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 (Ti 3 C 2 T x ) MXene into TiO 2   nanocrystals offered an effective strategy to construct highly efficient TiO 2 /Ti 3 C 2 T x   heterojunctions for photocatalytic applications. Nevertheless, the effect of the chosen solvent on the Ti 3 C 2 T x   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 TiO 2 /Ti 3 C 2 T x   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 Ti 3 C 2 T x   with good dispersibility and high oxidation degree during the solvothermal process. More importantly, the solvothermal treatment of Ti 3 C 2 T x   in DMSO could promote the formation of TiO 2   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 environment for Ti 3 C 2 T x , which could bring about some new but necessary consideration on the processing technique of MXene families for their future practical applications.