Self-assembling electron-transport chains at electrodes modified with clay and related microporous solids

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:6980610

Rong, D

Clay-modified electrodes (CME) were made by binding Al[sub 13]O[sub 4](OH)[sub 28][sup 3+]-pillared montmorillonite to SnO[sub 2] surfaces via a 2-4 monolayer thick coating of polymerized silane. The cationic polymer provides binding sites for anions, while the relatively remote clay surface strongly absorbs cations. When the CME is exchanged with Fe(CN)[sub 6][sup 4[minus]] anions, and Os(bpy)[sub 3][sup 2+] is exchanged on the clay surface, and anions Fe(CN)[sub 6][sup 4[minus]] or Mo(CN[sub 8][sup 4[minus]]) are bound in the polymer film, photocathodic currents are generated with a quantum efficiency (per photon absorbed) of ca. 1%. Iron (III) tetrakis(4-sulfonatophenyl)porphyrin (FeTPPS[sup 3[minus]]) anions can be bound to the silane polymer, while electroactive cations such as Ru(NH[sub 3])[sub 6][sup 3+] and Os(bpy)[sub 2py]Cl[sup +] adhere to the clay surface. The axial ligation of the FeTPPS[sup 3[minus]] changes reversibly with solution pH. The FeTPPS[sup 3[minus]] contained within the silane film behaves as a pH-sensitive gate for electron transfer to and from the cations bound to the clay surface. Another strategy for preparing organized electroactive films on electrode surfaces involves the sequential adsorption of the components of the zirconium phosphate/phosphonate structure from aqueous solution. Pillared films thus synthesized can bind electroactive cations smaller than the pillar height (ca. 10 [angstrom]) and exclude larger cations. Spatially organized cation/anion electrode assemblies prepared in this way also act as current rectifiers. Molecular-level organization can be accomplished by self-assembly of two appropriate ions that differ in size onto/into zeolite Y surfaces. When zeolite Y is ion-exchanged with small redox-active ferrocene cations, and with large osmium tris(2,2[prime]-bypyridyl)ions, the two complexes form a molecular rectifier.

• Research Organization: Texas Univ., Austin, TX (United States)
• OSTI ID: 6980610
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400400* -- Electrochemistry
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMISTRY
CLAYS
COMPLEXES
ELECTROCHEMISTRY
ELECTRODES
ELECTRON TRANSFER
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IRON COMPLEXES
MATERIALS
MINERALS
MONTMORILLONITE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SILICON COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
POLYMERS
POROUS MATERIALS
PORPHYRINS
SILANES
SILICATE MINERALS
SILICON COMPOUNDS
SYNTHESIS
TIN COMPOUNDS
TIN OXIDES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
ZEOLITES
ZIRCONIUM COMPOUNDS
ZIRCONIUM PHOSPHATES