(2) the co-catalysts can reduce the energy barrier of methane activation. The effect of attaching a gold nano cluster (Au6 -) on TiO2 cluster for adsorption of CH4 and formation to ethane was studied. The Au6 -was attached on TiO2 with two oxygen vacancy. The resulting Au6TiO2 nano cluster has one unpaired electron and a positive charge. There were three unique binding positions of gold nano cluster on TiO2 cluster (Figure ). Out of the three possibilities, structure 13, Fig. , where the gold nano cluster is adjacent to the binding site of CH4 on Ti atom was found to be stable one. The C-H activation energy barrier with Au6 -cluster on TiO2 was 155.6 kJ/mol and energy for the reaction 27.4 kJ/mol, indicates a forward reaction. The reaction energy with Au6 -coupled TiO2 catalyst is only ~ 2kJ/mol higher compared to bare TiO2 nano cluster as catalyst. This may be due to reorganization energy compensation of the strain between Au and TiO2 nano cluster interface in case of Au6TiO2 compared to bare TiO2 nano cluster. The CH3 carbon in transition state 14, Fig. has a high negative charge of -1.0084 (C17)… with carbanion nature. The resulting product 15, Fig. was higher in energy than the