Effect of Nitrogen Doping on the Optical Bandgap and Electrical Conductivity of Nitrogen-Doped Reduced Graphene Oxide.

Gunawan Witjaksono,Nelson Tansu,Saeed S Ba-Hashwan,Mohd Haris Khir,Muhammad Junaid,Muhammad Zubair Aslam,Abdullah Saleh Algamili,Zaka Ullah,Saeed Ahmed Magsi,Muhammad Aadil Siddiqui,Mohamed Shuaib Bin Mohamed Saheed,Rab Nawaz

doi:10.3390/molecules26216424

Abstract

Graphene as a material for optoelectronic design applications has been significantly restricted owing to zero bandgap and non-compatible handling procedures compared with regular microelectronic ones. In this work, nitrogen-doped reduced graphene oxide (N-rGO) with tunable optical bandgap and enhanced electrical conductivity was synthesized via a microwave-assisted hydrothermal method. The properties of the synthesized N-rGO were determined using XPS, FTIR and Raman spectroscopy, UV/vis, as well as FESEM techniques. The UV/vis spectroscopic analysis confirmed the narrowness of the optical bandgap from 3.4 to 3.1, 2.5, and 2.2 eV in N-rGO samples, where N-rGO samples were synthesized with a nitrogen doping concentration of 2.80, 4.53, and 5.51 at.%. Besides, an enhanced n-type electrical conductivity in N-rGO was observed in Hall effect measurement. The observed tunable optoelectrical characteristics of N-rGO make it a suitable material for developing future optoelectronic devices at the nanoscale.

Highlights

The heteroatom atom doping of carbon-based nanomaterial, i.e., graphene, graphene oxide, and carbon nanotube, among others, has gained great attention in material science and research [1]
The pyrrolic-N bonding configuration in nitrogen-doped reduced graphene oxide (N-rGO) material samples was more dominant in X-ray photoelectron spectroscopy (XPS) analysis, which enhances the π-bond in carbon atoms by reducing the Stone–Wales effect and forming percolation ways for electrons, which results in quitting a conduction gap and enhancing n-type electrical conductivity
The successful synthesis of GO and N-rGO was confirmed by Raman, FTIR, X-ray diffraction (XRD), XPS, field emission scanning electron microscopic (FESEM), and EDX mapping and spectroscopic techniques

Summary

Introduction

The heteroatom atom doping of carbon-based nanomaterial, i.e., graphene, graphene oxide, and carbon nanotube, among others, has gained great attention in material science and research [1]. Certain extrinsic characteristics of chemically modified graphene have been investigated in several applications such as sensors [4], energy harvesting [5], supercapacitors [6], field-effect transistors [7], and solar cells [8]. Certain optical and electronic properties of graphene, and modified graphenebased material, such as chemical stability, optical saturation, high charge carrier mobility, transparency, and intrinsic zero bandgap nature with tunable bandgap ability, enable graphene-based materials to perform efficiently for the development of forthcoming optoelectronic devices [9]. Pristine graphene is a zero-bandgap material, where the energy bandgap can be manipulated for several applications, including photolytic activities and solar cells [10]

Methods

Results

Conclusion