Micro-scale hollow nanosphere as highly efficient ORR electrocatalyst derived from the self-assembly of triblock copolymer (L64)

Abstract

The micro-scale hollow nanosphere with rich defect was synthesized by pyrolyzing the transparent film composed of the co-polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) triblock copolymer (L64) and Zn (OH)2, which formed in the mixture solution of ethanol and n-hexane. The content increase of n-hexane in the mixture solution would decrease the formation rate during self-assembly of block copolymers, which was beneficial for forming the uniformly distributed nano-carbon spheres obtained. As the ratio of ethanol and n-hexane is 1:1, the as-synthesized product (noted as C (1:1)) has an even pore size (7 nm) and hollow nanosphere morphology, which possessed the highest specific surface area (753 m2 g−1) and disorder (ID/IG, 3.4). In terms of ORR performance, C (1:1) exhibits not only superior cycle stability and methanol-tolerance than 20% Pt/C but also comparable half-wave potential (0.76 V vs. RHE) to that of commercial 20% Pt/C (0.80 V) in 0.1 M KOH solution.