abstract
The Taguchi method with a parameter design L-9 orthogonal array was implemented for optimizing the nitrogen incorporation in the structure of vertically aligned N-doped CNTs grown by thermal chemical deposition (TCVD). The maximization of the I-D/I-G ratio of the Raman spectra was selected as the target value. As a result, the optimal deposition configuration was NH3 = 90 sccm, growth temperature = 825 degrees C and catalyst pretreatment time of 2 min, the first parameter having the main effect on nitrogen incorporation. A confirmation experiment with these values was performed, ratifying the predicted I-D/I-G ratio of 1.42. Scanning electron microscopy (SEM) characterization revealed a uniform completely vertically aligned array of multiwalled CNTs which individually exhibit a bamboo-like structure, consisting of periodically curved graphitic layers, as depicted by high resolution transmission electron microscopy (HRTEM). The X-ray photoelectron spectroscopy (XPS) results indicated a 2.00 at.% of N incorporation in the CNTs in pyridine-like and graphite-like, as the predominant species. (C) 2015 Elsevier B.V. All rights reserved.
keywords
CARBON NANOTUBE ARRAYS; NITROGEN; OPTIMIZATION; SPECTROSCOPY; STORAGE
subject category
Chemistry; Materials Science; Physics
authors
Silva, RM; Fernandes, AJS; Ferro, MC; Pinna, N; Silva, RF
our authors
Marta Ascenção Carmona Ferro
Laboratory Officer
Ricardo Manuel Fonseca Lopes da Silva
Junior Researcher
Rui Ramos Ferreira e Silva
Associate ProfessorProjects
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
RMNE-UA-National Network of Electron Microscopy (REDE/1509/RME/2005 )
acknowledgements
R.M. Silva is very grateful to FCT for the grant SFRH/BD/90844/2012. The X-ray photoelectron spectroscopy (XPS) analyses were done in the CEMUP at the University of Porto. The RNME - Pole University of Aveiro, FCT Project REDE/1509/RME/2005 is acknowledged. The authors would like to acknowledge Prof. Saveria Santagelo from University of Reggio Calabria for her critical reading of the manuscript and fruitful discussion. This work was developed in the scope of the project CICECO-Aveiro Institute of Materials (Ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement.