Mechanism of Electrochemical Reduction of Hydrogen Peroxide on Copper in Acidic Sulfate Solutions
ABSTRACT Hydrogen peroxide is a commonly used oxidizer component in chemical mechanical planarization slurries, used in the processing of Cu metallization in microelectronics applications. We studied the electrochemical reduction of hydrogen peroxide on Cu in 0.1 M H2SO4 solutions using methods including cyclic voltammetry, rotating disk electrode experiments, surface-enhanced Raman spectroscopy, and density functional theory (DFT) calculations. The spectroscopy reveals that the hydrogen peroxide molecule is reduced at negative potentials to form a Cu-OH surface species in acidic solutions, a result consistent with the insight from Tafel slope measurements. DFT calculations support the instability of peroxide relative to the surface-coordinated hydroxide on both Cu(111) and Cu(100) surfaces.
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- "Recently, it is clearly recognized that nitrate pollution of water sources is a huge problem for the society. Several techniques have been proposed for the efficient removal of nitrate, but such applications are limited by their expensive cost     . On the other hand several methods such as spectrophotometry, chromatography and electrochemistry have been used for nitrate reduction or sensing . "
ABSTRACT: This study examines the synthesis and characterization of polypyrrole coated palladium nanocluster (Pd NCs-PPy) composites and their application in nitrate detection at pH = 7.0. The synthesis was performed via the direct reduction of an aqueous solution of Pd (CH3COO)2 in the presence of pyrrole monomers in NaOH. X-ray diffraction and field emission scanning electron microscopy observations showed that the Pd cations were completely reduced to Pd with the formation of Pd NCs-PPy cluster morphology, respectively. Electrochemical properties of the Pd NCs-PPy electrode were studied by differential pulse voltammetry (DPV), cyclic voltammetry and electrochemical impedance spectroscopy. From the DPV results, the estimated limit of detection, limit of quantification (S/N = 3) for the two linear segments (lower and higher concentration of nitrate) are 0.7444, 2.4815 and 0.4535, 1.5117 μM, respectively. The sensitivity of these two linear segments is 0.124 and 0.204 μA μM−1 cm−2, respectively. Results from the reproducibility experiments show that the Pd NCs-PPy is feasible for the quantitative determination of certain concentration ranges of nitrate.08/2015; 751. DOI:10.1016/j.jelechem.2015.05.026
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- "Pt is also the most commonly used cathode electrocatalyst for DBFCs . Additionally, Pd , Pd-Ir , Pd-Ag , Pd-Pt , Pd-Ru , CuO/Nafion/Pt , Cu , Au  and Prussian blue modified electrodes  have been studied as cathode materials for H2O2 electroreduction. "
ABSTRACT: Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.12/2012; 2(3):478-92. DOI:10.3390/membranes2030478
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ABSTRACT: Chemical mechanical planarization/polishing (CMP) of copper has emerged as an important component in semiconductor processing. It involves both chemical and mechanical effects, consisting of several steps such as passivation, film dissolution, chemical corrosion, and abrasive abrasion. It is important to understand the individual steps in the removal process. In this paper, investigations were focused on the tribo-chemical behavior of copper in hydrogen peroxide solution at different pH values. The repassivation current and friction coefficient were measured in situ as a function of time. The compositions of unworn and worn surfaces after the tribocorrosion experiments were also analyzed by Raman spectra. The copper exhibited a tendency of repassivation during the potentiostatic tests; furthermore, the repassivation kinetics varied with the surface species and the quantity of passive films formed at different pH values. The results indicate that both relatively high material removal rate and good surface quality may be achieved in the weak acidic solution during CMP.Tribology Letters 05/2013; 50(2). DOI:10.1007/s11249-013-0110-5 · 2.15 Impact Factor