TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Electrode: The electrode is linked with a 2,2'-bipyridine ligand via a -SH, -COOH or -PO3H2 linker group, where linker groups are substituted at the 4,4'-positions of the 2,2'-bipyridine ligand. Preferred Method: In the method (M1), the required overpotential of the electrolysis process is provided by a source of sustainable energy selected from wind, solar, wave or tidal power energy.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (Claimed): Preparation of the compound (I) involves heating a mixture of (RuCl2(Ar'))2 dimer with a modified bipyridine ligand having COOH or PO3H2 groups on its 4,4'-positions in methanol, filtering the resulting chloro complexes, drying and converting into aqua (OH2) complexes by stirring with aqueous AgNO3 in methanol. The process involves contacting ligand BL as dissolved in an aqueous alkanol mixture with (M'X2(Ar'))2-dimer, oligomer or polymer as dissolved in alkanol at 25-40 degrees C, where the composition is obtained as a solid after filtration and drying. Preferred Complex: In the complex, the direct bridge connecting the two nitrogen atoms of the bidentate ligand BL contains two carbon atoms. The complex (I) excludes (Ru(4,4'-dicarboxy-2,2'-bipyridine)Cl(cymene))NO3 complex. Preferred Definitions:    M' = most preferably Ru or Ir;    Ar' = cyclopentadiene, pentamethylcyclopentadiene, benzene, mesitylene, para-cymene, durene, hexamethyl benzene, cyclooctadiene or cyclooctatetradiene;    A' = Cl-, Br-, ClO3-, ClO4-, CH3COO-, NO3-, PF6-, BF4-, (CO3)2- or (SO4)2-;    BL = 2,2'-bipyridine (optionally substituted).    SPECIFIC COMPOUNDS - A ((para-cymene)Ru(II)(4,4'-dicarboxylic acid-2,2'-bipyridine)-OH2)2+ (I'), is specifically claimed as the cataionic part of the compound (I).    EXAMPLE - Methanol (25 ml) was added to (methanol/water (MeOH/H2O)) (1 ml) dissolved solution of 4,4'-dicarboxylic acid-2,2'-bipyridine (H2dcabpy) (1 mmol) and sodium hydroxide (NaOH)/sodium methoxide (NaOMe) (2 mmol) and mixed well. The solution was poured into a stirred mixture of methanol (30 ml) and (RuCl2(para-cymene))2 dinner (0.5 mmol). The resultant mixture was further stirred for 2 hours at 25-35 degrees C. After filtration, the pH was lowered to 1-2 by addition of 0.5M HCl, to obtain ((para-cymene)Ru(II)(4,4'-dicarboxylic acid-2,2'-bipyridine)Cl)+. The ((para-cymene)Ru(II)(4,4'-dicarboxylic acid-2,2'-bipyridine)Cl)+ was converted into aqua (OH2) version i.e. ((para-cymene)Ru(II)(4,4'-dicarboxylic acid-2,2'-bipyridine)-OH2)2+ by stirring aqueous solution of silver nitrate (1.1 equivalent) in methanol (1:1, H2/MeOH) for 30 minutes.