ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Direct growth of long magnetic carbon nanotubes on Incoloy heating elements and its hydrophilic surface modification by atmospheric pressure plasma jets

Umam Hasan Setiawan, Teguh Endah Saraswati, Rinaldi Wahab Lubis, and I. F. Nurcahyo

Department of Chemistry, Faculty of Mathematics and Natural Sciences, Sebelas Maret University, Surakarta, Indonesia

E-mail: teguh@mipa.uns.ac.id

Received: 21 November 2022  Accepted: 8 May 2023

Abstract:

The present study investigates the growth synthesis, purification, and surface modification of long magnetic carbon nanotubes (Mag-CNTs). The synthesis was carried out by chemical vapor deposition (CVD) using Incoloy 800 as a catalyst material with a gas mixture of argon (Ar) and acetylene (C₂H₂). The CNTs growth directly on the Incoloy catalyst had magnetic properties and a multiwalled structure in millimeter length. The definitive diffraction peak of the crystal plane of carbon C(002) widened similarly to what was observed in commercial CNTs with several additional diffraction peaks from the iron oxides Fe₃O₄ and Fe₂O₃. After the synthesis, four various purification methods (A through D) were applied such as soaking using toluene and atmospheric heating at 100 °C for 2 h (A); vacuum annealing at 500 °C for 6 h (B); soaking using toluene followed by atmospheric heating and vacuum annealing (C); and similar to method C without atmospheric heating (D). The results show that a combination technique of method D was the best method for Mag-CNTs purification. Fourier transform infrared (FTIR) spectroscopy confirmed the O–H and Fe–O absorption peaks with significantly enhanced intensity after purification and plasma treatment. The plasma surface modification of Mag-CNTs was performed using plasma jets in different vapor gases of Ar/ethanol, Ar/acetic acid, and Ar/NH₃ with varied electrode distances. During the modification process, the plasma jet technique was able to add hydrophilic functional groups on the surface of Mag-CNTs, evidenced by the better dispersion properties compared with those before the plasma jet treatment. The use of Ar/NH₃ in the plasma treatment with a shorter electrode distance had the best effect compared to other gas mixtures for increasing the material's hydrophilicity.

Graphical Abstract

Keywords: Magnetic; Carbon nanotubes; Incoloy; Hydrophilic groups; Plasma jet

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02863-8

Chemical Papers 77 (9) 5305–5316 (2023)