Stabilized photoanodes for water oxidation by integration of organic dyes, water oxidation catalysts, and electron-transfer mediators

Abstract

Stabilized photoanodes for light-driven water oxidation have been prepared on nanoparticle core/shell electrodes with surface-stabilized donor-acceptor chromophores, a water oxidation catalyst, and an electron-transfer mediator. For the electrode, fluorine-doped tin oxide FTO|SnO/TiO|-Org1-|1.1 nm AlO|-RuP-WOC (water oxidation catalyst) with Org1 (1-cyano-2-(4-(diphenylamino)phenyl)vinyl)phosphonic acid), the mediator RuP ([Ru(4,4-(POH)-2,2-bipyridine)(2,2-bipyridine)]), and the WOC, Ru(bda)(py(CH)P(OH)) (bda is 2,2-bipyridine-6,6-dicarboxylate with x = 3 or 10), solar excitation resulted in photocurrents of ∼500 µA/cm and quantitative O evolution at pH 4.65. Related results were obtained for other Ru(II) polypyridyl mediators. For the organic dye PP (5-(4-(dihydroxyphosphoryl)phenyl)-10,15,20-Tris(mesityl)porphyrin), solar water oxidation occurred with a driving force near 0 V.

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation

“…1 (32,33). Preparation and characterization of nanoITO and SnO 2 /TiO 2 core/shell structures followed known literature procedures (34,35). In the current experiments, 4-μm-thick films of SnO 2 (composed of 15-nm nanoparticle) on FTO electrodes were coated with a 5-nm layer of TiO 2 to give the core/shell structures.…”

Artificial photosynthesis: opportunities and challenges of molecular catalysts

“…145 Because of the outstanding activity, Ru-bda-type WOCs have received extensive research attention worldwide and have been widely investigated by the Sun group among many other groups; researchers have studied the effect of axial ligands, [146][147][148][149] catalytic mechanisms, 80,81,[150][151][152][153][154][155][156] development of Ru-bda analogues [157][158][159][160] and applications of Ru-bda in AP devices. [161][162][163][164][165][166] The studies on the effect of axial ligands of Ru-bda-type WOCs were very fruitful. Electron-withdrawing and hydrophobic substituents on the axial ligands had positive influence on the water oxidation activity, e.g.…”

“…161,458,[480][481][482][483][484][485][486] A photocurrent density of approximately 1.0 mA cm À2 can be achieved for DSPEC cells with a Ru photosensitizer and Ru-bda type WOCs, with significantly improved stability. 165 5.1.2 DSPEC cells with molecular-catalyst-modified photocathodes. Considering the limitation of the light absorption range and driving force by only one chromophore, as well as the high reaction barrier of water splitting and CO 2 reduction, it is important to use photocathodes to finally fabricate tandem cells with a powerful driving force for overall water splitting or water oxidation-coupled CO 2 reduction.…”

Hybrid Photoelectrochemical Water Splitting Systems: From Interface Design to System Assembly

“…This allowed for rapid hole transfer from the organic dyes to the molecular catalyst for water oxidation. An impressive PEC stability was obtained for more than 3 h with ≈100% O 2 evolution obtained 141. Alternatively, an inorganic mediator has been used to obtain high stabilities by accelerating photogenerated charge transfer for PEC water splitting.…”