Currently, oxygen reduction reaction (ORR) suffers from sluggish kinetics and high overpotential, which usually requires costly platinum (Pt)-based materials. Transition metal single-atom catalysts (M–N–C), such as Fe–N4 and Co–N4 with high ORR activity have been explored and considered to be the most promising catalysts for replacing precious metals. However, the low active site density and the thick catalyst layer in the electrode greatly hindered the mass transfer of the electrode. Various methods have been adopted to solve this problem—for example, using hierarchical porous structure and ultra-thin carbon spheres as carriers.
Click here for original story, Hierarchically porous carbon networks embedded with single iron sites for efficient oxygen reduction
Source: Phys.org