Significant effect of base assisted intercalates in synthesis of 2D semiconductor Ti3C2O2

Theoretical chemists have predicted that Ti2CO2 and Ti3C2O2 possess an indirect bandgap that causes them to transform into semiconductors. However, few experiments have reported the appropriate bandgap for Ti3C2O2 and Ti2CO2. In this study, we first proved that Ti3C2O2 is a semiconductor by using a base-assisted intercalation method. A comprehensive study, including spectroscopy measurements, a computational approach, and mechanism analysis, established the efficacy of using a base. Results showed that Ti3C2O2 with a bandgap of 0.66 eV can be easily obtained after low-temperature annealing by using a novel base-assisted intercalation method. By contrast, such compound was hardly obtained when a solution intercalation procedure was used. The significant effect of the base was demonstrated in the synthesis procedure and the mechanism. The theoretical calculation predicted that Ti3C2O2 is a semiconductor with an indirect bandgap of 0.63 eV from the generalized gradient approximation. This prediction is consistent with the experimentally determined value.