Photoinduced water splitting with oxotitanium tetraphenylporphyrin

Abstract

Photocatalytic splitting of water was investigated in a heterogeneous system consisting of micro-crystallites of oxotitanium tetraphenylporphyrin deposited on fused silica plates, immersed in water and excited within the visible range of their absorption spectra. The water photolysis was evidenced by the spectroscopic detection of hydroxyl radicals generated in the reaction. The experimental results confirm the mechanism of water splitting and generation of OH˙ radicals proposed theoretically by Sobolewski and Domcke [Phys. Chem. Chem. Phys., 2012, 14, 12807] for the oxotitaniumporphyrin-water complex. It is shown that photocatalytic water splitting occurs in pure water, and neither pH-bias nor external voltage is required to promote the reaction.

Laser-Induced Electron Transfer in the Dissociative Multiple Ionization of Argon Dimers

“…Photoinduced molecular charge-transfer (CT) across system boundaries is a key step in many important natural or technical processes such as solar-driven energy production [1,2], photocatalysis [3,4], or photosynthetic activity [5,6]. In these processes the relocation of charge, initiated by the absorption of a single photon by a molecule, is determined by the energetic and spatial structure of the system.…”

Titanyl Phthalocyanine as a Water Photooxidation Agent

“…In both cases, the reaction occurs without pH-bias (electrolyte is not required) and without external potential bias. The efficiency of hydroxyl generation is found to be higher for TiOPc than for TiOPP 16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 28 complexes. The larger energetic gap in TiOPc provides more excess energy and therefore a higher probability of the H-atom transfer reaction in the LMCT state.…”

“…Two identical gold electrodes were used to avoid any bias arising from difference in standard electrode potentials. Photo-response excitation spectra were recorded using one gold electrode (with deposited molecular layer) and a platinum wire The dosimetry of the OH• radicals was described previously 16 . Here we briefly summarize the method.…”

“…One 16 . In contrast to the hydroxyl radical generation, which can be produced only with excitation of the Soret band, the charge separation occurs for excitation of the Soret band as 24 well as of the Q band.…”

“…The earlier study of partial water photolysis with TiPPO revealed the existence of an ionic channel of water splitting 16 . The ionic channel in TiPPO was found to be much less efficient than the radical channel, but occurs even in pure water and without external voltage bias.…”