Polynitrogen (PN) species (Nn, n from 3 to 8) as highly energetic materials have attracted many theoretical calculations and predictions. Some researchers have experimentally observed N3, N4, N5 or their ions in the gas phase at high pressure and high temperature conditions. N8 and N8- were predicted to be stable at the room temperature by density functional theoretical (DFT) calculations. However, no molecular solid consisting of pure Nn species has been synthesized experimentally to date. In our work, a breakthrough synthesis of N8- polynitrogen anion stabilized on the positively charged sidewalls of multi-walled carbon nanotubes (MWNTs) was achieved for the first time using electrochemical cyclic voltammetry (CV) at ambient conditions. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopic data together with DFT calculations confirm the synthesis of a C2h symmetry chain structure of the N8 anion in (MWNT+N8-). Oxygen reduction reaction (ORR) experiments using MWNT+N8- as the cathodic catalyst unequivocally demonstrate, also for the first time, that N-N in a polynitrogen material is highly active for ORR with an even higher current density than that of a commercial Pt/Carbon (Pt/C) catalyst measured at the same conditions. This work will open the door to the synthesis of other polynitrogen materials and their potential use both as high energy and ORR catalytic materials.

N8- polynitrogen stabilized on multi-wall carbon nanotubes for oxygen reduction reactions at ambient conditions

2019 Spring National Meeting

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