Investigating Properties And Applications Of G-C₃N₄ Through NaHSO₃ Induced Chemiluminescence

As a carbon nitride conjugated polymer semiconductor material,g-C₃N₄ has received widespread attention.Currently,most of the researches are focused on the development of the application of g-C₃N₄ materials,few scientists pay attention to investigate the properties of g-C₃N₄ materials by new methods.Chemiluminescence?CL?reaction is a redox process accompanying with electron transfer,so it can be applied to study the photoelectric properties with electron transfer of the material.This thesis established a new CL system of g-C₃N₄-NaHSO₃,which was employed to study the properties of electron donor,CO₂ activation and metal ion adsorption of bulk g-C₃N₄,g-C₃N₄ nanosheets and carbon nitride quantum dots?CNQDs?.The main contents are summarized as follows:?1?The bulk g-C₃N₄-NaHSO₃ ultra-weak CL system was established,and it was found that the CL intensity could be enhanced by NaHCO₃.Based on the ESR spectra,it was found that g-C₃N₄ could transfer an electron to the dissolved oxygen in solution to produce·O₂^-anion radical,and g-C₃N₄ could also convert NaHSO₃ to·SO₃^-anion radical.The formation of·SO₃^-anion radical could be promoted by activated CO₂.The emitter of the system was SO₂*rather than?CO₂?₂*leading the enhancement of CL,which was confirmed by CL spectra.The activated CO₂ enhanced the CL intensity,so CL method can be used to evaluate the activation ability of CO₂ of material through the CL intensity.?2?The preparation of g-C₃N₄ nanosheets by ultrasonic assisted solution stripping technique was introduced,and the g-C₃N₄ nanosheets-NaHSO₃ ultra-weak CL system was established.The effects of Cu????Fe???????Mn????Cr????Pb????Zn????Ni???and Co???metal ions to the CL system were studied.The results showed that Cu????Fe???????Mn????Cr???and Pb???could enhance the CL intensity,which was significantly different from that the fluorescence of g-C₃N₄ nanosheets could be quenched by Cu²⁺.The ESR spectra showed that·OH was generated when g-C₃N₄nanosheets mixed with Cu????Fe???and Mn???ions,which was the important reason for CL enhancement.?3?CNQDs were prepared by hydrothermal method with melamine as the raw material.It was found that CNQDs-NaHSO₃ CL system could produce strong luminescence in alkaline medium.And based on the fluorescence spectroscopy,ESR spectroscopy,CL spectroscopy and radical scavenger experiment,it was easy to get that alkaline environment was favorable for the generation of·OH radicals and CRET happened between SO₂*and CNQDs.Compared with bulk and nanosheets material,zero-dimensional scale quantum dots were more easily to have CRET reaction.What's more,the concentration of NaHSO₃ in the system could also be linearly related to the intensity of CL in a certain rang.