Preparation And Photocatalytic Properties Of Two-Dimensional Titanium Carbide-Based TiO₂ Nanocomposites

Recent years,photocatalytic technology has attracted extensive attention due to severe environmental problems.TiO₂ with better photocatalytic performance is one of the photocatalysts,but it also has problems such as wide band gap,low light absorption efficiency and easy photoelectron recombination.MXene-Ti₃C₂ two-dimensional layered nanomaterials have been widely used in the preparation of composite materials.In this work,a series of Ti₃C₂-based TiO₂nanomaterials were synthesized with Ti₃C₂ as the matrix,and their photocatalytic degradation properties were studied as well.The main research contents and results are presented as follows:（1）TiO₂/Ti₃C₂ composites were prepared by in-situ self-oxidation of Ti elements contained in the matrix Ti₃C₂.The morphology of the composite was improved by changing different acid and alkali conditions.Thus,its photocatalytic performance can be improved.The results show that the composite materials prepared under acidic conditions have the best photocatalytic degradation performance,and the photocatalytic reaction rate constant k value of 0.05 g TiO₂/Ti₃C₂（CH₃COOH）is 0.0370min^-1.（2）In order to further improve the photocatalytic performance of TiO₂/Ti₃C₂composite prepared by self-oxidation,Cu₂O,which has a small band gap and can absorb visible light wavelength,was introduced.The composite was expanded to a ternary system,and a Cu₂O/TiO₂/Ti₃C₂ ternary composite was prepared by normal temperature stirring method and hydrothermal method.According to experiments,the photocatalytic properties of hydrothermal prepared Cu₂O/TiO₂/Ti₃C₂ ternary composites have been certainly enhanced compared with the binary composite material,its reaction rate constant was 0.02037 min^-1.The possible reason is that the presence of reductant PVP in hydrothermal reaction leads to a small amount of Cu elemental substance generated.So that the electron transfer efficiceny of Cu₂O/TiO₂/Ti₃C₂ ternary composite is increseased.Besides,the addition of cuprous oxide particles increases the specific surface area of the composite material,the active site and the contact area between photocatalyst and dye.（3）Due to the limitations of Ti₃C₂ self-oxidation,the photocatalytic performance of the composite material needs to be further improved.Ti₃C₂/TiO₂composite material was prepared by hydrothermal method.In this method,TiO₂is supported on Ti₃C₂ laminates,using butyl titanate as the titanium source,and Ti₃C₂/TiO₂ composite material photocatalytic performance was studied.The results showed that the photocatalytic effect was greatly improved.The photocatalytic reaction rate constant k value of 0.03 g TiO₂/Ti₃C₂ composite was0.0277 min^-1,and its specific surface area was about 17.54 times than Ti₃C₂.This is because that the improvement of specific surface area and the synergistic effect of TiO₂ and Ti₃C₂ may increase the photocatalytic performance.（4）To enhance the photocatalytic performance based on adding external titanium sources,the precious metal Ag was introduced to expand the binary material TiO₂/Ti₃C₂ with titanium sources to ternary material,and the ternary nanocomposite of Ag/TiO₂/Ti₃C₂ was prepared.The results showed that it had a good photocatalytic effect.At the second sampling,the degradation efficiency reached 90%,and the photocatalytic reaction rate constant k value was 0.05205min^-1.The photocatalytic performance of ternary composites may be improved by the plasma effect of Ag.