Reduction of CO 2 Using Photocatalysts and a Photoelectrochemical Cell Consisted of Metal Complexes and Semiconductors

Abstract

Reduction of CO 2 producing high-energy compounds using water as an electron donor and sun light as an energy source has been investigating as useful technology for solving both depletion of the fossil resources and the global warming problem. Our group has successfully developed several types of hybrid photocatalysts consisting of semiconductors and metal complexes, which have both efficient CO 2 reduction ability supplied by the metal-complex unit and strong oxidation power of semiconductors. In this paper, our recent progresses of the visible-light-driven hybrid photocatalytic and photoelectrochemical systems for CO 2 reduction are introduced : (1) hybrids consisting C 3 N 4 and Ru(II) mononuclear complexes, (2) semiconductors, e.g., TaON, and a Ru (II) -Ru ʼ (II) binuclear complex, (3) a photoelectrochemical cell comprising a photocathode of the Ru(II)-Re(I) binuclear complex immobilized on p-type semiconductor NiO and a CoO x / TaON photoanode. First two systems can photocatalyze CO 2 reduction using methanol as an electron donor, and the third photoelectrochemical system can reduce CO 2 using water as a reductant.