CsPbBr3 nanocrystals supported on a partially oxidized Ti2N MXene for photothermal CO2 conversion

Abstract

The development of new photo-thermal catalysts for the transformation of CO₂ into fuels is of great interest, offering a clean and sustainable approach to reducing the carbon footprint. Herein, we present a novel hybrid material composed of a nanocrystalline metal halide perovskite (CsPbBr₃) supported on a two-dimensional titanium nitride (Ti₂N) MXene. Additionally, we demonstrate the importance of forming an external TiO₂ layer through partial oxidation of the MXene (POM–Ti₂N), which introduces catalytic centers and enhances photogenerated charge separation. Remarkable activity in the formation of CH₄ and CO was observed, with yields of 321 µmol g⁻¹ and 480 µmol g⁻¹, respectively. The selectivity of the reaction was found to be temperature dependent. The mechanism was thoroughly investigated using XPS and photoluminescence studies. XPS analysis revealed a significant chemical interaction between the CsPbBr₃ nanocrystals and the POM–Ti₂N MXene after the formation of the composite. Photoluminescence measurements revealed a considerably shorter emission lifetime for the hybrid catalyst (τ_ave = 1.73 ns) compared to that of the CsPbBr₃ nanoparticles (τ_ave = 25.32 ns), indicating strong interaction with the MXene. Furthermore, this research highlights the potential of combining metal halide perovskites with MXenes and the importance of controlling their interface for photo-thermal reactions.