In recent years, renewable energy resources and global environmental problems have
become an increasingly vital and burning subject both in political and scientific sectors.
Rising standards of living in a growing world population will cause global energy
consumption to increase dramatically over the next half century. Energy consumption is
predicted to increase at least 2-fold, from our current burn rate of 12.8 TW to 28-35 TW
by 2050. If not, increases in energy intensity derived from economic and population
growth will be inextricably linked to increased carbon emissions. While the precise
response of the climate to continued runaway CO₂ emissions is not definitively known, it is abundantly clear that the current atmospheric CO₂ levels of 380 ppm are significantly higher than anything seen in the last 650 000 years¹. Smart and bold steps need to be taken in order to solve future energy crises and environmental issues. Fossil fuels are the principle source of energy for transportation. On the other hand, chief source of CO₂, a potential green house gas, emission in the atmosphere is the burning of fossil fuels in automobile combustion. Fuel cell powered transportation will most probably be the future to solve addressed problems but there is a big difficulty to generate cheap and pure clean fuels like hydrogen for these systems. Best possibility is to utilize solar energy for the production of hydrogen from water². At present, there is no efficient system available that makes use of solar energy effectively to produce hydrogen from water. Photosynthesis is an excellent model for an artificial solar energy conversion system to clean fuel, in which the oxidation of water is the most important primary step, providing electrons to the whole system to produce energy-rich reduction compounds. It consists ofa series of reactions starting with the splitting of water molecules into molecular oxygen, protons and electrons, followed by a chain of electron transfer reactions resulting in the production of NADPH and ATP – sources of chemical energy used in cell metabolism³. A four-electron process of water oxidation to give dioxygen is coupled with a oneelectron process of photoexcitation occurring at chlorophyll mediated by a Mn-complex. One approach to achieving four-electron water oxidation, and also to understanding the mechanism involved in the process, is to design a catalyst system in a condensed system smart matrix such as a polymer membrane. Getting inspiration from nature, there is a continuous effort to design an artificial photosynthetic system based upon harnessing the solar energy and capable of utilizing it efficiently for water splitting to generate oxygen and hydrogen. Oxygen evolving complex (OEC) is the heart of this photosynthetic system. Light-driven catalytic water oxidation occurs as the terminal step in photosystemII (PS-II) at the oxygen evolving complex (OEC) and is a potential half-reaction for artificial photosynthesis and photochemical energy conversion based on water splitting⁴. Efficient catalytic splitting of water using solar energy is a challenging and interesting topic of research with the potential to provide clean and renewable H₂ as an energy resource⁵. The major problem in this area of research is to establish an efficient and stable oxygen-evolving catalyst. There are many water splitting systems based on noble metal complexes and metal oxide catalysts but none of these systems have effective overall efficiency for water splitting⁶. Present report describes a system based on ruthenium catalyst for water splitting. An oxo-bridged trinuclear ammine ruthenium complex was immobilized onto polished graphite and gold surfaces. When potential applied externally, oxygen evolved as a result of water splitting by ruthenium catalyst. The amount of oxygen evolved is directly related to the quantity of current flowing through the system. The aim of this work is to design a model system where the involvement of metal centers, surrounding ligand and support materials leads to the formation of an active multielectron transfer site in a heterogeneous phase rather than in a homogeneous solution. The work will lead to the development of new era of modified systems based on new catalytic materials for water splitting.

References:
1- Lewis, N. S.; Nocera, D. G. Proc. Nat. Acad. Sci. U.S.A. 2006, 103, 15729.
2- Nocera, D. G. Dædulus 2006, 135, 112.
3- Tommos, C.; Babcock, G. T. Acc. Chem. Res. 1998, 31, 18.
4- Alstrum-Acevedo, J. H.; Brennaman, M. K.; Meyer, T. J. Inorg. Chem. 2005, 44, 6802.
5- Thummel, R. P.; Zong, R. J. Am. Chem. Soc. 2007, 127, 12802.
6- Esswein, A. J.; Nocera, D. G. Chem. Rev. 2007, 107, 4022.