Tunable Electronic Property of Cr₂TiC₂Tx MXene: Insights from Density Functional Theory

MXenes, a rapidly growing class of two-dimensional materials, are known for their diverse electronic, mechanical, and optoelectronic properties. Among these, double-transition-metal MXenes, such as Cr₂TiC₂Tx, offer even greater tunability in their properties due to the presence of two distinct transition metals. Cr₂TiC₂Tx stands out as a unique material among the MXenes experimentally tested, exhibiting p-type conductivity and a positive photoresponse. In this work, we performed density functional theory calculations to investigate the tunability of the electronic properties of Cr₂TiC₂Tx. We systematically examined the effects of Cr vacancies, oxygen substitution at carbon sites, and surface terminations. Our results show that Cr vacancies enhance p-type conductivity while oxygen substitutions induce n-type behavior, demonstrating tunable p-/n-type conductivity. These theoretical insights, supported by experimental findings, illustrate Cr₂TiC₂Tx as a promising material for advanced electronic and optoelectronic applications.