Carbon-Nano Fibers Yield Improvement with Iodinated Electrospun PVA/Silver Nanoparticle as Precursor via One-Step Synthesis at Low Temperature

Abstract

High temperature is required in carbon fiber synthesis in the carbonization step. However, direct high-temperature heating without the presence of additive materials would affect the yield and structure of carbon fibers produced. Thus, this study aims to synthesize carbon fibers from poly-vinyl alcohol (PVA), as the precursor and reducing agent, using silver nanoparticles (SNP) from silver nitrate (AgNO3) as additives. The pre-treatment of PVA was performed in three steps, i.e., mixing PVA/AgNO3, electrospinning, and iodination. The interaction of PVA and AgNO3 was assessed by FTIR, and SEM was used to characterize the electro-spun fibers prior and after iodination; Raman spectrophotometer was carried out to confirm the yield of carbon fibers. There was reduction in oxygen groups (3000–3800 cm−1) and emergence of -C=O (1100 cm−1) and -C=C- (1627 cm−1) functional groups, indicating formation of carbon layers. Based on the DT/GA results, the silver nanoparticles reduce the need of high temperature with optimum carbonization at 350°C and lead to the formation of more regular graphene layers. Graphene layers with a size distribution of 0.438 nm and well-organized structures were successfully formed, and the Raman shifting showed higher intensities of G and G’ bands in the presence of Ag. Based on DT/GA results, the yield of carbon fibers with iodinated PVA fibers and SNP as additive had higher rates around 800 µg/min, reaching 33% at 500°C. Thus, it is demonstrated that iodinated PVA/AgNO3 samples can significantly improve carbon fiber yield at low temperatures.

Poly (vinyl alcohol) based carbon nanofibers as freestanding anodes for lithium‐ion batteries

“…Although conventional CNF precursor PAN polymer needs oxidative stabilization, linear PVA chains must be stabilized via special suitable processes to suppress the thermal degradation. Stabilization of PVA under HCl, 21 H 2 SO 4 , 22 vapor or acidic impregnation with different salts, 23 very slow thermal dehydration, 15 and addition of catalyst and iodination 18,24,25 was reported in the literature. Compared to other methods, PVA stabilization under iodine vapor is a one-step facile stabilization approach at low temperatures, which provides a higher carbon yield.…”

“…18,25,27 Iodination process provides stable structure before high-temperature treatments via converting structure to polyene form, which is very crucial to obtain higher carbon yield during carbonization. 24,28 The iodination procedure was carried out through following previous studies. 18,24 Figure 1 shows iodination mechanism where polyene changes into a cyclic aromatic form with higher carbon yield after the heat treatment.…”

“…24,28 The iodination procedure was carried out through following previous studies. 18,24 Figure 1 shows iodination mechanism where polyene changes into a cyclic aromatic form with higher carbon yield after the heat treatment. 18,27 The final CNF properties are influenced by material and production parameters, such as carbonization temperature, heating rate, polymer concentration, and the type and amount of dopants in the precursor.…”

“…Water and iodine are separated from the reaction, and polyene structure is formed 18,25,27 . Iodination process provides stable structure before high‐temperature treatments via converting structure to polyene form, which is very crucial to obtain higher carbon yield during carbonization 24,28 . The iodination procedure was carried out through following previous studies 18,24 .…”

Multi-Functional Electrospun AgNO3/PVB and Its Ag NP/PVB Nanofiber Membrane

“…The size, distribution, and loading density of Ag NPs on other polymer nanofibers can be easily controlled by adjusting the AgNO 3 concentration, which significantly influences the antibacterial properties of composite nanofibers. Moreover, AgNO 3 and Ag NPs can serve as conductive materials for dynamic sensor applications and Raman spectroscopy substrates [ 27 ]. Nanosilver possesses many excellent properties, enabling multifunctionality within fibers.…”