Oxygen reduction mechanism on copper in a 0.5 M H2SO4

doi:10.1016/j.electacta.2009.02.019

Electrochimica Acta

Volume 54, Issue 15, 1 June 2009, Pages 3972-3978

https://doi.org/10.1016/j.electacta.2009.02.019 Get rights and content

Abstract

The mechanism of the oxygen reduction reaction (ORR) in a naturally aerated stagnant 0.5 M H₂SO₄ was studied using electrochemical methods. The cathodic polarization curve showed three different regions; electrochemical impedance spectroscopy (EIS) measurement was used accordingly. The EIS data were analyzed, and the mechanism for the ORR was proposed consequently. The three regions include a limiting current density region with the main transfer of 4e⁻ controlled by diffusion (−0.50 V < E < −0.40 V), a combined kinetic-diffusion region (−0.40 V < E < −0.20 V) with an additional 2e⁻ transfer due to the adsorption of the anions, and a hump phenomenon region (−0.20 V < E < −0.05 V), in which the chemical redox between the anodic intermediate $Cu {(I)}_{ads}^{*}$ and the cathodic intermediate ${(H O_{x})}_{ads}^{*}$ , together with the electrochemical reaction, synergistically results in the acceleration of the ORR. Therefore, a coupled electrochemical/chemical process (the EC mechanism) in the hump phenomenon region was proposed, and a good agreement was found between the experimental and fitted results. The EC mechanism was confirmed by the deaerated experiments.

Introduction

Copper and its alloys are used extensively in many types of chemical equipment and industries [1], [2]. Moreover, their application frequently involves acidic solutions and dissolved oxygen. Generally, except under high cathodic overpotentials, copper does not displace hydrogen, and the presence of dissolved oxygen is essential for its cathodic reduction [3], [4], [5]. Therefore, it is important to investigate the mechanism of the oxygen reduction reaction (ORR) on copper in acidic solutions, and a lot of work has been done in this regard [5], [6], [7], [8], [9].

The reduction of oxygen may occur via a 4e⁻ (Eq. (1)), a 2e⁻ (Eq. (2)), or a mixed process that combines these two limiting cases [10], [11].O₂+4H⁺+4e⁻ → 2H₂OO₂+2H⁺+2e⁻ → H₂O₂

Eqs. (1), (2) involve many elementary reactions and are strongly influenced by potential [11]. Moreover, they generally relate to the electrode surface state and the adsorption of the anions; additionally, they may be catalyzed by the cuprous species in the medium [12], [13], [14], [15], [16]. The pathway of the ORR and the specific adsorption of the anions on polycrystalline and single crystalline copper surfaces in H₂SO₄ have been investigated by electrochemical and spectroscopic analysis techniques [4], [7], [8], [9], [17], [18], [19], [20]. However, the influence of the anodic reaction is usually neglected in the investigation except when considering the catalytic effect from the cuprous species. Furthermore, some researchers have found and explained the hump phenomenon on copper in H₂SO₄ near the corrosion potential [12], [21], [22], which exerts a strong influence on the corrosion rate and inhibition efficiency. However, the mechanism of the ORR remains the subject of some uncertainty and dispute [4], [7], [22], [23], and a comprehensive and thorough investigation is necessary.

The EIS method has been successfully used to study the anodic and cathodic reaction mechanisms of the metal [21], [22], [24], [25], [26], [27], [28]. It is useful in deriving quantitative kinetic information on the electrode surface [29], [30], [31]. In our work, the polarization curve was measured to determine the general characteristics of the ORR. EIS measurements were used in a wide frequency range and at different potentials from −0.50 to −0.05 V (vs. SCE) on copper in naturally aerated stagnant 0.5 M H₂SO₄. At the same time, the data were analyzed using appropriate equivalent circuits, and the influence of the anodic reaction was considered. Finally, kinetic information and the mechanism of the ORR were obtained, and a kinetic model describing the hump phenomenon was proposed. In contrast with that, some deaerated experiments were done to expect to confirm the propositional mechanism.

Section snippets

Experimental

The electrochemical measurements were conducted in a three-electrode cell at room temperature (20 °C) via a PowerSuite Electrochemical Interface. The working electrode was prepared from a polyurethane-coated copper wire. Prior to an experiment, the polycrystalline copper wire was dipped in a hot 98 wt% H₂SO₄ solution for several minutes to remove the coating, yielding a bare glassy pure copper wire (99.9%) with a diameter of 1.64 mm. Its tip and area around the water line were enclosed with

