A ruthenium-based plasmonic hybrid photocatalyst for aqueous carbon dioxide conversion with a high reaction rate and selectivity

Photocatalytic CO 2 conversion has been paid great attention in an effort to produce renewable hydrocarbon fuels in a sustainable manner using solar energy. However, new catalytic materials still need to be developed to improve the conversion efficiency, selectivity, and stability for practical applications. Here we report a ruthenium-based asymmetric catalyst immobilized onto a plasmonic Au/TiO 2 heterostructure to efficiently and selectively convert CO 2 into formic acid in an aqueous solution. The plasmonic heterostructure promotes multi-electron transfer towards the catalyst through efficient charge separation at a Schottky junction. The ruthenium complex is stably immobilized onto the heterostructure by two phosphonate groups, and the catalytic centre is stabilized by bidentate π-backbonding. The photocatalytic structure exhibits a high turnover frequency of 1200 h −1 at 360 mW cm −2 , a superior selectivity towards formic acid (∼95%) even at a low pH (∼pH 3), and a remarkable reusability over 50 hours without loss of the catalytic activity. A cis -ruthenium complex fixed on a plasmonic Au/TiO 2 nanostructure efficiently converts CO 2 into formic acid even in low pH water.