Synthesis, Characterization and Energy Applications of 2D Metal Carbides / Metal Nitrides

Abstract

Supercapacitors are in demand due to the growing market of flexible wearable electronics and energy storage devices. Only a few transition metal oxides and sulfides have been investigated and attained high-rate capability because of their lower electrical conductivity. MXenes, being a newborn 2D nanomaterial has drawn its attention in energy storage devices because of revolutionary properties and commercial applications. Despite all substantial investigations the research is still needed to be explored. Especially addressing the issues related to material stability in aqueous electrolyte. This thesis comprises of etching of d-Ti3C2, d-Ti3CN and d-Ti3N MXene from parent MAX phase. These new composite materials were prepared using in-situ growth of Ni3S4 nanoparticles on nitrogen doped delaminated Ti3C2 MXene via a hydrothermal method. d-Ti3C2 MXene was combined with different metal oxides (MoO3, V2O5) ionic liquid (1-Methyl-3-butyl imidazolium Bromide) using different method of synthesis (hydrothermal, sonochemical method). The phase development and surface morphology of these novel materials were systematically examined using a range of characterization techniques such as X-ray diffraction (XRD), Raman spectroscopy, FTIR (Fourier transform infrared spectroscopy) X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM), and scanning electron microscopy (SEM). The surface porosity and electrochemical properties were thoroughly studied using gas sorption and state of the art electrochemical techniques. MXene and its nanocomposites were tested for energy applications such as supercapacitors (SCs) and water splitting. N-Ti3C2@Ni3S4 showed electrochemical results with specific capacitance (Cs) of 1280 F g -1 at a current density of 1 A g-1 . d Ti3C2/MoO3@IL showed exceptional performances with Cs of 1680 F g-1 at 1 A g-1 . Ti3C2/MoO3 electrode possessing 2D/1D structure exhibits outstanding Cs of 624 F g -1 at 1 A g -1 . Similarly, d Ti3CN delivered an excellent Cs of 260 F g-1 at 1 A g-1 current density. A novel d-Ti3N MXene was synthesized and its electrochemical performance in supercapacitor application was checked. Moreover, a symmetric supercapacitor (SSC) device from N-Ti3C2@Ni3S4, d-Ti3C2/MoO3@IL, d-Ti3CN and d-Ti3N MXene demonstrated excellent energy and power densities. It was observed that d-Ti3C2/MoO3@IL showed excellent electrochemical performance than other synthesized materials. Ti3C2/MoO3 and d-Ti3C2/V2O5 showed excellent results for water splitting applications (HER, OER). The results proved that MXene based composites can act as an advanced electrode material for fabrication of portable electronic materials. This dissertation sheds light on the fabrication of high-efficiency electrode materials and addressed some of the basic issues related to MXene.