Electrochemical Oxidation Of Cu Research Articles

Fabrication and characterization of extrinsic electrochemically modified graphite reinforcement carbon paste electrode for selective determination of Cu(II) in trace levels

An electrochemical oxidation of copper species has been successfully performed by using electrochemically modified 8‑hydroxy quinoline graphite reinforcement carbon paste electrode; in other words, quinolyl graphite reinforcement Carbon paste electrode (Q/GRCPE). Scanning electron microscopy (SEM) was used for the morphological characterization of the electrode before the modification and after modification and utilization. Under the optimal conditions of cyclic voltammetry (CV) and square wave adsorptive anodic stripping voltammetry (SWAdASV), the electrochemical oxidation of Cu(II) can be investigated. The performance of the electrochemically modified sensor was systematically studied. The experimental data suggested that the electrochemically modified sensor exhibited excellent catalytic activity for the electrochemical oxidation of Cu(II) with a detection limit (LOD) 2.1 × 10−11 M. The application of the electrochemically modified sensor for the detection of Cu(II) in Tap water (TW), ground water (GW) and Nile River water (NRW) showed good recovery with reproducible results. The peak currents of Cu(II) were evaluated within a wide concentration range, in favor of more durability, sensitivity, and selectivity which suitable for investigation of real samples. It was shown that the proposed electrochemically modified Q/GRCPE proved to be a cheap "pre- alarm" tool for rapid determining of Cu(II) in environmental water samples even in the presence of some interfering ions. The adsorptive accumulation of Cu(8-HQ)2, approaches results in an effective preconcentration of Cu(II) with short adsorption time (30 s).

Electrochemical copper dissolution: A benchmark for stable CO2 reduction on copper electrocatalysts

Copper is well known in fundamental electrocatalysis research due to its ability to selectively reduce CO2 to C2 products. Recent, more applied studies have revealed that electrolyzers based on Cu electrocatalysts can reach current densities of up to hundreds of mA cm−2. This opens up the opportunity for industrial application of Cu-based electrocatalysts. However, the stability of copper must first be assessed. In this communication we investigate the electrochemical corrosion behavior of copper in a broad pH window relevant to CO2 reduction applications. Using an electrochemical on-line inductively coupled plasma mass spectrometer (ICP-MS), we quantify Cu dissolution during anodic oxidation and during the reduction of electrochemically formed oxide species. We show that electrochemical oxidation of Cu leads to high dissolution in neutral and highly alkaline environments, while an intermediate pH of around 9–10 leads to minimal dissolution. The obtained results are discussed in relation to the CO2 reduction reaction to set a benchmark for stable Cu-based electrocatalysts.

In Situ Electrochemical Oxidation of Cu2S into CuO Nanowires as a Durable and Efficient Electrocatalyst for Oxygen Evolution Reaction

Development of cost-effective oxygen evolution catalysts is of capital importance for the deployment of large-scale energy-storage systems based on metal–air batteries and reversible fuel cells. In...

Early Stages of Electrochemical Oxidation of Cu(111) and Polycrystalline Cu Surfaces Revealed by in Situ Raman Spectroscopy

Investigating the chemical nature of the adsorbed intermediate species on well-defined Cu single crystal substrates is crucial in understanding many electrocatalytic reactions. Herein, we systematically study the early stages of electrochemical oxidation of Cu(111) and polycrystalline Cu surfaces in different pH electrolytes using in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS). On Cu(111), for the first time, we identified surface OH species which convert to chemisorbed "O" before forming Cu2O in alkaline (0.01 M KOH) and neutral (0.1 M Na2SO4) electrolytes; while at the Cu(poly) surface, we only detected the presence of surface hydroxide. Whereas, in a strongly acidic solution (0.1 M H2SO4), sulfate replaces the hydroxyl/oxy species. This results improves the understanding of the reaction mechanisms of various electrocatalytic reactions.

Tuning and Probing the Distribution of Cu+ and Cu2+ Trap States Responsible for Broad-Band Photoluminescence in CuInS2 Nanocrystals.

The processes that govern radiative recombination in ternary CuInS2 (CIS) nanocrystals (NCs) have been heavily debated, but recently, several research groups have come to the same conclusion that a photoexcited electron recombines with a localized hole on a Cu-related trap state. Furthermore, it has been observed that single CIS NCs display narrower photoluminescence (PL) line widths than the ensemble, which led to the conclusion that within the ensemble there is a distribution of Cu-related trap states responsible for PL. In this work, we probe this trap-state distribution with in situ photoluminescence spectroelectrochemistry. We find that Cu2+ states result in individual “dark” nanocrystals, whereas Cu+ states result in “bright” NCs. Furthermore, we show that we can tune the PL position, intensity, and line width in a cyclic fashion by injecting or removing electrons from the trap-state distribution, thereby converting a subset of “dark” Cu2+ containing NCs into “bright” Cu+ containing NCs and vice versa. The electrochemical injection of electrons results in brightening, broadening, and a red shift of the PL, in line with the activation of a broad distribution of “dark” NCs (Cu2+ states) into “bright” NCs (Cu+ states) and a rise of the Fermi level within the ensemble trap-state distribution. The opposite trend is observed for electrochemical oxidation of Cu+ states into Cu2+. Our work shows that there is a direct correlation between the line width of the ensemble Cu+/Cu2+ trap-state distribution and the characteristic broad-band PL feature of CIS NCs and between Cu2+ cations in the photoexcited state (bright) and in the electrochemically oxidized ground state (dark).

Enhancement of electrochemical oxidation of Cu(CN) 3 2− by the peroxydisulfate oxidation

Abstract In this work, the peroxydisulfate (PDS/K 2 S 2 O 8 ) enhancement of electrochemical oxidation of Cu(CN) 3 2− with the RuO 2 /Ti mesh anode and the stainless steel cathode was investigated. The removal efficiency of cyanide was largely increased with increasing the PDS concentration. When the concentration of K 2 S 2 O 8 was 1.00 mM and the current density was 14.80 A/m 2 , the removal efficiency of cyanide was increased from 34.3% to 89.1% at the initial 10 min. The Cu mass distribution onto the cathode, in the solution, and onto the anode was investigated. With the increase of K 2 S 2 O 8 concentration, the mass of Cu oxides deposition on the anode surface was increased. Combined with the SEM-EDS, XRD and XPS analysis for the anode surface, it was confirmed that the generation of deposition on the anode surface was CuO. The generation of sulfate and hydroxyl radicals was confirmed by the ESR analysis. It was suggested that Cu(I) reacted with S 2 O 8 2− via a Fenton-like process, leading to the formation of SO 4 - radical. OH radical was generated due to the reaction between SO 4 - and OH − /H 2 O. Therefore, these active radicals and anode oxidation were responsible for cyanide removal.

Voltammetric determination of ascorbic acid by using a disposable screen printed electrode modified with Cu(OH)2 nanorods

The authors describe a disposable non-enzymatic sensor for ascorbic acid (AA) that was obtained by modifying a screen printed electrode (SPE) with Cu(OH)2 nanorods (NRs). The NRs were synthesized by a wet chemical process which involves sequential addition of NH3 and NaOH to CuSO4 solution. NR formation was confirmed by thermogravimetric, spectroscopic, microscopic, and diffraction studies. The Cu(OH)2 NRs were mixed with carbon ink and printed onto an SPE. Electrochemical detection of AA was carried out at pH 7.4, at a typical voltage as low as 0 mV versus saturated calomel electrode with a scan rate of 100 mV/s, and is assumed to involve the chemical reduction of Cu(II) by AA followed by electrochemical oxidation of Cu(I). The sensor has a linear response in the 0.0125 to 10 mΜ AA concentration range. Response to AA is free from interference by urea, glucose, uric acid, dopamine, metal ions such as Fe2+, Zn2+ and Ni2+, NaCl, KCl and ethanol. It was applied to the determination of AA in a vitamin C tablet and in urine.

Direct Electrochemical Synthesis and Crystal Structure of Copper(I) Complex with 2′‐hydroxy‐5′‐methyl‐acetophenone and Triphenylphosphine Ligands

A new complex of Cu with 2′‐hydroxy‐5′‐methyl‐acetophenone (HMAP) and triphenylphosphine (PPh3) was prepared by the electrochemical oxidation of Cu in acetonitrile solutions. The final product, (MAP)Cu(PPh3)2, was crystallized from bulk solution and characterized by microanalysis, IR, Raman, 1H NMR together with x‐ray crystallographic determinations. The results showed that the complex was a chelate structure in which Cu(I) ion was coordinated with two oxygen atoms of the deprotonated ligand of MAP anion to form a six member ring, and two PPh3 molecules participated in the coordination. The parameters of the complex were monoclinic, space group of P21/n, a=9.048(2) Å, b=26.405(6) Å, c=15.606(4) Å, β=95.990(5)°, Z=4, R=0.057 for 8428 unique reflections. The details of synthesis, reaction mechanism on the electrode and the effect of PPh3 on the coordinating processes are discussed.

Improving photocatalytic activity of Cu-loaded TiO 2 film using a pulse anodic bias

The application of a small anodic bias can promote the photocatalytic oxidation of formic acid on Cu–TiO 2 film. However, the photocatalytic activity was not stable at higher anodic biases or in the process of repeated use due to the electrochemical oxidation of Cu. A new photocatalytic technology with a pulse anodic bias was proposed to tackle the deficiency of the Cu–TiO 2 film. It was found that the photocatalytic technology could not only overcome the Cu oxidation but also increased the photocatalytic activity of the Cu–TiO 2 film.

ChemInform Abstract: Direct Electrochemical Synthesis of Copper and Silver Derivatives of Alkanedithiols and Crystal Structure of (Cu2S2C3H6‐1,2·(C6H5)2PCH2P(C6H5)2)4·4 CH3CN.

AbstractThe electrochemical oxidation of Cu or Ag in solutions of various sym. or asym.