Probing Molecular Interactions at MXene-Organic Heterointerfaces

Here, using a combined theoretical and experimental approach, we have investigated the interaction mechanism of titanium carbide MXene with a variety of organic molecules whose end groups are O, S, N, and tertiary amines. All organic molecules intercalated between MXene layers; however, layer expansion followed the end group of the organic molecules. A broad range of optical spectroscopies confirmed that the nature of interactions/reactions of titanium carbide MXene with organic molecules is also end group-dependent that involve a variety of complex interactions between MXene and organic molecules such as electrostatic interactions, polymerization, strong binding, and in some cases catalytic decomposition of the organic molecules. First-principles calculations revealed that organic molecules tend to stay flat on the MXene surface during molecular assembly and that the binding and charge transfer from organic molecules to MXene occur, which are strongly end group-dependent, corroborating the experimental observations. The impact of interactions/reactions within the MXene-organic heterostructures on pseudocapacitance is further discussed.