Voltammetric Measurement of Rates and Energetics for Surface Methoxylation of Si(100) in Methanol with Dissolved Electron Acceptors Using Si Ultramicroelectrodes.

The steady-state voltammetric responses of n-type Si(100) semiconductor ultramicroelectrodes (SUMEs) immersed in air- and water-free methanolic electrolytes have been measured. The response characteristics of these SUMEs in the absence of illumination were modeled and understood through a framework that describes the distribution of the applied potential across the semiconductor/electrolyte contact using four discrete regions: the semiconductor space charge, surface, Helmholtz, and diffuse layers. The latter region was described by the full Gouy-Chapman model.

Protection of GaInP Photocathodes by Direct Photoelectrodeposition of MoS Thin Films.

Catalytic MoS thin films have been directly photoelectrodeposited on GaInP photocathodes for stable photoelectrochemical hydrogen generation. Specifically, the MoS deposition conditions were controlled to obtain 8-10 nm films directly on p-GaInP substrates without ancillary protective layers. The films were nominally composed of MoS, with additional MoOS and MoO species detected and showed no long-range crystalline order.

Semiconductor Ultramicroelectrodes: Platforms for Studying Charge-Transfer Processes at Semiconductor/Liquid Interfaces.

Semiconductor ultramicroelectrodes (SUMEs) were prepared by photolithographic patterning of defined pinholes in dielectric coatings on semiconductor wafers. Methods are reported for interpreting their electrochemical response characteristics in the absence of illumination. Radial diffusion is reconciled with the diode equation to describe the full voltammetric response, allowing direct determination of heterogeneous charge-transfer rate constants and surface quality.

Concerted Electrodeposition and Alloying of Antimony on Indium Electrodes for Selective Formation of Crystalline Indium Antimonide.

The direct preparation of crystalline indium antimonide (InSb) by the electrodeposition of antimony (Sb) onto indium (In) working electrodes has been demonstrated. When Sb is electrodeposited from dilute aqueous electrolytes containing dissolved SbO, an alloying reaction is possible between Sb and In if any surface oxide films are first thoroughly removed from the electrode. The presented Raman spectra detail the interplay between the formation of crystalline InSb and the accumulation of Sb as either amorphous or crystalline aggregates on the electrode surface as a function of time, temperature, potential, and electrolyte composition.

Dynamic silver speciation as studied with fluorous-phase ion-selective electrodes: Effect of natural organic matter on the toxicity and speciation of silver.

The widespread application of silver in consumer products and the resulting contamination of natural environments with silver raise questions about the toxicity of Ag(+) in the ecosystem. Natural organic matter, NOM, which is abundant in water supplies, soil, and sediments, can form stable complexes with Ag(+), altering its bioavailability and toxicity. Herein, the extent and kinetics of Ag(+) binding to NOM, matrix effects on Ag(+) binding to NOM, and the effect of NOM on Ag(+) toxicity to Shewanella oneidensis MR-1 (assessed by the BacLight viability assay) were quantitatively studied with fluorous-phase Ag(+) ion-selective electrodes (ISEs).