Earth abundant transition metal complexes as molecular water oxidation catalysts

Coherency of nature has always inspired human to develop, produce and innovate by imitating it. Photosynthesis is amongst the most efficient bio-chemical reaction nature exudes and thus produces high-end products important for the sustenance of life. Four electron oxidation of water to oxygen is one of the toughest reactions in natural system that is easily effectuated by Photosystem II (PS-II). The remarkable endothermic nature of this reaction has made the water oxidation bottleneck of artificial photosynthetic energy production. Excellent performance of noble metals e.g. Ruthenium is overshadowed by its expensive nature. A dire need of non noble metal, particularly a 3d metal catalyst is essential. With the variable oxidation states, 3d metals posses the potential to peruse this novel task. In this review we will sum up and analyze the development in the field of water oxidation catalysts made from the 3d transition metal complexes highlighting their catalytic rates and mechanism. As the theme of the research is based on the natural process, a discussion is also made on the catalytic centre of the natural process (photosynthesis).