidence: 99%

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Fahrenkrug

Maldonado

2015

Acc. Chem. Res.

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This Account describes a new electrochemical synthetic strategy for direct growth of crystalline covalent group IV and III-V semiconductor materials at or near ambient temperature conditions. This strategy, which we call "electrochemical liquid-liquid-solid" (ec-LLS) crystal growth, marries the semiconductor solvation properties of liquid metal melts with the utility and simplicity of conventional electrodeposition. A low-temperature liquid metal (i.e., Hg, Ga, or alloy thereof) acts simultaneously as the source of electrons for the heterogeneous reduction of oxidized semiconductor precursors dissolved in an electrolyte as well as the solvent for dissolution of the zero-valent semiconductor. Supersaturation of the semiconductor in the liquid metal triggers eventual crystal nucleation and growth. In this way, the liquid electrolyte-liquid metal-solid crystal phase boundary strongly influences crystal growth. As a synthetic strategy, ec-LLS has several intrinsic features that are attractive for preparing covalent semiconductor crystals. First, ec-LLS does not require high temperatures, toxic precursors, or high-energy-density semiconductor reagents. This largely simplifies equipment complexity and expense. In practice, ec-LLS can be performed with only a beaker filled with electrolyte and an electrical circuit capable of supplying a defined current (e.g., a battery in series with a resistor). By this same token, ec-LLS is compatible with thermally and chemically sensitive substrates (e.g., plastics) that cannot be used as deposition substrates in conventional syntheses of covalent semiconductors. Second, ec-LLS affords control over a host of crystal shapes and sizes through simple changes in common experimental parameters. As described in detail herein, large and small semiconductor crystals can be grown both homogeneously within a liquid metal electrode and heterogeneously at the interface of a liquid metal electrode and a seed substrate, depending on the particular details chosen for ec-LLS. Third, the rate of introduction of zero-valent materials into the liquid metal is precisely gated with a high degree of resolution by the applied potential/current. The intent of this Account is to summarize the key elements of ec-LLS identified to date, first contextualizing this method with respect to other semiconductor crystal growth methods and then highlighting some unique capabilities of ec-LLS. Specifically, we detail ec-LLS as a platform to prepare Ge and Si crystals from bulk- (∼1 cm(3)), micro- (∼10(-10) cm(3)), and nano-sized (∼10(-16) cm(3)) liquid metal electrodes in common solvents at low temperature. In addition, we describe our successes in the preparation of more compositionally complex binary covalent III-V semiconductors.

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Section: Ec-lls Synthesis Of Crystalline Group IV Semiconductorsmentioning

confidence: 99%

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Fahrenkrug

Maldonado

2015

Acc. Chem. Res.

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“…To explore if the d-band center or other electrode properties explain kinetic trends of V 2+ /V 3+ and het-CT of various other transition-metal ions, we extract kinetic data for four het-CT reactions from the literature to add to our V 2+ /V 3+ work here. To avoid lab-to-lab variations in the reported k or i 0 for a redox couple on the same electrode we only compare kinetic data from the same laboratory measured using the same methods . Additionally, to control for the effect of the anion on rate constants, we only compare kinetic data in the same electrolyte.…”

Section: Resultsmentioning

confidence: 99%

“…To avoid lab-to-lab variations in the reported k or i 0 for a redox couple on the same electrode we only compare kinetic data from the same laboratory measured using the same methods. 56 Additionally, to control for the effect of the anion on rate constants, we only compare kinetic data in the same electrolyte. To ensure sufficient points to draw a correlation, we only select CT reactions where a minimum of three metals are used as electrodes.…”

Section: D-band Center As a Descriptor For Heterogeneous Inner-sphere...mentioning

confidence: 99%

Explaining Kinetic Trends of Inner-Sphere Transition-Metal-Ion Redox Reactions on Metal Electrodes

et al. 2023

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Transition-metal ions regularly undergo charge transfer (CT) by directly interacting with electrodes, and this CT governs the performance of devices for numerous applications like energy storage and catalysis. These CT reactions are deemed inner sphere because they involve direct formation of a chemical bond between the electrode and the metal ion. Predicting innersphere CT kinetics on electrodes using simple physicochemical descriptors would aid the design of electrochemical systems with improved kinetics. Herein, we report that the average energy of the d electrons (i.e., d-band center) of a transition-metal electrode rationalizes the kinetic trends of inner-sphere CT of transitionmetal ions. We demonstrate that V 2+ /V 3+ , an important redox reaction for flow batteries, is an inner-sphere reaction and that the kinetic parameters correlate with the adsorption strength of the vanadium intermediate on Au, Ag, Cu, Bi, and W electrodes, with W being the most active electrode reported to date. We show that the adsorption strength of the vanadium intermediate linearly correlates with the d-band center such that the d-band center serves as a simple descriptor for the V 2+ /V 3+ kinetics. We extract kinetic data from the literature for four other inner-sphere CT reactions of metal ions involving Cr-, Fe-, and Co-based complexes to show that the d-band center also linearly correlates with kinetic trends for these systems. The d-band center of the electrode is a general descriptor for heterogeneous inner-sphere CT because it correlates with the adsorption strength of the metal-ion intermediate. The d-band center descriptor is analogous to the d-electron configuration of metal ions serving as a descriptor for homogeneous inner-sphere CT because the d-electron configuration controls bond strengths of intermediate metal-ion complexes.

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“…It is however difficult to choose a metal purely based on published values of j 0 as this quantity strongly depends on the properties of the solution. However, bearing in mind that cerebrospinal fluid is a solution composed mainly of H 2 O and a small concentration of NaCl we can use published j 0 values [11] for hydrogen evolution reaction in a small concentration H 2 SO 4 solution. Comparing values against j 0 of Pt, a material typically used for neural microwires for its advantageous chemical properties, it can be seen that Niobium (Nb) typically has j 0 4 orders of magnitude smaller than Pt.…”

Section: A Electrode Materials Suitabilitymentioning

confidence: 99%

Microwire-CMOS integration of mm-scale neural probes for chronic local field potential recording

Szostak

Mazza

Maslik

et al. 2017

2017 IEEE Biomedical Circuits and Systems Conference (BioCAS)

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Abstract-This paper proposes a novel method for integrating CMOS microelectronics with microwire-based electrodes for next generation implantable brain machine interfaces. There is strong evidence to suggest that microwire-based electrodes outperform micromachined and polymer-based electrodes in terms of signal integrity and chronic viability. Furthermore, it has been shown that the recording of Local Field Potentials (LFPs) is more robust to tissue damage and scar tissue growth when compared to action potentials. This work therefore investigates the suitability of microwire electrodes for LFP recording by studying the electrical properties of key materials. We identify Niobium (Nb) as a candidate material with highly desirable properties. There is however also an inherent incompatibility when it comes to connection of microwire-based electrodes to silicon chips. Here we present a new process flow utilising a recessed glass substrate for mechanical support, silicon interposer for interconnection, and electroplating for contact adhesion. Furthermore, the proposed structure lends itself to hermetic encapsulation towards gas cavity based micropackages.

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Table 5.1. Exchange current densities and rate constants in aqueous systems

Cited by 4 publications

References 261 publications

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Electrochemical Liquid–Liquid–Solid (ec-LLS) Crystal Growth: A Low-Temperature Strategy for Covalent Semiconductor Crystal Growth

Explaining Kinetic Trends of Inner-Sphere Transition-Metal-Ion Redox Reactions on Metal Electrodes

Microwire-CMOS integration of mm-scale neural probes for chronic local field potential recording

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