Hydrogen from water, photochemical generation

Thus, equations (21) to (26) have been proposed for the photochemical generation of hydrogen from water employing [Ru(bipy)3]2+ as sensitizer and MV2+ as electron relay (R). The individual reactions are now considered in detail. 

Note 2 More efficient methods than electrolysis for obtaining hydrogen from water are under investigation. One of these is thermochemical decomposition. Another is photochemical decomposition by solar radiation, either directly or via a solar power generator. Photolytic decomposition of water with platinum catalyst has been achieved. Hydrogen can also be obtained by photolytic decomposition of hydrogen sulfide with cadmium sulfide catalyst. 

Chatterjee, S., Sarkar, S., Bhattacharyya, S.N. Size effect in the photochemical generation of hydrogen from water by colloidal Fe203 particles. J. Photochem. Photobiol. A 72,183 (1993)... 

Transition-metal catalyzed photochemical reactions for hydrogen generation from water have recently been investigated in detail. The reaction system is composed of three major components such as a photosensitizer (PS), a water reduction catalyst (WRC), and a sacrificial reagent (SR). Although noble-metal complexes as WRC have been used [214—230], examples for iron complexes are quite rare. It is well known that a hydride as well as a dihydrogen (or dihydride) complex plays important roles in this reaction. 

A challenge is to develop practical thermal or photochemical processes for generating hydrogen from its most abundant source—water." ... 

Tien HT, Chen JW (1989) Hydrogen generation from artificial sea water in a semiconductor septum electrochemical photovoltaic cell. Photochem Photobiol 49 527-530... 

The OH (X2n) can be generated from the photolysis of water, hydrogen peroxide, and nitric and nitrous acid. Reactions of OH(A2n) with various hydrocarbons arc important in understanding photochemical smog formation (see Section VIII—2). 

Hydrido species such as HCo[P(OPh)3]3(MeCN) catalyze the homogeneous hydrogenation of unsaturated substances. In the crystal HCo(CO)2(PPh3)2 can adopt both sp and tbp structures.35 The ion [Co(bipy)3]+ reduces water to H2 and C02 to CO the complex can be generated photochemically from [Co(bipy)3]"+ precursors.36... 

---