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Download fileAtomically Embedded Ag via Electrodiffusion Boosts Oxygen Evolution of CoOOH Nanosheet Arrays
journal contribution
posted on 2019-12-13, 16:37 authored by Changsoo Lee, Kihyun Shin, Chanwon Jung, Pyuck-Pa Choi, Graeme Henkelman, Hyuck Mo LeeLayered cobalt (oxy)hydroxides have received much attention
as
cost-effective and efficient catalysts for the oxygen evolution reaction
(OER) for electrochemical water splitting. Doping with guest cations
possessing different oxidation states such as Ag can change the chemistry
of conventional transition metal oxides and hydroxides, generating
unexpected electrocatalytic performances. However, Ag dopants have
been found to easily segregate at the surface of electrocatalysts,
which induces deactivation. Here, we fabricated Ag-doped CoOOH nanosheet
arrays using electrochemical deposition, followed by a simple electrochemical
diffusion approach. Surprisingly, we revealed, through atom probe
tomography (APT), secondary
ion mass spectroscopy (SIMS), and energy-dispersive spectroscopy (EDS)
that Ag atoms are homogeneously distributed without any detectable
segregation. The Ag-doped CoOOH exhibits enhanced OER performance
in terms of overpotential, both experimentally (256 mV) and theoretically
(60 mV). The homogeneously distributed Ag dopants facilitate the phase
transformation from Co(OH)2 to the active phase of CoOOH.
Calculations show that Ag doping enhances phase stability of CoOOH
and exposed Ag dopants act as active sites by releasing −OH
adsorbates.
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Keywords
ion mass spectroscopyatom probe tomographyAPTtransition metal oxidesElectrodiffusion Boosts Oxygen Evolutionelectrochemical diffusion approachCoOOH Nanosheet Arrays Layered cobaltoxygen evolution reactionelectrochemical water splittingOEREDSAg-doped CoOOH exhibitsAg dopantsSIMSphaseAg dopants actAg-doped CoOOH nanosheet arrays