Wang Yu-Han, Tseng Yun-Jou, Kumbhar Sharad V, Chang Hao-Ting, Yang Tzuhsiung, Lu I-Chung, Wang Yu-Heng
Department of Chemistry, National Tsing Hua University, 101, Sec 2, Kuang-Fu Rd., Hsinchu, 30013, Taiwan.
Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., South Dist., Taichung, 402, Taiwan.
Chemistry. 2025 Feb 17;31(10):e202403583. doi: 10.1002/chem.202403583. Epub 2025 Jan 20.
This study focuses on enhancing the water oxidation reaction (WOR) efficacy of dinuclear cobalt complex catalysts from both kinetic (turnover frequency, TOF) and thermodynamic (overpotential, η) perspectives. For this purpose, we synthesized six dinuclear cobalt complexes 1-6 comprising non-innocent ligands with different electronically active substituents (-OMe (1), -Me (2), -H (3), -F (4), -Cl (5), and -CN (6)). The electronic effects on the electrochemical WOR under neutral, acidic, and alkaline conditions were investigated experimentally and computationally. X-ray crystallography revealed that the valence state of the cobalt complexes was affected by electronic effects, affording different catalytic potentials, as evidenced by electrochemical measurements. Kinetic and spectroscopic studies confirmed that the synergistic effect of catalyst identity and reaction media changes the reaction mechanism of each catalyst. The WOR performance of 1-6 was tunable through ligand electronics and solvent effects, with the log(TOF)-η analysis highlighting an operational η as low as 40 mV. This study provides valuable insights into optimizing WOR catalysis through molecular design and environmental tuning.
