Structural Modulation Of TMP Conjugated Polymer And Its Effect On The Photocatalytic Performance Of TMP-TiO₂

The photocatalytic activity of titanium dioxide（TiO₂）is largely hindered by its low photoreactivity and quantum efficiency.Modification of TiO₂ with conjugated polymers（CPs）is considered as a promising approach to improve the visible light responsiveness of TiO2.In this work,to investigate the effect of structural changes of CPs on the photocatalytic performance of TiO₂ in visible light,htrimesoyl chloride–melamine polymers（TMPs）with different structures and properties were synthesised by varying the conditions of the polymerisation process of melamine（M）and tricarbonyl chloride（TMC）.Subsequently,the composites（TMP-TiO₂）were obtained by compounding TMP with TiO₂ using in situ hydrothermal technique.Through the degradation of the target pollutant rhodamine B（Rh B）by TMP-TiO₂,the effect law of structural changes of the TMP conjugated polymer on the photoresponsiveness and photocatalytic performance of TiO₂ under visible light was investigated,providing a new idea to optimize the photocatalytic performance of the composite catalyst.The main research contents and results are as follows:（1）By changing the reaction ratio,reaction temperature and reaction time in the polymerization process of melamine and tricarbonyl chloride,the structure of TMP was modulated and tricarbonyl chloride melamine polymers with different functional group properties,crystal structure,π-conjugation effect,morphology,band gap and electrochemical impedance were successfully synthesized.The results of the structural modulation of the TMP polymers were elaborated through the analysis of the characterization results of FT-IR,XRD,SEM,TEM,UV-Vis DRS,EIS and CV.The results showed that the amide bond strength,crystallinity andπ-conjugation effect of TMP tended to increase and then decrease with increasing the reaction ratio,reaction temperature and reaction time of melamine and tricarbonyl chloride.（2）TMP-TiO₂ was obtained by compounding TMP with TiO₂ using an in situ aqueous method.The effects of structural changes of the TMP conjugated polymer on the photoresponsiveness and photocatalytic performance of TiO₂ under visible light were investigated by the degradation of the target pollutant Rh B by TMP-TiO₂,providing a new idea for optimising the photocatalytic performance of the composite catalyst.The results showed that the structure of TMP further influenced the visible light responsiveness and photocatalytic performance of the TMP-TiO₂ complex after TMP was compounded with TiO₂,and the trends of the functional group properties,crystal structure,π-conjugation effect,morphology,band gap and electrochemical impedance of TMP with the reaction conditions were consistent with the visible light responsiveness of TMP-TiO₂,and as the amide bond strength,crystallinity The visible light responsiveness of TMP-TiO₂ and the efficiency of photocatalytic degradation of rhodamine B increased as the amide bond strength,crystallinity andπ-conjugation effect of TMP increased.As the band gap of TMP decreases,the band gap of TMP-TiO₂ decreases and the elevation of the valence band top becomes greater.As the electrochemical impedance decreases,the visible light responsiveness of TMP-TiO₂and the efficiency of photocatalytic degradation of rhodamine B increase.Among them,TMP（1:1）-TiO₂ had the best photocatalytic activity and could degrade 96.1%of Rh B.