Electrochemically CO2 conversion using homogeneous and nanostructured heterogeneous Ru (II) electrocatalysts

The reduction of carbon dioxide to desirable products is an urgent goal in favour of the environment, the energy-cycle and mankind. We report the electrochemical reduction of CO2 to carbon monoxide by means of the ho-mogeneous electrocatalyst (1), Ru(bpy)2(L1)2, and the heterogeneous one (2), Ru(bpy)2L12@-SiO2-NH2@Fe3O4) (meaning 1 fixed onto functionalized nanoparticles). The catalysts have been synthesized and characterized using different spectroscopies (IR, UV-vis, EDAX, SEM and PXRD(. The crystal structure of 1, determined by X-ray diffraction, revealed a distorted octahedral coordination of the Ru (II) center. In 1 the electrocatalytic activity of the complex was investigated for the CO2 reduction under various reaction conditions; this complex is stable and active for the CO2 reduction to CO in 0.5 M of a TBHP acetonitrile electrolyte. Under heterogeneous condition, both 1 and 2 show small electrocatalytic activity for CO2 reduction and remarkable electrocatalytic activity for H2 evolution in 0.5 M KHCO3 aqueous electrolyte, which can be attributed to the HCO3? mediated hydrogen evolution reaction (HER) process. It is expected that this could introduce a new type of the electrocatalysts for syngas production from CO2 and H2O in both homogeneous and heterogeneous cat-alytic systems.