Abstract
Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co2+ and H2PO2 - on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO·Co2O3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (η) for the HER at a current density of 10 mA cm-2 and was stable under operation in highly acidic solution, with an increase in η of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: ηPt <ηCoP film = ηCoP NP, ηNi2P <ηCoSe2 <ηMoS2 <ηMoSe2.
| Original language | English |
|---|---|
| Pages (from-to) | 29294-29300 |
| Number of pages | 7 |
| Journal | Journal of Physical Chemistry C |
| Volume | 118 |
| Issue number | 50 |
| DOIs | |
| Publication status | Published - Dec 18 2014 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Energy(all)
Cite this
CoP as an acid-stable active electrocatalyst for the hydrogen-evolution reaction : Electrochemical synthesis, interfacial characterization and performance evaluation. / Saadi, Fadl H.; Carim, Azhar I.; Verlage, Erik; Hemminger, John C.; Lewis, Nathan S; Soriaga, Manuel P.
In: Journal of Physical Chemistry C, Vol. 118, No. 50, 18.12.2014, p. 29294-29300.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - CoP as an acid-stable active electrocatalyst for the hydrogen-evolution reaction
T2 - Electrochemical synthesis, interfacial characterization and performance evaluation
AU - Saadi, Fadl H.
AU - Carim, Azhar I.
AU - Verlage, Erik
AU - Hemminger, John C.
AU - Lewis, Nathan S
AU - Soriaga, Manuel P.
PY - 2014/12/18
Y1 - 2014/12/18
N2 - Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co2+ and H2PO2 - on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO·Co2O3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (η) for the HER at a current density of 10 mA cm-2 and was stable under operation in highly acidic solution, with an increase in η of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: ηPt <ηCoP film = ηCoP NP, ηNi2P <ηCoSe2 <ηMoS2 <ηMoSe2.
AB - Films of CoP have been electrochemically synthesized, characterized, and evaluated for performance as a catalyst for the hydrogen-evolution reaction (HER). The film was synthesized by cathodic deposition from a boric acid solution of Co2+ and H2PO2 - on copper substrates followed by operando remediation of exogenous contaminants. The films were characterized structurally and compositionally by scanning-electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectrophotometry. The catalytic activity was evaluated by cyclic voltammetry and chronopotentiometry. Surface characterization prior to electrocatalysis indicated that the film consisted of micrometer-sized spherical clusters located randomly and loosely on a slightly roughened surface. The composition of both the clusters and surface consisted of cobalt in the metallic, phosphide, and amorphous-oxide forms (CoO·Co2O3) and of phosphorus as phosphide and orthophosphate. The orthophosphate species, produced by air-oxidation, were eliminated upon HER electrocatalysis in sulfuric acid. The operando film purification yielded a functional electrocatalyst with a Co:P stoichiometric ratio of 1:1. After the HER, the surface was densely packed with micrometer-sized, mesa-like particles whose tops were flat and smooth. The CoP eletrodeposit exhibited an 85 mV overvoltage (η) for the HER at a current density of 10 mA cm-2 and was stable under operation in highly acidic solution, with an increase in η of 18 mV after 24 h of continuous operation. The comparative HER catalytic performance of CoP, film or nanoparticles, is as follows: ηPt <ηCoP film = ηCoP NP, ηNi2P <ηCoSe2 <ηMoS2 <ηMoSe2.
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U2 - 10.1021/jp5054452
DO - 10.1021/jp5054452
M3 - Article
VL - 118
SP - 29294
EP - 29300
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 50
ER -