Polarization measurement

The potentiodynamic polarization curves in naturally aerated (solid line) and deaerated (dashed line) stagnant 0.5 M H₂SO₄ are shown in Fig. 1. In order to thoroughly consider the mechanism of the ORR on copper in naturally aerated stagnant 0.5 M H₂SO₄, we divided the cathodic part into three regions according to the different characteristics. Region I (−0.50 V < E < −0.40 V) refers to oxygen diffusion limiting current at high cathodic overpotentials; Region II (−0.40 V < E < −0.20 V) represents a mixed

Conclusion

The mechanisms of the cathodic ORR were investigated in a naturally aerated stagnant 0.5 M H₂SO₄: (1) The main process involved 4e⁻ process controlled by diffusion at −0.50 to −0.40 V; (2) A combined kinetic-diffusion controlled process appears at −0.40 to −0.20 V, with a 2e⁻ transfer instead of 4e⁻ due to the adsorption of the (bi)sulfate anion; (3) A hump phenomenon appears at −0.20 to −0.05 V, and a synergistic EC mechanism is proposed; i.e., the chemical redox between the anodic intermediate $Cu ($

Acknowledgement

The authors gratefully acknowledge the help rendered by the National Natural Science Foundation of China under Contact 50671097.

References (40)

A.G. Zelinsky et al.
Corros. Sci.
(2004)
T. Jiang et al.
Electrochim. Acta
(2007)
H.Y. Ma et al.
Corros. Sci.
(2003)
G. Brisard et al.
J. Electroanal. Chem.
(2000)
V.N. Vesovic et al.
J. Electroanal. Chem.
(1987)
D. Pletcher et al.
J. Electroanal. Chem.
(1993)
E. Yeager
Electrochim. Acta
(1984)
M.H. Ghandehari et al.
Corros. Sci.
(1976)
E.J. Calvo et al.
J. Electroanal. Chem.
(1988)
F. King et al.
J. Electroanal. Chem.
(1995)

M. Wilms et al.

Surf. Sci.

(1998)

G.M. Brown et al.

J. Electroanal. Chem.

(1995)

M. Wilms et al.

Surf. Sci.

(1998)

J.W. Schultze et al.

Electrochim. Acta

(1987)

O.E. Barcia et al.

Electrochim. Acta

(1990)

M.R.F. Hurtado et al.

Electrochim. Acta

(2003)

Y.L. Cheng et al.

Corros. Sci.

(2004)

D.B. Zhou et al.

Electrochim. Acta

(1995)

J.B. Matos et al.

J. Electroanal. Chem.

(2004)

G.G.O. Cordeiro et al.

Electrochim. Acta

(1993)

Cited by (39)

