Corresponding Author

Zuo-Zhong Liang(liangzuozhong@snnu.edu.cn);
Xue-Peng Zhang(zhangxp@snnu.edu.cn);
Rui Cao(ruicao@snnu.edu.cn)


Understanding factors that influence the catalyst activity for oxygen reduction reaction (ORR) is essential for the rational design of efficient ORR catalysts. Regulating catalyst electronic structure is commonly used to fine-tune electrocatalytic ORR activity. However, modifying the hydrophilicity of catalysts has been rarely reported to improve ORR, which happens at the liquid/gas/solid interface. Herein, we report on two Co porphyrins, namely, NO2-CoP (Co complex of 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin) and 5F-CoP (Co complex of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin), and their electrocatalytic ORR features. By simultaneously controlling the electronic structure and hydrophilic property of the meso-substituents, the NO2-CoP showed higher electrocatalytic activity than the 5F-CoP by shifting the ORR half-wave potential to the anodic direction by 60 mV. Compared with the 5F-CoP, the complex NO2-CoP was more hydrophilic. Theoretical calculations suggest that NO2-CoP is also more efficient than 5F-CoP to bind with an O2 molecule to form CoIII-O2·-. This work provides a simple but an effective strategy to improve ORR activity of Co porphyrins by using electron-withdrawing and hydrophilic substituents. This strategy will be also valuable for the design of other ORR molecular electrocatalysts.

Graphical Abstract


molecular electrocatalysis, oxygen reduction, Co porphyrin, hydrophilicity, electronic structure

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