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

Abstract

To mimic photosynthesis in green plants, it is a crucial challenge to drive water oxidation and CO 2 reduction in one single system. In this study, we present a bioinspired trinuclear pyridinedicarboxylate cobalt complex (Et 3 NH) 2 [Co III 2 Co II (OH 2 )(pda) 5 ]ÁH 2 O (1) that is capable of homogeneously electrocatalytic water oxidation and CO 2 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 oxygenevolving 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 À1 , respectively. Meanwhile, it also displays electrocatalytic activity for the reduction of CO 2 to CO with the TOF of 0.93 s À1 . The cobalt complex has good catalytic performance for the conversion of H 2 O and CO 2 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.

Two Novel Schiff Base Manganese Complexes as Bifunctional Electrocatalysts for CO2 Reduction and Water Oxidation

“…Complexes 1 and 2 are the first two compounds coordinated with Schiff base ligand for both water oxidation and CO 2 reduction. The complexes 1 and 2 show the electrocatalytic activity for water oxidation with TOFs of 3.66 s −1 and 7.88 s −1 with the overpotentials of 728 mV and 216 mV, meanwhile the catalytic reduction of CO 2 to CO with the TOF values of 0.38 s −1 at −1.65 V and 15.97 s −1 at −1.60 V, respectively, which are higher than or comparable with those of reported complexes ( Table S2 ) [ 31 , 32 , 33 , 34 ]. Through great efforts, we used the same Schiff base ligand L to obtain mononuclear Mn III complex 1 and hetero-binuclear Mn II –Cu II complex 2 for accurately comparing their catalytic behaviors.…”

“…In 2021, Wang’s group developed a mononuclear copper complex [Cu II L 1 2 ](ClO 4 ) 2 ·2CH 3 OH ( L 1 = methoxy-di-pyridin-2-ylmethanol) as a bifunctional electrochemical catalyst for CO 2 reduction and water oxidation, of which the turnover frequencies (TOFs) were 2.99 s −1 and 9.20 s −1 , respectively [ 33 ]. Later, they reported a multinuclear cobalt complex (Et 3 NH) 2 [Co III 2 Co II (OH 2 )(pda) 5 ] (H 2 pda = 2,6-pyridinedicarboxylic acid) as an excellent homogeneous electrochemical catalyst for water oxidation and CO 2 reduction, where the labile aqua ligand played an important role in improving the catalytic performance [ 34 ]. Except for the above works, most of the coordination complexes and other materials in this area are heterogeneous catalysts [ 35 , 36 , 37 , 38 , 39 ].…”

Homogeneous electrochemical water oxidation catalyzed by cobalt complexes with an amine–pyridine ligand

“…S21 †), affording faradaic efficiencies of 96% and 97%, respectively, which are comparable with those of previously reported homogeneous cobalt-based WOCs. [37][38][39][40] The difference in the amount of oxygen production indicates that the catalytic activity of complex 2 is much lower than that of complex 1.…”

Electrochemical water oxidation catalyzed by a mononuclear cobalt complex of a pentadentate ligand: the critical effect of the borate anion

“…[31][32][33][34][35][36][37] Nonetheless, they are less used for homogeneous electrochemical water oxidation. [38][39][40][41] It was reported that nanoparticles of cobalt oxides or cobalt hydroxides generated during the synthesis of cobalt complexes are also catalytically active for water oxidation, causing confusion regarding the interpretation of the intrinsic properties of the as-synthesized cobalt complexes. 42,43 In this work, we report the synthesis, electrochemical characterization, and electrocatalytic properties of a mononuclear cobalt complex [Co(N3Py2)(H 2 O)](ClO 4 ) 2 (1) of high purity (N3Py2 = 2,5,8-trimethyl-1,9-bis(2-pyridyl)-2,5,8-triazanonane) (Fig.…”

“…31–37 Nonetheless, they are less used for homogeneous electrochemical water oxidation. 38–41 It was reported that nanoparticles of cobalt oxides or cobalt hydroxides generated during the synthesis of cobalt complexes are also catalytically active for water oxidation, causing confusion regarding the interpretation of the intrinsic properties of the as-synthesized cobalt complexes. 42,43…”