Microstructural analysis of nitrogen-doped char by Raman spectroscopy: Raman shift analysis from first principles

Michael Ayiania (1) , Elsa Weiss-Hortala (2) , Matthew Smith (1, 3) , Jean-Sabin Mcewen (1, 3, 4) , Manuel Garcia-Perez (1, 5)

1 WSU - Washington State University
2 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement
3 Department of Physics and Astronomy [WSU Pullman]
4 PNNL - Pacific Northwest National Laboratory
5 Bioproducts Science and Engineering Laboratory

Nitrogen-doped materials are known to possess unique functional properties, making these materials potentially useful for environmental applications, heterogeneous catalysis, and electronics. In this paper we constructed first principles-based models of various polyaromatic structures containing N functionalities to better understand the effect of these functional groups on char Raman spectra. The presence of N functional groups induces active vibrations in the regions between 1400 and 1550 cm−1 and 1605-1650 cm−1. We used these insights to inform the deconvolution of N-doped cellulose char produced between 350 and 700 °C using cellulose/melamine blends 2:1. A consistent increase in the intensity of the D and G bands is observed with temperature, which is related to an increase in size of the aromatic cluster. A consistent decrease in the A (the valley region) band is related to the loss of heteroatoms (mainly N and O) as the carbonization temperature increases from 350 to 700 °C. Although the modeling results reported in this manuscript are used to inform the deconvolution of N-doped char Raman spectra, they are also relevant to study other nanocarbon-based materials.

Mots clés: Density functional theory calculations; N-doped carbons; Raman spectroscopy

Domaines: Sciences de l'ingénieur [physics]

Michael Ayiania, Elsa Weiss-Hortala, Matthew Smith, Jean-Sabin Mcewen, Manuel Garcia-Perez. Microstructural analysis of nitrogen-doped char by Raman spectroscopy: Raman shift analysis from first principles. Carbon, 2020, 167, pp.559-574. ⟨10.1016/j.carbon.2020.05.055⟩. ⟨hal-02638698⟩