Shape inducer-free polygonal angle platinum nanoparticles in graphene oxide as oxygen reduction catalyst derived from gamma irradiation

In this report, polygonal angle platinum nanoparticles (PtNPs) anchored on nitrogen doping reduced graphene oxide (NrGO) as oxygen reduction reaction (ORR) catalyst was synthesized by gamma irradiation assisted with in situ hydrolysis of urea without using any shape inducer, seed, or template. Urea was not only employed as the nitrogen source, but also offered more reductive radicals in the gamma system. The uniform dispersion and homogeneous size distribution of PtNPs are obtained on reduced graphene oxide (rGO), which is attributed to the synergy of restriction effects of GO and crush capacity of high energy gamma rays. In addition, the method simultaneously offers PtNPs with polygonal angle structure and doping nitrogen in rGO, thus provides more surface and corner defects on PtNPs and heteroatomic defects on rGO, which synergistically improve the ORR performance of the samples. The obtained polygonal angle PtNPs modified NrGO exhibit fantabulous ORR activity in alkaline media with enhanced onset potential (906 mV), half-wave potential (783 mV) and superior limit current density (6.74 mA·cm^-2) compared to the commercial Pt/C and those PtNPs supported on rGO composites. The results indicate that gamma irradiation assisted with in situ hydrolysis of urea can be a promising candidate method for preparation of high performance Pt-based catalysts in practical application.