Bioinspired cobalt molecular electrocatalyst for water oxidation coupled with carbon dioxide reduction

To mimic photosynthesis in green plants, it is a crucial challenge to drive water oxidation and CO2 reduction in one single system. In this study, we present a bioinspired trinuclear pyridinedicarboxylate cobalt complex (Et3NH)(2)[(Co2CoII)-Co-III(OH2)(pda)(5)]center dot H2O (1) that is capable of homogeneously electrocatalytic water oxidation and CO2 reduction simultaneously. The designed mix-valent cobalt complex is in a V-configuration composed of two terminal Co-III ions and one central Co-II ion coordinated with one water ligand, which is resemble to aqua ligation of the natural catalytic complex in oxygen-evolving complex (OEC). The electrochemical results show that this trinuclear cobalt complex could electrocatalyze water oxidation under neutral condition at the potentials of 1.15 V and 2.00 V versus NHE, with the Faraday efficiency as high as about 96% and 82%, and the TOF of 2.22 and 10.20 s(-1), respectively. Meanwhile, it also displays electrocatalytic activity for the reduction of CO2 to CO with the TOF of 0.93 s(-1). The cobalt complex has good catalytic performance for the conversion of H2O and CO2 into O-2 and CO, respectively, which may be mainly due to the key role of the flexible water ligand on the central Co-II ion in the catalytic process. This work represents the first multinuclear cobalt complex for mimicking bio-system to drive water oxidation coupled with carbon dioxide reduction simultaneously.