Kinetics of reduction of dimethylferrocenium ion in acetonitrile at nearly ideal regions of n-tungsten diselenide electrodes

Journal Article · Thu Dec 15 04:00:00 EST 1994 · Analytical Chemistry (Washington); (United States)

DOI:https://doi.org/10.1021/ac00096a020· OSTI ID:6717979

Howard, J N; Koval, C A ^[1]

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1. Univ. of Colorado, Boulder, CO (United States)

An electrochemical minicell was used to investigate the interfacial properties and redox kinetics at nonilluminated regions (2-3 mm in diameter) of n-WSe[sub 2] crystals in acetonitrile solutions. Interfacial capacitance measurements at high and low frequencies together with the shape of current potential curves were used to identify regions of n-WSe[sub 2] crystals with properties that approached what is expected for an ideal semiconductor-solution interface. Kinetic currents measured for reduction of dimethylferrocenium ion at these nearly ideal regions were independent of concentration between 0.05 and 250 mM. Since the reduction potential of the dimethylferrocenium-dimethylferrocene couple is 0.65 V positive of the conduction band edge of n-WSe[sub 2], the rate constant for outer-sphere electron transfer between conduction band electrons and dimethylferrocenium ions should be near its maximum value. However, the capacitance- and kinetic current-potential data indicate that this rate constant at n-WSe[sub 2] must be less than 10[sup [minus]17] cm[sup 4] s[sup [minus]1]. The concentration independent currents can be explained by postulating the existence of a low level of surface states, N[sub ss] = 1 x 10[sup 12] cm[sup [minus]2], with energies several hundred millivolts positive of the conduction band. 40 refs., 7 figs., 1 tab.

• DOE Contract Number: FG02-84ER13247
• OSTI ID: 6717979
• Journal Information: Analytical Chemistry (Washington); (United States), Journal Name: Analytical Chemistry (Washington); (United States) Vol. 66:24; ISSN 0003-2700; ISSN ANCHAM
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400400 -- Electrochemistry
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ACETONITRILE
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
ELECTROCHEMISTRY
ELECTRODES
ELECTRON TRANSFER
IONS
IRON COMPLEXES
KINETICS
MATHEMATICAL MODELS
NITRILES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
REDUCTION
REFRACTORY METAL COMPOUNDS
SELENIDES
SELENIUM COMPOUNDS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
TUNGSTEN SELENIDES
VOLTAMETRY