Catalysis of hydrogen evolution via deposition of palladium onto electrodes modified with an N,N'-dialkyl-4,4'-bipyridinium-based polymer: dependence of rate on palladium coverage

Journal Article · Thu Aug 30 04:00:00 EDT 1984 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150662a008· OSTI ID:5987232

Harrison, D J; Wrighton, M S

The H/sub 2/ evolution activity of indium tin oxide (ITO) (PQ/sup 2+/+/)/sub n//Pd surfaces has been characterized in pH 2.8/1 M KCl aqueous solution where (PQ/sup 2+/+/)/sub n/ is a redox polymer derived from an N,N'-dialkyl-4,4'-bipyridinium monomer and Pd is deposited onto the outer surface of the polymer by reduction of PdCl/sub 4//sup 2 -/. The coverage of (PQ/sup 2+/+)/sub n/ used, (4-5) x 10/sup -8/ mol/cm/sup 2/, can carry a maximum current density, i/sub E/, of 11-15 mA/cm/sup 2/. When the Pd coverage is approx. 5 x 10/sup -8/ mol/cm/sup 2/ the maximum current from kinetic limitations only, i/sub k/, for H/sub 2/ evolution is approx. 20 mA/cm/sup 2/. However, the observed current, i/sub obsd/, is limited by both I/sub E/ and i/sub k/. We predict that a polymer coverage of approx. 1 x 10/sup -8/ mol/cm/sup 2/ with a Pd coverage of 5 x 10/sup -8/ mol/cm/sup 2/ is sufficient to give an observed H/sub 2/ evolution current density of 15-20 mA/cm/sup 2/. These considerations apply at pH 2.8 and an electrode potential of -0.78 V vs. SCE. The Pd deposited onto the polymer is found to be significantly less active than Pd deposited directly onto ITO, but structured ITO/(PQ/sup 2+/+/)/sub n//Pd interfaces have been demonstrated to have good integrity and can provide significant current density, greater than or equal to 10 mA/cm/sup 2/, at modest, < 10/sup -7/ mol/cm/sup 2/, Pd coverages. 12 references, 3 figures, 1 table.

• Research Organization: Massachusetts Inst. of Tech., Cambridge
• OSTI ID: 5987232
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:18; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
080101* -- Hydrogen-- Production-- Electrolysis
ALKALI METAL COMPOUNDS
AMINES
AMMONIUM COMPOUNDS
AQUEOUS SOLUTIONS
AUGER ELECTRON SPECTROSCOPY
AZINES
CATALYSIS
CATALYTIC EFFECTS
CHLORIDES
CHLORINE COMPOUNDS
DATA
DISPERSIONS
ELECTRODES
ELECTRON SPECTROSCOPY
ELEMENTS
EXPERIMENTAL DATA
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
HYDROGEN
HYDROGEN PRODUCTION
INFORMATION
METALS
MIXTURES
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PALLADIUM
PH VALUE
PLATINUM METALS
POTASSIUM CHLORIDES
POTASSIUM COMPOUNDS
PYRIDINES
PYRIDINIUM COMPOUNDS
QUATERNARY COMPOUNDS
SOLUTIONS
SPECTROSCOPY
TRANSITION ELEMENTS
VOLTAMETRY