Effect of organic solvents on in-situ growth of defective TiO2 from Ti3C2TX MXene nanosheets for photocatalytic NO abatement

Using solvothermal methods to in situ oxidize two-dimensional titanium carbide (Ti3C2TX) MXene into TiO2 -nanocrystals offered an effective strategy to construct highly efficient TiO2/Ti3C2TX heterojunctions for photo -catalytic applications. Nevertheless, the effect of the chosen solvent on the Ti3C2TX oxidation and the product's performance was often neglected. Herein, isopropanol (ISO), ethanol (EtOH), ethylene glycol (EG), dimethyl sulphoxide (DMSO) and deionized water (Water) were taken as the representative solvents to prepare TiO2/ Ti3C2TX composites by one-step solvothermal method for photocatalytic NO emission. It was the large polarity, dielectric constant and surface tension of the solvents that offered Ti3C2TX with good dispersibility and high oxidation degree during the solvothermal process. More importantly, the solvothermal treatment of Ti3C2TX in DMSO could promote the formation of TiO2 nanoparticles with obviously higher crystallinity and more surface oxygen vacancies than those in EG, EtOH and ISO. Therefore, the photocatalytic NO oxidation efficiency of the samples within 30-min irradiation showed a descending order of TT-DMSO (46.9%), TT-Water (42.2%), TT-EG (32.3%), TT-EtOH (26.7%), and TT-ISO (19.9%). This work highlighted the significance of oxidation environ-ment for Ti3C2TX, which could bring about some new but necessary consideration on the processing technique of MXene families for their future practical applications.