Highly efficient photocatalytic reduction of CO2 and H2O to CO and H2 with a cobalt bipyridyl complex

Abstract

The development of efficient molecular catalysts for visible-light driven CO2 reduction, based on abundant materials, is necessary to meet energy demands and address environment problems. In this work, a Co(bpy)2Cl2 catalyst was developed and showed high efficiency and durability for the photocatalytic reduction of CO2 and protons. Yields of CO and H2 as high as 62.3 and 69.9 µmol were achieved and the turnover numbers (TONs) reached 6230 and 6990, respectively, under light irradiation (λ > 420 nm) for 4 h, indicating that the mixture gases could be a candidate as syngas. The apparent quantum yield was determined to be 2.1% for CO. Mechanistic studies revealed oxidative quenching of the photosensitizer Ru(bpy)3Cl2 by the catalyst. The photocatalytic performance, flexible synthesis and non-noble metal catalyst in our system show great promise for the practical application of Co(bpy)2Cl2 to photocatalytic reduction of CO2.