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Underpotential Co-deposition of Au–Cu Alloys: Switching the Underpotentially Deposited Element by Selective Complexation
journal contribution
posted on 2014-03-11, 00:00 authored by Defu Liang, Giovanni ZangariUnderpotential
deposition and monolayer replacement processes are
widely used for the synthesis of core/shell catalysts and heterointerfaces.
Conventionally, only the more noble metal can be underpotentially
deposited on or replace the less noble metal, limiting the number
of accessible material configurations. We show here that the reverse
process is possible, using the Au–Cu pair as a model system.
By tuning the redox potentials of the two components via use of strong,
selective metal ion complexes, Au–Cu alloys could be synthesized
at will by (i) conventional underpotential co-deposition, whereby
Cu is reduced at underpotential in parallel with the overpotential
deposition of Au, or (ii) the reverse process, where Au is reduced
at underpotential, while Cu is deposited at overpotential. Selective
complexation also draws the redox potential of Au and Cu closer, resulting
in co-deposition under activation control for the noble metal and
precise alloy composition control by the applied potential, enabling
in principle the formation of arbitrary metal or alloy interfaces.
The alloys resulting from the two processes exhibit distinct enthalpy
of mixing, suggesting different degrees of short-range order and dissimilar
atomic configurations. These findings open new perspectives on underpotential
deposition phenomena and possibly new synthetic opportunities in electrodeposition.
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Keywords
alloy interfacesSelective complexationmonolayer replacement processesoverpotential depositionUnderpotentially Deposited ElementSelective ComplexationUnderpotential depositionunderpotential deposition phenomenaredox potentialsmetal ion complexesmodel systemprocesses exhibitalloy composition controlmaterial configurationsactivation controlCu
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