3D porous graphitic nanocarbon for enhancing the performance and durability of Pt catalysts: a balance between graphitization and hierarchical porosity

• Published in: Energy & environmental science 2019-01, Vol.12 (9), p.283-2841
• Main Authors: Qiao, Zhi, Hwang, Sooyeon, Li, Xing, Wang, Chenyu, Samarakoon, Widitha, Karakalos, Stavros, Li, Dongguo, Chen, Mengjie, He, Yanghua, Wang, Maoyu, Liu, Zhenyu, Wang, Guofeng, Zhou, Hua, Feng, Zhenxing, Su, Dong, Spendelow, Jacob S, Wu, Gang
• Format: Article
• Language: English
• Subjects: Absorption spectroscopy; Aqueous electrolytes; Carbon; Catalysis; Catalysts; Corrosion; Corrosion resistance; Density functional theory; Dispersion; Doping; Durability; Electrolytic cells; Electron microscopy; Energy policy; ENERGY STORAGE; Federal agencies; Fuel cells; Fuel technology; Graphitization; High temperature; Hydrogels; Metals; Morphology; Multilayers; Nanoparticles; Nitrogen; Performance enhancement; Polymers; Porosity; Proton exchange membrane fuel cells; Pyrolysis; Stability; X ray absorption; X-ray absorption spectroscopy
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/c9ee01899a

Carbon supports used in oxygen-reduction cathode catalysts for proton exchange membrane fuel cells (PEMFCs) are vulnerable to corrosion under harsh operating conditions, leading to poor performance durability. To address this issue, we have developed highly stable porous graphitic carbon (PGC) produced through pyrolysis of a 3D polymer hydrogel in combination with Mn. The resulting PGC features multilayer carbon sheets assembled in porous and flower-like morphologies. In situ high-temperature electron microscopy was employed to dynamically monitor the carbonization process up to 1100 C, suggesting that the 3D polymer hydrogel provides high porosity at multiple scales, and that Mn catalyzes the graphitization process more effectively than other metals. Compared to conventional carbon supports such as Vulcan, Ketjenblack, and graphitized carbon, PGC provides an improved balance between high graphitization and hierarchical porosity, which is favorable for uniform Pt nanoparticle dispersion and enhanced corrosion resistance. As a result, Pt supported on PGC exhibits remarkably enhanced stability. In addition to thorough testing in aqueous electrolytes, we also conducted fuel cell testing using durability protocols recommended by the U.S. Department of Energy (DOE). After 5000 voltage cycles from 1.0 to 1.5 V, the Pt/PGC catalyst only lost 9 mV at a current density of 1.5 A cm 2 , dramatically exceeding the DOE support durability target (