Rational Synthesis of Polymeric Nitrogen N8-with Ultraviolet Irradiation and Its Oxygen Reduction Reaction Mechanism Study with in Situ Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy

Document Type

Article

Publication Date

11-5-2021

Abstract

Polynitrogen (PN) deposited on multiwalled carbon nanotubes was synthesized by cyclic voltammetry with ultraviolet (UV) irradiation. Compared to the sample formed without UV, a larger amount of N8-was synthesized and was found to distribute more uniformly on the MWNTs with 254 nm UV irradiation, indicating that the production of more azide (N3)0radicals as the precursors for synthesis of N8-by photoexcitation of azide (N3-) ions is a rate-limiting step for PN synthesis. An oxygen reduction reaction kinetics study indicated a four-electron reaction pathway on N8-, whereas a two-electron process occurs on N3-. Analysis by in situ shell-isolated nanoparticle-enhanced Raman spectroscopy revealed that the side-on and end-on O2adsorption occurred at N8-and N3-, respectively, confirming the electron transfer process. A full direct-methanol fuel cell study shows that methanol crossover typically reduces the current density of Pt/C by ∼40% but has very little effect on the performance of the PN-MWNT catalyst after testing for 120 h. Moreover, the power density from the PN-MWNT cathode is at least twice that from a Pt/C cathode.

Identifier

85118158384 (Scopus)

Publication Title

ACS Catalysis

External Full Text Location

https://doi.org/10.1021/acscatal.1c03102

e-ISSN

21555435

First Page

13034

Last Page

13040

Issue

21

Volume

11

Grant

CBET-1804949

Fund Ref

National Science Foundation

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