Saadi, Fadl H. and Carim, Azhar I. and Verlage, Erik and Hemminger, John C. and Lewis, Nathan S. and Soriaga, Manuel P. (2014) CoP as an Acid-Stable Active Electrocatalyst for the Hydrogen-Evolution Reaction: Electrochemical Synthesis, Interfacial Characterization and Performance Evaluation. Journal of Physical Chemistry C, 118 (50). pp. 29294-29300. ISSN 1932-7447. doi:10.1021/jp5054452. https://resolver.caltech.edu/CaltechAUTHORS:20141020-091512216
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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 Co^(2+) and H_2PO_2^– 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·Co_2O_3) 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: η_(Pt) < η_(CoP film) = η_(CoP NP), η_(Ni_2P) < η_(CoSe)_2 < η_(MoS)_2 < η_(MoSe)_2.
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Additional Information: | © 2014 American Chemical Society. Received: June 2, 2014. Revised: September 27, 2014. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. A.I.C. acknowledges a National Science Foundation Graduate Research Fellowship for support. | ||||||||||
Group: | JCAP | ||||||||||
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Issue or Number: | 50 | ||||||||||
DOI: | 10.1021/jp5054452 | ||||||||||
Record Number: | CaltechAUTHORS:20141020-091512216 | ||||||||||
Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20141020-091512216 | ||||||||||
Official Citation: | CoP as an Acid-Stable Active Electrocatalyst for the Hydrogen-Evolution Reaction: Electrochemical Synthesis, Interfacial Characterization and Performance Evaluation Fadl H. Saadi, Azhar I. Carim, Erik Verlage, John C. Hemminger, Nathan S. Lewis, and Manuel P. Soriaga The Journal of Physical Chemistry C 2014 118 (50), 29294-29300 DOI: 10.1021/jp5054452 | ||||||||||
Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||
ID Code: | 50531 | ||||||||||
Collection: | CaltechAUTHORS | ||||||||||
Deposited By: | Ruth Sustaita | ||||||||||
Deposited On: | 20 Oct 2014 18:40 | ||||||||||
Last Modified: | 10 Nov 2021 18:57 |
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