Han, Yu; Yin, Shuhu; Chen, Youhu; Chen, Chi; Yan, Wei; Cheng, Xiaoyang; Li, Yanrong; Zhang, Tianen; Yang, Jian; Jiang, Yanxia; Sun, Shigang

JOURNAL OF ELECTROANALYTICAL CHEMISTRY

2022, 914, 1572-6657

Han, Yu; Yin, Shuhu; Chen, Youhu; Chen, Chi; Yan, Wei; Cheng, Xiaoyang; Li, Yanrong; Zhang, Tianen; Yang, Jian; Jiang, Yanxia; Sun, Shigang

The cost and efficiency issues of cathodic electrocatalyst for oxygen reduction reaction (ORR) hinder a broad application of fuel cells. Therefore, it is necessary to develop highly efficient and sustainable ORR electrocatalysts of platinum group metal-free (PGM-free). The atomically dispersed FeCoNC-10 electrocatalysts were constructed by incorporating Fe phthalocyanine (FePc) molecules into bimetallic metal-organic frameworks (BMOF) followed by one-step pyrolysis. It showed remarkable ORR activity in acidic medium compared with FeNC and CoNC catalysts. The Fe-Co bimetallic sites were confirmed in FeCo-N-C, together with abundant isolated FeN4 and CoN4 sites. Theoretical study revealed that the bimetallic site can enhance O2 adsorption and elongate O-O bond length rather than FeN4 and CoN4. This can result in facile cleavage of the O-O bond and thus a direct 4e- ORR process. FeCoNC-10 catalyst showed enhanced ORR stability, due to very weak Fenton-type reaction related to Co species. Membrane electrode assemblies (MEAs) consisted of the FeCoNC-10 was applied in the cathode. It showed a peak power density of 100 mW cm-2 in a direct methanol fuel cells (DMFCs) with superior methanol tolerance. This work sheds light on the mechanism of atomically dispersed Fe/Co dual-doped carbon in enhancing ORR activity and stability, which enables the cost-effective ORR electrocatalyst design to achieve robust fuel cell performance.