Photocatalytic Oxidation of Hydrocarbons in Water by Ruthenium Complexes

Abstract

Reactions in the sun: A simple homogeneous photocatalytic system for the oxidation of organic substrates that consists of RuII‐H2O complex as catalyst, [Ru(bpy)3]2+ as photosensitizer, and [Co(NH3)5Cl]2+ as electron acceptor, can efficiently and selectively catalyze the oxidation of alkene and alcohols in water by using sunlight as the driving force (see scheme).

Hydrogen Production Coupled to Hydrocarbon Oxygenation from Photocatalytic Water Splitting

“…Using water as oxygen source, we and others have reported photocatalytic oxidation of organic substrates in homogeneous systems containing metal catalysts such as Ru and Mn for hydrocarbon oxidation, [Ru(bpy) 3 ] 2+ as photosensitizer (Ru PS; see Figure S1 in the Supporting Information), and [Co(NH 3 ) 5 Cl] 2+ as electron acceptor 6b,d. For example, an olefin can be oxidized to an epoxide with water as oxygen source, releasing two protons and two electrons [Eq.…”

“…(1)]. As shown in Scheme , the electrons derived from water were eventually transferred to [Co(NH 3 ) 5 Cl] 2+ in the photocatalytic system where [Ru(TPA)(H 2 O) 2 ] 2+ ( 1 ) catalyzes the hydrocarbon oxidation 6b. However, in artificial photosystems designed for H 2 production, protons should be the final electron acceptors [Eq.…”

“…Photo‐induced oxidation of hydrocarbons has been achieved using Ru PS, and we tested the applicability of Ir PS for hydrocarbon oxidation 6b. When styrene was used as a substrate, a turnover number (TON) of 28 was determined for the oxidation of styrene to benzaldehyde in a system containing 1 (1 μ M ), Ru PS (10 μ M ), and [Co(NH 3 ) 5 Cl] 2+ (500 μ M ) after exposure to LED light (450 nm; LED=light‐emitting diode) for 20 h. However, when Ir PS was used instead of Ru PS, we observed much less oxidation of styrene to benzaldehyde, with a TON of 7.…”

H2 generation and sulfide to sulfoxide oxidation with H2O and sunlight with a model photoelectrosynthesis cell

“…Moreover, using sunlight and water avoids the use of expensive and not very environmentally friendly oxidants such as CrO 3 or MnO 4 − . Furthermore, it generates molecular hydrogen that is a green carbon-free fuel vector [16]. One approach of achieving this overall reaction is via a photoelectrochemical cell (PEC) as shown in Fig.…”

Light driven styrene epoxidation and hydrogen generation using H2O as an oxygen source in a photoelectrosynthesis cell

“…This strategy also benefits from the formation of hydrogen as a byproduct that is also a clean energy vector. 12,13 Given the fact that the worldwide production of ethylene oxide represents 20 million tons per year, 14 and assuming that the reaction is driven by sunlight and with a 100 % atom economy, it would represent around 0.9 million tons of hydrogen produced in that process, or 2500 tons of hydrogen per day. In terms of energy, this represents the production of an impressive 2700 MWh per day just for this reaction.…”