Nb-Doped MXene With Enhanced Energy Storage Capacity and Stability.

Mahjabeen Fatima,Jameela Fatheema,Amjad Islam,Ahmad Hassan Siddique,Deji Akinwande,Bushra Khan,Syed Rizwan,Nasbah B Monir

doi:10.3389/fchem.2020.00168

Abstract

MXenes present unique features as materials for energy storage; however, limited interlayer distance, and structural stability with ongoing cycling limit their applications. Here, we have developed a unique method involving incorporating Nb atoms into MXene (Ti3C2) to enhance its ability to achieve higher ionic storage and longer stability. Computational analysis using density functional theory was performed that explained the material structure, electronic structure, band structure, and density of states in atomistic detail. Nb-doped MXene showed a good charge storage capacity of 442.7 F/g, which makes it applicable in a supercapacitor. X-ray diffraction (XRD) indicated c-lattice parameter enhancement after Nb-doping in MXene (from 19.2A° to 23.4A°), which showed the effect of the introduction of an element with a larger ionic radius (Nb). Also, the bandgap changes from 0.9 eV for pristine MXene to 0.1 eV for Nb-doped MXene, which indicates that the latter has the signature of increased conductivity due to more metallic nature, in support of the experimental results. This work presents not only the effect of doping in MXene but also helps to explain the phenomena involved in changes in physical parameters, advancing the field of energy storage based on 2D materials.

Highlights

In the last decade, chemical processes have been developed to successfully produce a versatile family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, termed MXenes, from their parent layered MAX phases (Lei et al, 2015)
MXene but has decreased intensity in Nb-doped MXene, which is the result of the doping
The presence of Nb in MXene has decreased the intensity of the MXene peak, which indicates that the amount of lattice defects has been increased (Tarascon and Armand, 2001)

Summary

INTRODUCTION

Chemical processes have been developed to successfully produce a versatile family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides, termed MXenes, from their parent layered MAX phases (Lei et al, 2015). The MAX titanium aluminum carbide is a layered, hexagonal carbide, or nitride form of compound, having the general formula “Mn+1AXn”, Nb-Ti3C2 for Enhanced Energy Storage where n = 1, 2, 3 and where M is a transition metal, A is an A-group element, and X represents carbon or nitrogen or a combination of both (Shein and Ivanovskii, 2013). This article reports on an experimental and computational study of the effect of Nb-doping of Ti3C2 MXene from structural and morphological perspectives and for energy storage applications, such as in supercapacitors and lithium-ion batteries. The solution was rinsed with ethanol and deionized water three times, and extraction of precipitate was performed by vacuum filtration It was dried in a vacuum at 80◦C for 24 h to obtain the powdered form of the desired material.

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT