Photostability of Phosphonate-Derivatized, Ru^II Polypyridyl Complexes on Metal Oxide Surfaces

Abstract

The photostability of [Ru(II)(bpy)(2)(4,4'-(PO(3)H(2))(2)bpy)]Cl(2) (bpy = 4,4'-bipyridine) on nanocrystalline TiO(2) and ZrO(2) films was investigated using a standard measurement protocol. Stability was evaluated by monitoring visible light absorbance spectral changes, in real time, during 455 nm photolysis (30 nm fwhm, 475 mW/cm(2)) in a variety of conditions relevant to dye-sensitized solar cells and dye-sensitized photoelectrosynthesis cells. Desorption (k(des)) and photochemical (k(chem)) processes were observed and found to be dependent upon solvent, anion, semiconductor, and presence of oxygen. Both processes are affected by oxygen with k(des) and k(photo) noticeably smaller in argon saturated solution. Desorption was strongly solvent and pH dependent with desorption rates increasing in the order: methanol (MeOH) ≈ acetonitrile (MeCN) < propylene carbonate (PC) < pH 1 ≪ pH 7. Photochemistry occurred in MeOH and PC but not in aqueous, 0.1 M HClO(4) and MeCN. The anion and solvent dependence of k(photo) strongly suggests the photoreaction involves ligand substitution initiated by population of metal centered d-d states. The relative stability of -PO(3)H(2)- versus -COOH-substituted [Ru(II)(bpy)(3)](2+) was also quantitatively established.

Mono- and Dual-modified Titania with a Ruthenium(II) Complex and Silver Nanoparticles for Photocatalytic Degradation of Organic Compounds

“…Nevertheless, the impact of the adsorption-reaction conditions, such as pH value, solvent, temperature and the presence of oxygen, should also be taken into consideration (31). The rapid adsorption of ruthenium(II) on silver pre-modified titania was similar to our recent study for [Ru(bpy) 2 (4,4′-(CH 2 PO 3 H 2 ) 2 bpy)] 2+ adsorbed on gold pre-modified titania (24).…”

Selective Reduction of Aqueous Protons to Hydrogen with a Synthetic Cobaloxime Catalyst in the Presence of Atmospheric Oxygen

“…Figure 2 b ). These radicals were shown to result in a significant increase in the [RuP] 2+ desorption rate from the TiO 2 surface, [18] which could decrease the H 2 production activity in our heterogeneous system. In summary, we have described an inexpensive cobalt catalyst [CoP] À which evolves H 2 catalytically under highly desirable conditions: room temperature, pH-neutral water and atmospheric O 2 .…”

Perylene Diimide Aggregates on Sb-Doped SnO2: Charge Transfer Dynamics Relevant to Solar Fuel Generation

“…16 Furthermore, this approach generally involves less synthetic efforts, and it does not require the use of post-treatments based on advanced techniques (e.g., atomic layer deposition 17 ) or the deposition of polymeric overlayers 18 to further stabilize the linkage. On the other hand, the charge injection by these aggregates likely proceeds through π−π* exciton migration within the molecular assembly until achieving separation at the interface between the innermost molecular surface and the semiconductor.…”