Amine and Carbon-pretreated nickel–molybdenum disulfide as bifunctional electrocatalysts for hydrogen and oxygen gas evolution
2022, International Journal of Hydrogen Energy
Citation Excerpt :
The aggregation of MoO3 may cover the electrode surface and the formation of nickel hydroxide species may render a slight decrease in current density [40]. The specific capacitance values for a variety of metal electrodes in acidic or alkaline solutions have been reported with a range between 0.015 and 0.110 mF/cm2 in H2SO4 [44] and 0.022–0.130 mF/cm2 in NaOH [45] and KOH [46] aqueous solutions. For the determination of ECSA in our electrocatalytic system, we accept Cs = 0.035 mF/cm2 in 0.5 M H2SO4 and Cs = 0.040 mF/cm2 in 1.0 M KOH solution based on the reported value for the evaluation of catalysts performing HER and OER.
We report the synthesis and characterization of a variety of nickel molybdenum disulfide (NiMoS₂) materials as efficient bifunctional electrocatalysts for both the hydrogen evolution and oxygen evolution reactions (HER and OER, respectively). These catalysts were obtained from pretreated ammonium tetrathiomolybdate (ATM) using ethylenediamine (EDA), diethylenetriamine (DETA), or carbon nanotubes (CNT), which were further reacted with Ni(NO₃)₂. All the materials were characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (pXRD), and all materials were evaluated as both HER and OER electrocatalysts. The NiMoS₂ synthesized from DETA-pretreatment exhibits the best HER catalytic performance with the lowest overpotential of 0.151 V, while the CNT-modified NiMoS₂ shows the lowest OER overpotential of 0.310 V. All the pretreated NiMoS₂ electrocatalysts show significantly improved catalytic activity compared to the one prepared directly from pristine ATM precursor.
Influence of copper surface pretreatment on the kinetics of oxygen reduction reaction in 0.5 M NaCl solution: Surface characterization and electrochemical studies
2021, Applied Surface Science Advances
Citation Excerpt :
It is interesting to note that the number of electrons exchanged is slightly increasing as the potential becomes more negative. As reported by previous ORR studies [37,38], the surface is considered to be free of oxide which facilitates the co-adsorption and the breakage of the OO bond of oxygen molecules. Passivated surface: Fig. 12 illustrates the influence of electrode rotation rate on the polarization curves recorded on a passivated copper surface in aerated 0.5 M NaCl.
The study of oxygen reduction reaction (ORR) in 0.5 M NaCl on copper revealed that oxygen reduction reaction rates are markedly influenced by the surface condition and increased in the following order: covered with PDTC < pre-reduced < passivated surfaces. On pre-reduced and passivated surfaces, the ORR proceeded via a four electron pathway limited by oxygen diffusion. When the surface is passivated, the ORR is influenced by a combination of the reduction of copper oxide and the normal kinetics of ORR at a pre-reduced surface. The partial reduction of Cu₂O oxide enhances the ORR kinetics. A surface covered with PDTC represents the least reactive site towards ORR process. The current densities decreased significantly due to the limitation of O₂ access to the surface by the formation of a protective barrier layer. PDTC molecules are bonded on copper surface and form an inhibitive adsorption layer, which plays a major role in slowing down O₂ reduction by blocking the active cathodic sites.
Nitrite effects on copper corrosion in nitric acid solutions
2021, Corrosion Science
The proposed long term management plan for Canadian spent nuclear fuel is to seal it in copper-coated steel containers and bury it in a deep geologic repository. During the early period after emplacement, the container could be exposed to a humid, aerated, and irradiated environment containing nitric acid. The corrosion of copper was studied in aerated and de-aerated nitrate solutions with emphasis on the influence of nitrite produced by nitrate reduction. Using various electrochemical and surface analytical techniques nitrite was shown to compete with nitrate for surface adsorption sites and, if present at sufficient concentrations, cause rapid corrosion of copper.
In situ investigation of atmospheric corrosion behavior of copper under thin electrolyte layer and static magnetic field
2020, Microelectronics Reliability
Citation Excerpt :
The magnetic line of flux is just perpendicular to the direction of ions migration and the hindrance effect of Lorentz force on ion motion is the most significant. Lorentz force changes the ion trajectory from approximately linear to divergent spiral in the diffusion layer [15]. Lorentz force reduces the normal migration velocity of ions along the electrode surface and the number of ions close to electrode surface, correspondingly, less electrochemical reactions would take place on the electrode surface.
The effect of static magnetic field on atmospheric corrosion behavior of copper under thin electrolyte layer is investigated through polarization curves, electrochemical impedance spectroscopy, EDS and SEM techniques. The influences of the intensity and direction of magnetic field on the corrosion behavior are discussed. Results show that: mainly pitting corrosion occurs to the copper; the magnetic field reduces the ability of ions to migrate from thin electrolyte layer to electrode surface, and inhibits the formation of CuO and soluble copper chloride. The mechanisms involved are proposed to explain the inhibition effect.
Two-dimensional transition-metal dichalcogenides for electrochemical hydrogen evolution reaction
2019, FlatChem
In this review, we comprehensively review some recent progress of two-dimensional (2D) transition-metal dichalcogenides (TMDs) in the application of hydrogen evolution reaction (HER), for the purpose of offering a reference for related researchers, especially for new beginners in this research field. The mechanism of HER is first presented in detail, followed by an introduction of evaluation methods and some considerations in HER tests. Then, we make a brief description of composition, structure and crystal phases of TMDs. Next, we highlight the intrinsic factors determining HER performance and summarize the recent development of strategies for improving the HER performance of TMDs. At last, an overall summary is presented and important challenges are discussed as well.
Electrochemical properties of Pb-0.6 wt% Ag powder-pressed alloy in sulfuric acid electrolyte containing Cl<sup>−</sup>/Mn<sup>2+</sup> ions
2018, Hydrometallurgy
In this study, Pb-0.6 wt% Ag powder-pressed alloy was fabricated and used as an insoluble anode for zinc electrowinning. The micromorphology, phase composition and elements distribution of the oxide layer formed on Pb-0.6 wt% Ag anode were studied. Additionally, the anodic reaction process, galvanostatic potential and oxygen evolution kinetics in Cl⁻/Mn²⁺ ions containing sulfuric acid electrolyte were investigated. Compared with the traditional Pb-0.6 wt% Ag cast-rolled alloy, Pb-0.6 wt% Ag powder-pressed alloy shows much lower anodic potential, self-corrosion current density, cell voltage and higher exchange current density in the same electrolyte. Due to a thin and uniform MnO₂ layer formed on the surface of powder-pressed alloy with the presence of Mn²⁺ ion in the electrolyte, the powder-pressed alloy presents a stable anodic potential. Consequently, the corrosion of powder-pressed Pb-0.6 wt% Ag anode was suppressed and the anode slime was decreased compared with Pb-0.6 wt% Ag cast-rolled anode.

View all citing articles on Scopus

View full text