Catalytic effect of l-proline on the reduction of Ni(II) ions during nickel electrodeposition from a Watts-type nickel bath
N.F. El Boraei; Ibrahim, Magdy;
Abstract
Many chemical entities have been proposed as additives to enhance the properties and
structure of electrodeposited nickel. In this work, considerable improvements have
been found by using L-proline as a complexing agent in a Watts-type nickel bath.
This study determined the influence of L-proline concentrations on the cathodic
efficiency, cathodic polarization, anodic linear stripping voltammetry, current-time
transients, macrothrowing power and Wagner number. The presence of L-proline
leads to a great shift in the polarization curve and the deposition potential towards
more noble potentials, indicating the catalytic effect of L-proline on the reduction of
Ni(II) ions. The kinetic data confirmed that the exchange current density is greatly
enhanced with increasing L-proline concentration. The Tafel slopes in the presence of
L-proline are higher (141–160 mV decade−1) than that without L-proline (130.7 mV
decade−1). The constant values of αc, proposes that the Ni electrodeposition
mechanism is not influenced by the presence of L-proline. The corrosion property of
nickel coatings prepared from Watts-type nickel bath in the absence and presence of
L- proline was tested in 3.5% NaCl solution. In the presence of L-proline a surface
morphology consisting of fine and homogeneous tightly-packed non-porous grains
covering the entire cathode surface was obtained as detected by SEM.
structure of electrodeposited nickel. In this work, considerable improvements have
been found by using L-proline as a complexing agent in a Watts-type nickel bath.
This study determined the influence of L-proline concentrations on the cathodic
efficiency, cathodic polarization, anodic linear stripping voltammetry, current-time
transients, macrothrowing power and Wagner number. The presence of L-proline
leads to a great shift in the polarization curve and the deposition potential towards
more noble potentials, indicating the catalytic effect of L-proline on the reduction of
Ni(II) ions. The kinetic data confirmed that the exchange current density is greatly
enhanced with increasing L-proline concentration. The Tafel slopes in the presence of
L-proline are higher (141–160 mV decade−1) than that without L-proline (130.7 mV
decade−1). The constant values of αc, proposes that the Ni electrodeposition
mechanism is not influenced by the presence of L-proline. The corrosion property of
nickel coatings prepared from Watts-type nickel bath in the absence and presence of
L- proline was tested in 3.5% NaCl solution. In the presence of L-proline a surface
morphology consisting of fine and homogeneous tightly-packed non-porous grains
covering the entire cathode surface was obtained as detected by SEM.
Other data
Title | Catalytic effect of l-proline on the reduction of Ni(II) ions during nickel electrodeposition from a Watts-type nickel bath | Authors | N.F. El Boraei ; Ibrahim, Magdy | Keywords | L-proline; Electrodeposition; Polarization; Tafel lines; Chronoamperometry; Cathodic efficiency. | Issue Date | Aug-2018 | Publisher | Elsiever | Journal | Surface & Coatings Technology |
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