Visible Light-Driven Selective Reduction of CO2 by Acetylene-Bridged Cobalt Porphyrin Conjugated Polymers

Photocatalytic conversion of CO2 into renewable fuels with high efficiency and selectivity is desirable for solar energy utilization, but remains a great challenge. Herein, cobalt(II)-porphyrin functionalized conjugated polymers with acetylene bridging units, assembled through the Sonogashira cross coupling reaction, as heterogeneous catalysts for CO2 photoreduction were presented. Experimental investigations and density functional theory calculations demonstrated the crucial roles of Co centers in porphyrin units for CO2 activation and conversion, while excessive acetylene group prompted the competing hydrogen evolution reaction and reduced the selectivity. Thus, the CoPor-DBBP afforded superior activity for the CO generation with a rate of 286.7 mu mol g(-1) h(-1) and high selectivity of up to 90.4 %. This work presents a new insight for rationally designing of porphyrin-based conjugated polymers as energetic photocatalyst in CO2 reduction.