Preparation Of Unsubstituted Metal Phthalocyanine/Graphitic Carbon Nitride Functional Nanomaterials And Their Photoelectrochemical Performances And Applications

Graphitic carbon nitride（g-C₃N₄,hereinafter abbreviated as CN）because of its low cost,visible light response and chemical stability,has been widely used in the fields of catalysis and energy,etc.However,the study also found that CN exists many shortcomings such as slow electron transfer rate,fast photoinduced electron-hole recombination efficiency,especially insoluble in conventional solvents,which limits its further functionalization and application.In this thesis,a series of functionalized MPcs/CN（MPcs are FePc,VOPc and ZnPc,respectively）nanocomposites were prepared by utilizing the characteristics that unsubstituted metal phthalocyanine（MPcs）and CN can be dissolved in concentrated sulfuric acid,then,further explore its application in the field of catalysis and photoelectrochemical（PEC）sensing.The main research contents are as follows:1.A series of FePc/CN functional nanomaterials were prepared by using the solution phase method,the FePc/CN-0.3 composites with excellent performance were selected as catalysts,then the differences of photocatalytic and electrocatalytic properties before and after the composite were investigated.Using bisphenol A（BPA）as a degradant and FePc/CN-0.3 as a photocatalyst,it was found that the photocatalytic degradation efficiency of BPA by FePc/CN-0.3 nanocomposites were 6.4 and 1.7 times higher than that of FePc and CN,respectively.Studies on the mechanism of photocatalytic activity enhancement indicate that:under visible light irradiation,photocurrent intensity of FePc/CN-0.3 were 12.49 times and 16.75 times that of CN and FePc,respectively.This is due to FePc sensitizes the photochemical activity of CN and improves the photoelectron separation efficiency.Further using FePc/CN-0.3 as a catalyst,electrocatalytic oxygen reduction（ORR）study found that FePc/CN-0.3showed enhanced ORR activity,and the oneset potential of FePc/CN-0.3 was positively shifted by 52 and 174 mV with respect to FePc and CN,respectively.This is because theπ-πinteraction of FePc and CN improves the electrocatalytic activity of FePc.2.The prepared VOPc/CN functional nanomaterials as photoelectric active materials,studies have indicated that under under the sensitization of VOPc,the light absorption range of VOPc/CN extends to the visible-near-infrared region.The PEC signal of VOPc/CN nanocomposites were 2.7-fold and 12.42-fold increase compared to VOPc and CN monomer,respectively.Simultaneously,the photocurrent of VOPc/CN is 1.67 times that of FePc/CN,demonstrating that VOPc/CN has better photoelectrochemical performance after compound.This may be due to the non-planar VOPc has a shorter intermolecular distance and a largerπ-πoverlap,ultimately resulting in a higher mobility of charge carriers.Further,using VOPc/CN nanocomposite as the photoelectric response material and diclofenac（DCF）aptamer as the biometric identification element to construct the PEC biosensor,the sensor has high sensitivity,low detection limit（0.03 nM,S/N=3）and wide linear range（0.1⁵00 nM）,which can be used for DCF detection in tap water.3.The ZnPc/CN functional nanomaterials was used as photoelectric active materials.Studies showed that the introduction of ZnPc effectively extends the absorption wavelength range of CN.The photocurrent response of ZnPc/CN are 5.7times and 19.3 times that of ZnPc and CN,respectively,attributed to that ZnPc sensitized CN enhances the light-capturing ability of CN,inhibits its photoinduced electron-hole recombination,promote its charge separation and transfer,and thereby improving the photoelectric conversion efficiency.Simultaneously,the photocurrent of ZnPc/CN is 3.2 times higher than VOPc/CN,exhibiting better PEC activity.This is because in all MPcs,ZnPc has a longer excitation state lifetime,which is conducive to charge separation and transfer of excited states of ZnPc molecules.Furthermore,the PEC sensing platform was successfully established with ZnPc/CN as the photoelectric response material and sulfamethoxine（SDM）aptamer as the bio-identification molecule.The sensor showed excellent analytical performance in SDM detection with detection range of 0.1³00 nM and detection limit of 0.03 nM（S/N=3）,which can be used for sample detection in milk.