Polarographic Studies on the Oxidation and Hydrolysis of Sodium Borohydride<sup>1</sup>

Pecsok, Robert L.

doi:10.1021/ja01108a021

Cited by 99 publications

(68 citation statements)

References 2 publications

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“…Using the chaotic mixers described in Section F, mass transport to the electrodes tripled, in agreement with our theoretical predictions, 30 and therefore tripled our transport-limited current density to nearly 0.5 A/cm 2 . However, because more voltage had to be sacrificed to drive reaction rates faster to support this current density, via Butler-Volmer kinetics, 28 4 -/ CAN system, it would produce 0.5 W/cm 2 under laminar flowIn our proposed work, we aim to stabilized BH 4 -out toward its solubility limit (14 M) and reduce the internal resistance of our planar FC.…”

Section: Esupporting

confidence: 71%

“…Previously, it was determined that VO 2 + would slowly poison Au cathodes, 20 but we discovered that occasionally pulsing the electrode to high potentials (> +0.6 V vs. Ag/AgCl, 0.5 M H 2 SO 4 ) would remove surface-bound poisons and fully restore current density in a manner analogous to our findings with BH 4 -. ClO -has only recently appeared as a fuel cell oxidant, 21,22 and we were understandably skeptical of its effectiveness.…”

Section: +supporting

confidence: 65%

“…Indeed, we found Cr 2 O 7 2-'s kinetics to be immeasurably fast by RDE methodology, with RDE voltammograms appearing as, essentially, step functions instead of smooth waves (Figure 14). Like CAN, reduction of Cr 2 O 7 2-does not appear to have any poisoning or adverse side reactions, and we were able to observe sustained current densities > 0.4 A/cm 2 , specific surface area, for 20 min. Because Cr 2 O 7 2-accepts 6 times the number of e -as CAN, and has a diffusion coefficient about twice as large, its current density is nearly ten times greater (Figure 14 vs.…”

Section: Dmentioning

confidence: 70%

“…1,2 Hydrolysis can proceed partially or completely, converting any number of BH 4 -'s eight reducing equivalents to H 2 or partial fractions thereof. Hydrolysis occurs readily in bulk solution, in both acidic and neutral aqueous environments, as well as at the surfaces of various catalysts.…”

mentioning

confidence: 99%

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Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Abruña

2013

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Abstract:Our work is focused on membraneless laminar flow fuel cells, an unconventional fuel cell technology, intended to create a system that not only avoids most typical fuel cell drawbacks, but also achieves the highest power density yet recorded for a non-H 2 fuel cell. We have employed rigorous electrochemistry to characterize the high-energydensity fuel BH 4 -, providing important mechanistic insight for anode catalyst choice and avoiding deleterious side reactions. Numerous fuel cell oxidants, used in place of O 2 , are compared in a detailed, uniform manner, and a powerful new oxidant, cerium ammonium nitrate (CAN), is described. The high-voltage BH 4 -/CAN fuel/oxidant combination is employed in a membraneless, room temperature, laminar-flow fuel cell, with herringbone micromixers which provide chaotic-convective flow which, in turn, enhances both the power output and efficiency of the device. We have also been involved in the design of a scaled-up version of the membraneless laminar flow fuel cell intended to provide a 10W output. Research FindingsA.Electroanalytical investigation of borohydride (BH 4 -): Oxidation mechanism, best catalysts, and performance optimization.Our search for a highly soluble fuel for microfluidic fuel cell applications quickly focused on BH 4 -, most commonly used as its sodium salt, NaBH 4 . This compound has considerable solubility in aqueous solutions (>14 M), a high electron recovery per molecule (8e -, Reaction 1), a very low potential for oxidation in base (-1.44 V vs. Ag/AgCl), and extremely fast kinetics at room temperature:Thus, it has approximately the same low onset potential for oxidation as H 2 , allowing for high voltage systems. However, because of its very high solubility, about 14,000 times that of H 2 , it can have a theoretical maximum current density that is multiple orders of Reaction E°' (V vs. Ag/AgCl, 1M NaOH)

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Section: Esupporting

confidence: 71%

Section: +supporting

confidence: 65%

Section: Dmentioning

confidence: 70%

mentioning

confidence: 99%

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Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Abruña

2013

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“…The degree of uncertainty in estimating k' could, in some cases, be relatively high. This uncertainty is due both to the contributions of the single experi- [69][70][71][72]. The only exceptions are the studies by Jolly and coworkers [60,64].…”

Section: Acid-catalyzed Hydrolysis Of Borane Complexesmentioning

confidence: 89%

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

D’Ulivo

Dědina

Mester

et al. 2011

Pure and Applied Chemistry

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Aqueous-phase chemical generation of volatile hydrides (CHG) by derivatization with borane complexes is one of the most powerful and widely employed methods for determination and speciation analysis of trace and ultratrace elements (viz. Ge, Sn, Pb, As, Sb, Bi, Se, Te, Hg, Cd, and, more recently, several transition and noble metals) when coupled with atomic and mass spectrometric detection techniques. Analytical CHG is still dominated by erroneous concepts, which have been disseminated and consolidated within the analytical scientific community over the course of many years. The overall approach to CHG has thus remained completely empirical, which hinders possibilities for further development. This report is focused on the rationalization and clarification of fundamental aspects related to CHG: (i) mechanism of hydrolysis of borane complexes; (ii) mechanism of hydrogen transfer from the borane complex to the analytical substrate; (iii) mechanisms through which the different chemical reaction conditions control the CHG process; and (iv) mechanism of action of chemical additives and foreign species. Enhanced comprehension of these different mechanisms and their mutual influence can be achieved in light of the present state of knowledge. This provides the tools to explain the reactivity of a CHG system and contributes to the clarification of several controversial aspects and the elimination of erroneous concepts in CHG.

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Hydrogen Generation—Homogeneous

Laurenczy

2010

Encyclopedia of Catalysis

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Today industrial hydrogen production is dominated by processes based on heterogeneous catalysts, using fossil fuels as H 2 sources. However, homogeneous catalysts are becoming more popular in the generation of H 2 for hydrogen storage, delivery, and in mobile/on‐site or small volume hydrogen applications. Generally for these applications, the H 2 gas produced should be pure (eg, no CO contamination), the hydrogen generation should take place under mild conditions, and the H 2 supply unit should be small. Most notably, research into homogeneous catalysis has focused on the chemical storage/delivery systems, based on sodium borohydride, ammonia‐borane, hydrocarbons/alcohols, and formic acid. In the HCOOHCO 2 , cycle the greenhouse carbon dioxide gas is used as the hydrogen vector. The use of solar energy in homogeneous catalytic H 2 gas production from water and from other hydrogen sources is the subject of extensive studies. A direct photochemical process converts solar energy into hydrogen much more efficiently than the two‐step electricity–water electrolysis/H 2 gas route.

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Polarographic Studies on the Oxidation and Hydrolysis of Sodium Borohydride¹

Cited by 99 publications

References 2 publications

Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

Hydrogen Generation—Homogeneous

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Polarographic Studies on the Oxidation and Hydrolysis of Sodium Borohydride1

Cited by 99 publications

References 2 publications

Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Transport Phenomena and Interfacial Kinetics in Planar Microfluidic Membraneless Fuel Cells

Mechanisms of chemical generation of volatile hydrides for trace element determination (IUPAC Technical Report)

Hydrogen Generation—Homogeneous

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Polarographic Studies on the Oxidation and Hydrolysis of Sodium Borohydride¹