Highly surface-active Si-doped TiO2/Ti3C2Tx heterostructure for gas sensing and photodegradation of toxic matters

Si@TiO2/Ti3C2Tx heterostructures were synthesized in situ from Ti3AlC2 MAX phase by a combination of high-temperature Si diffusion and HF etching. The optimal processing conditions and optimal structure were set up. For the optimal heterostructure, small TiO2 particles were distributed over Ti3C2Tx MXene with significantly increased surface area. Unlike Ti3C2Tx MXene, the Si@TiO2/Ti3C2Tx heterostructure behaved like a semiconductor. The heterostructure demonstrated superb 2,4-Dinitrophenol (DNP) photodegradation capability and good room-temperature NO2-sensing performance. In particular, the remarkable photocatalytic DNP degradation was explained on the basis of the broad-range light absorption and effective carrier separation by the Schottky contact. Furthermore, density-functional theory (DFT) calculations indicated that Si atoms might facilitate the NO2 adsorption process. The output of this work may highlight the potential of Si@TiO2/Ti3C2Tx heterostructure as a multi-functioning nanomaterial.

Automated summary

Si@TiO2/Ti3C2Tx heterostructures were synthesized in situ from Ti3AlC2 MAX phase by combining high-temperature Si diffusion and HF etching. The optimal heterostructure showed semiconductor behavior with enhanced surface area due to the distribution of small TiO2 particles over Ti3C2Tx MXene. The heterostructure exhibited excellent 2,4-Dinitrophenol photodegradation and room-temperature NO2-sensing capabilities, with the photocatalytic degradation attributed to broad light absorption and efficient carrier separation by Schottky contact. Density-functional theory calculations suggested that Si atoms could facilitate NO2 adsorption, highlighting the multi-functionality potential of Si@TiO2/Ti3C2Tx heterostructure.