Effects of Concentration and Surface Termination on the Workfunction of Ti3C2X2 MXene (X=F,Cl,O,OH)
Authors: Villagracia Al Rey , Emralino Francis , Ong Hui Lin , Doong Ruey-An 
Published: August 2024

Titanium carbide (Ti3C2), belonging to the MXene family, has become a focal point of research due to its exceptional electronic and structural properties. As a two-dimensional transition metal carbide, Ti3C2 exhibits promising potential in a variety of applications, ranging from electronic devices to energy storage. Among the key parameters influencing its electronic behavior, the work function plays a pivotal role. This study aims to elucidate the intricate relationship between concentration, surface termination, and the work function of Ti3C2X2 through first-principles density functional theory (DFT) calculations. First-principles DFT calculations were employed to investigate the electronic structure of Ti3C2X2, focusing on the influence of varying concentrations of surface functional groups. Hydroxyl (-OH), oxygen (-O), chlorine (-Cl), and fluoride (-F) terminations were specifically chosen as representative functional groups for their prevalence in experimental studies and potential technological applications. These calculations provide a quantum-level understanding of the electronic properties and behaviors of Ti3C2 under different surface conditions. Our results indicate a notable sensitivity of the work function of Ti3C2 to changes in both concentration and the type of surface termination. The presence of functional groups induces charge redistribution within the MXene layers, significantly impacting the overall electronic landscape. The variation in charge distribution directly correlates with changes in the work function, illustrating the dynamic nature of Ti3C2 in response to surface modifications. Furthermore, an in-depth analysis of the correlation between concentration, surface termination, and the energetics of charge transfer at the Ti3C2 surface provides valuable insights. The interplay between these factors reveals intricate mechanisms that govern the observed variations in the work function. The concentration-dependent charge transfer at the surface serves as a key determinant, emphasizing the importance of carefully tailoring the composition to achieve desired electronic properties. The understanding gained from this study has significant implications for the tailored design and utilization of Ti3C2 in various technological applications. By manipulating concentration and surface termination, researchers and engineers can fine-tune the work function to meet specific requirements in electronic devices, sensors, and energy storage systems. This level of control over electronic properties enhances the versatility and applicability of Ti3C2 in emerging technologies. In conclusion, our investigation highlights the critical roles of concentration and surface termination in modulating the work function of Ti3C2. The pronounced sensitivity of this parameter to surface modifications underscores the need for a comprehensive understanding of the underlying electronic mechanisms. By elucidating the interplay between concentration, surface termination, and charge transfer, this study provides valuable insights that pave the way for the strategic design and implementation of Ti3C2 in advanced technological applications. The ability to fine-tune electronic properties opens new avenues for exploiting the full potential of Ti3C2 in diverse fields, driving innovation and progress in materials science and technology.