Cobalt single atom site isolated Pt nanoparticles for efficient ORR and HER in acid media

Hitherto, developing an economical and stable high-activity bifunctional Pt catalyst for oxygen reduction re-action (ORR) and hydrogen evolution reaction (HER) becomes necessary for fuel cells and regeneration fuel cell system. However, how to uniformly disperse and firmly fix Pt nanoparticles (NPs) on carbon support with optimal particle size for catalysis is still a big challenge. Herein, by taking advantage of the isolating effect of the cobalt (Co) single atom site to Pt, strong interaction between Co single atoms and Pt, and the confinement of the porous carbon matrix derived metal organic frameworks, we successfully evenly immobilize Pt NPs on ZnCo-ZIF originated porous nitrogen-doped carbon matrix with rich cobalt single atoms (Co SAs-ZIF-NC) as multiple active sites. Compared with the commercial Pt/C catalyst, Pt@Co SAs-ZIF-NC, with ultralow Pt loading and ideal particle size, not only increases the active center, but also promotes the catalysis kinetics, greatly improving the ORR and HER catalytic activity. Under acidic conditions, its half-wave potential (0.917 V) is superior to com-mercial Pt/C (0.868 V), and the mass activity (0.48 A per mgPt) at 0.9 V is 3 times that of Pt/C (0.16 A per mgPt), surpassing the U.S. DOE target of 0.44 A per mgPt. Besides, it also shows outstanding HER performance. At 20 and 30 mV, its mass activity is even 4.5 and 13.6 times that of Pt/C. When further employed for HER in seawater, its mass activity is about 4 times as high as that of Pt/C, demonstrating the great potential applications.

Automated summary

By utilizing the isolating effect of cobalt single atoms on platinum, strong interaction between cobalt single atoms and platinum, and the confinement of the metal organic framework-derived porous carbon matrix, platinum nanoparticles were successfully evenly immobilized on a nitrogen-doped carbon matrix with rich cobalt single atoms as multiple active sites. This not only increased the active centers, but also promoted catalysis kinetics, significantly improving catalytic activity for oxygen reduction and hydrogen evolution reactions.