Enhancing Electrochemical Efficiency of Hydroxyl Radical Formation on Diamond Electrodes by Functionalization with Hydrophobic Monolayers.

Electrochemical formation of high-energy species such as hydroxyl radicals in aqueous media is inefficient because oxidation of HO to form O is a more thermodynamically favorable reaction. Boron-doped diamond (BDD) is widely used as an electrode material for generating OH radicals because it has a very large kinetic overpotential for O production, thus increasing electrochemical efficiency for OH production. Yet, the underlying mechanisms of O and OH production at diamond electrodes are not well understood.

Proton-Induced Trap States, Injection and Recombination Dynamics in Water-Splitting Dye-Sensitized Photoelectrochemical Cells.

Water-splitting dye-sensitized photoelectrochemical cells (WS-DSPECs) utilize a sensitized metal oxide and a water oxidation catalyst in order to generate hydrogen and oxygen from water. Although the Faradaic efficiency of water splitting is close to unity, the recombination of photogenerated electrons with oxidized dye molecules causes the quantum efficiency of these devices to be low. It is therefore important to understand recombination mechanisms in order to develop strategies to minimize them.

Understanding the Effect of Monomeric Iridium(III/IV) Aquo Complexes on the Photoelectrochemistry of IrO(x)·nH2O-Catalyzed Water-Splitting Systems.

Soluble, monomeric Ir(III/IV) complexes strongly affect the photoelectrochemical performance of IrO(x)·nH2O-catalyzed photoanodes for the oxygen evolution reaction (OER). The synthesis of IrO(x)·nH2O colloids by alkaline hydrolysis of Ir(III) or Ir(IV) salts proceeds through monomeric intermediates that were characterized using electrochemical and spectroscopic methods and modeled in TDDFT calculations. In air-saturated solutions, the monomers exist in a mixture of Ir(III) and Ir(IV) oxidation states, where the most likely formulations at pH 13 are [Ir(OH)5(H2O)](2-) and [Ir(OH)6](2-), respectively.

Effects of electron trapping and protonation on the efficiency of water-splitting dye-sensitized solar cells.

Water-splitting dye-sensitized photoelectrochemical (WS-DSPECs) cells employ molecular sensitizers to absorb light and transport holes across the TiO2 surface to colloidal or molecular water oxidation catalysts. As hole diffusion occurs along the surface, electrons are transported through the mesoporous TiO2 film. In this paper we report the effects of electron trapping and protonation in the TiO2 film on the dynamics of electron and hole transport in WS-DSPECs.