Structure evolution mechanism of polyacrylonitrile films incorporated with graphene oxide during oxidative stabilization

Abstract

Oxidative stabilization is a key process for polyacrylonitrile (PAN)-based carbon materials. During this process, oxygen has a significant influence on the formation of cyclization structure and crosslinking structure of PAN matrix. Here, graphene oxide (GO) was used as filler in PAN matrix, the structure evolution of GO/PAN composite was studied during oxidative stabilization. Solubility measurement revealed that the crosslinking degree increased, while the cyclization degree of stabilized films decreased after GO incorporation. The effect of GO on the structure of PAN film was characterized by XRD, DSC, DMA, FTIR, and XPS. These results verified that GO could initiate the cyclization reaction of PAN at a lower temperature. The carboxylic groups on GO sheets might take part in the cyclization reactions during the heat treatment. Moreover, the oxygen-containing molecules released from GO decomposition during the heat treatment were beneficial to the formation of crosslinking structure. The possible mechanism of the structure evaluation was proposed in this article.

Gradient‐Distributed Nucleation Seeds on Conductive Host for a Dendrite‐Free and High‐Rate Lithium Metal Anode

“…The ZnO seeds are corroborated in the O 1s XPS of the ZnO-CNF samples by the ZnO bond at 530.4 eV (Figure 2c-e), [49,50] while the ZnO bond and Zn 2p peak do not appear in the CNF sample due to no ZnO source during preparation (Figure 2f and Figure S8, Supporting Information). The peaks at 288.1, 286.6, 285.5, and 284.7 eV in highresolution C 1s XPS are, respectively, attributed to CO, CO, CN, and CC ( Figure S10, Supporting Information), [51,52] while the peaks in N1s XPS ( Figure S11, Supporting Information) conform to pyridinic-N (398.3 eV), pyridone-N (399.7 eV), and quaternary-N (400.7 eV) in turn. [53] To evaluate the lithium nucleation ability induced by ZnO seeds, Li deposition onto Cu, CNF, ZnO(1%)-CNF, ZnO(3%)-CNF, and ZnO(5%)-CNF at 0.2 mA cm −2 was performed Small 2019, 15,1903520 ( Figure 2g-i).…”

Flexible Large-Area Graphene Films of 50–600 nm Thickness with High Carrier Mobility

“…In the pre-oxidation process (stage I), PAN undergoes cyclization reactions by free radicals. The electronegative functional groups on the GO surface, such as carboxyl, accelerate the cyclization reaction by nucleophilic attack on the nitrile group of the PAN chains [ 24 ]. Besides, oxygen-containing free radicals generated by the decomposition of GO during the cyclization process participate in the dehydrogenation and oxidation processes, further oxidizing the cyclized PAN chains and forming a carbonyl oxygen structure [ 24 , 25 ].…”

Atmospheric pressure plasma‐jet treatment of polyacrylonitrile‐nonwovens: Activation leading to high surface area carbon electrodes

“…Deconvolution of the highly resolved nitrogen (N1s) and carbon (C1s) signals allows identifying individual functional groups. [24][25][26][27] Plasma-jet treatment F I G U R E 1 Infrared-spectra of pristine polyacrylonitrile (PAN) (top), stabilized and plasma-jet treated stabilized PAN nonwoven (middle), and carbonized and plasma-jet treated carbonized PAN nonwoven (bottom). seems to give rise to amine (NH 2 ) groups on the surface for stabilized and carbonized nonwovens, indicating that the nitrogen process gas leads to oxidation on the fiber surface.…”

“…Deconvolution of the highly resolved nitrogen (N1s) and carbon (C1s) signals allows identifying individual functional groups. [ 24‐27 ] Plasma‐jet treatment seems to give rise to amine (NH 2 ) groups on the surface for stabilized and carbonized nonwovens, indicating that the nitrogen process gas leads to oxidation on the fiber surface. This observation is corroborated by an increase of nitrogen in the overall atomic composition (see Table 1).…”