Acid-base equilibria of axial ligand and peripheral pyridyl group with stepwise formation of nine species of aluminum (III) tera(4-pyridyl) porphyrin

A Molecular Z-Scheme Artificial Photosynthetic System Under the Bias-Free Condition for CO2 Reduction Coupled with Two-electron Water Oxidation: Photocatalytic Production of CO/HCOOH and H2 O2

Bio-inspired molecular-engineered systems have been extensively investigated for the half-reactions of H2 O oxidation or CO2 reduction with sacrificial electron donors/acceptors. However, there has yet to be reported a device for dye-sensitized molecular photoanodes coupled with molecular photocathodes in an aqueous solution without the use of sacrificial reagents. Herein, we will report the integration of SnIV - or AlIII -tetrapyridylporphyrin (SnTPyP or AlTPyP) decorated tin oxide particles (SnTPyP/SnO2 or AlTPyP/SnO2 ) photoanode with the dye-sensitized molecular photocathode on nickel oxide particles containing [Ru(diimine)3 ]2+ as the light-harvesting unit and [Ru(diimine)(CO)2 Cl2 ] as the catalyst unit covalently connected and fixed within poly-pyrrole layer (RuCAT-RuC2 -PolyPyr-PRu/NiO). The simultaneous irradiation of the two photoelectrodes with visible light resulted in H2 O2 on the anode and CO, HCOOH, and H2 on the cathode with high Faradaic efficiencies in purely aqueous conditions without any applied bias is the first example of artificial photosynthesis with only two-electron redox reactions.

Nanocomposites of Titanium Dioxide and Peripherally Substituted Phthalocyanines for the Photocatalytic Degradation of Sulfamethoxazole

Phthalocyanines (Pcs) are often used in photosensitization of titanium(IV) oxide, a commonly employed photocatalyst, as such an approach holds the promise of obtaining highly stable and efficient visible light-harvesting materials. Herein, we report on the preparation, characterization and photoactivity of a series of composites based on TiO₂ and peripherally modified metallophthalocyanines: either tetrasulfonated or 4,4',4'',4'''-tetraazaphthalocyanines, with either copper(II), nickel(II) or zinc(II) as the central metal ion. Physicochemical characterization was performed using UV-Vis diffuse reflectance spectroscopy, hydrodynamic particle-size analysis, surface-area analysis using N₂ adsorption-desorption measurements and thermogravimetry combined with differential scanning calorimetry. The band-gap energy values were lower for the composites with peripherally modified phthalocyanines than for the commercial TiO₂ P25 or the unsubstituted zinc(II) phthalocyanine-grafted TiO₂. TG-DSC results confirmed that the chemical deposition, used for the preparation of Pc/TiO₂ composites, is a simple and efficient method for TiO₂ surface modification, as all the Pc load was successfully grafted on TiO₂. The photocatalytic potential of the Pc/TiO₂ materials was assessed in the photocatalytic removal of sulfamethoxazole-a commonly used antibacterial drug of emerging ecological concern. To compare the activity of the materials in different conditions, photodegradation tests were conducted both in water and in an organic medium.