Agent free pillaring engineering of interlayer spacing of Ti3C2 MXene layers for energy conversion and photothermal desalination

Abstract

The interlayer stacking of two-dimensional (2D) nanomaterials hinders their application in energy-related fields. This work introduces a unique yet simple strategy to enhance the interlayer spacing of T₃C₂ MXene layers without adding foreign pillaring agents, using an in situ oxidation method. This strategy converts surface titanium into titanium oxide, which acts as a pillaring agent between the single layers while retaining the inherent 2D layered structure of MXene. This modification enhances the interlayer spacing and provides highly active centers of titanium oxide. Morphological and structural analyses confirm the formation of titanium oxide active centers and the consequent increase in interlayer spacing, making the material a more effective photocatalyst for CO₂ reduction and enabling simultaneous desalination through photothermal evaporation. The optimized in situ oxidized sample, Ti_xO₂(T_3-xC₂), outperforms pristine MXene by achieving a high solar desalination rate of 1.51 kg m⁻² h⁻¹ with a thermal efficiency of 85.3%. Additionally, under one-sun irradiation, the Ti_xO₂(T_3-xC₂) membrane exhibits a CO evolution rate of 60.67 μmol m⁻² h⁻¹. The superior photothermal effect and photocatalytic activity, compared to intrinsic MXene layers, are attributed to the higher interlayer spacing, which increases ionic conductivity, exposes titanium oxide metal active centers, and provides more active sites.