2D layered MXene/TiO2 nano-heterostructures for photocatalytic H2 generation

Abstract

It is known that 2D MXene can be oxidized in air to form heterostructures of carbides, carbon, and oxides. We prepared MXene/TiO2 nano-heterostructures by in-situ thermal processing of MXene (Ti3C2Tx) at 250–400 °C temperature range in air. The structural studies by x-ray diffraction indicate the formation of MXene/TiO2 nano-heterostructures with increasing the annealing temperature above 300 °C and the resulting structure became mostly TiO2 after 400 °C annealing with no detectable MXene peaks in XRD patterns. The diffuse reflectance UV–Visible absorbance spectroscopy shows the blue shift in the absorbance profile of MXene from 720 to 380 nm by increasing the temperature. Photoluminescence spectra shows two emission peaks, the emission at 370 nm and 470 nm corresponds to band edge emission and oxygen defect, respectively. Raman analysis also supports the formation of MXene and TiO2 nano-heterostructures. Scanning and transmission microscopy results depict the formation-layered structures of MXene transformed into exfoliated sheet-like structures due to etching. The photocatalytic activity of formed nano-heterostructures was investigated for H2 generation via water splitting and aqueous methylene blue dye degradation. The nano-heterostructure formed at 350 °C conferred highest H2 production (366 μmol/0.1 g) as compared to other prepared compositions having apparent quantum yield (AQY) of 5.9% and shows MB degradation rate of 13.16 × 10–3 min−1.The formation of nano-heterostructures, particle morphology, higher surface area, the presence of remaining MXene might be responsible for higher photocatalytic activity. These MXene-based nano-heterostructures will have potentials along with other semiconductors for enhanced hydrogen production.Graphical abstract Schematic presentation of photocatalytic water splitting using Ti3C2Tx/TiO2 nano-heterostructure.