Porphyrin Sensitized Two-dimensional ZnO And CuO Nanomaterials And Thire Photocatalytic Selectivities Under Visible Irradiation

As a photocatalyst,there are many defects for CuO and ZnO semiconductors,such as low utilization of visible light,recombination of photo-generated charges,and without selectivity when organic pollutants were degraded.Because of these,they have been limited in photocatalytic field.For ZnO and CuO semiconductors,their light absorption spectra could be broaden by modified by photosensitizer,effective separation of photo-generated charges be achieved and selective photocatalysis presents towards the target pollutant.In this work,three kinds of nanocomposites were prepared,and their surfaces presented in different degrees of hydrophobicity or hydrophilicity.And thus,their photocatalytic selectivity was researched.The results were as follows:(1)By hydrothermal method,two-dimensional nest-like ZnO nanoplate(ZnO NAs)was synthesized on the ITO conductive glass.The exposed facets of ZnO NAs are(001)and(110).The diameter of single nest-like ZnO is 2um,and the thickness of every nanoplate is 60nm.The unsaturated coordination Zn-bonds as template,and tetraphenylporphyrin(H2TPP)as precursor,then the Zn-coordinated into the center of the porphyrin ring,formed monolayer of zinc tetraphenylporphyrin(ZnTPP)on the surface of ZnO NAs via in-situ method.ZnTPP and ZnO NAs fitted together by chemical bond(Zn-O),induced significantly fluorescence quenching(-62.1%),and achieved effective separation of electron-hole pairs.The surface of hydrophilic ZnO NAs(t=15s,contact angle(CA)=28.8°)was modified by hydrophobic ZnTPP,and then the surface of ZnTPP/ZnO NAs exhibited hydrophobicity(t=15s,CA=111.3°).Under visible light irradiation,the degradation rate of hydrophilic dyes rhodamine b(RhB)and hydrophobic substrates phenol(PL)by ZnTPP/ZnO NAs was 0.8 times and 3.12 times than that of ZnO NAs,respectively.In addition,the degradation rate in the mixture of RhB and PL by ZnTPP/ZnO NAs was 5.14 times for PL molecule to RhB,exhibiting obvious selective photocatalysis to hydrophobic organic dyes.(2)The unsaturated coordination Zn-bonds as template,and four sodium sulfonate phenylporphyrinthe(TPPS4)as precursor,zinc four sodium sulfonate phenylporphyrin(ZnTPPS4)was successfully synthesized on the surface of ITO with ZnO NAs thin film by in-situ substitute method.It happened significantly fluorescence quenching(?60.65%),and achieved effective separation of electron-hole pairs.Hydrophilic ZnO NAs was modified by hydrophilic ZnTPPS4,then the surface of ZnTPPS4/ZnO NAs exhibited super-hydrophilicity(t=15s,CA=0°).Under visible irradiation,the degradation rate of RhB and PL by ZnTPPS4/ZnO NAs was 1.18 times and 1.12 times than that of ZnO NAs,respectively.In addition,the degradation rate in mixture of RhB and PL by ZnTPPS4/ZnO NAs was 3.22 times for RhB molecule to PL,exhibiting obvious selective photocatalysis hydrophilic organic dyes.(3)By homogeneous precipitation method,two-dimension of flower-like CuO(CuO NFs)was obtained on the surface of ITO conductive glass.Cu-unsaturated on the surface of CuO NFs as a template,and H2TPP as precursor,formed monolayer of copper tetraphenylporphyrin(CuTPP)on the surface of CuO NFs via in-situ substituted method.Compared with CuO NFs(t=15s,CA=75.3?),CuTPP/CuO NFs nanocomposite presented super-hydrophobicity(t=15s,CA=143°).Under visible irradiation,the degradation rate of RhB and PL by CuTPP/CuO NFs was 1.54 times and 5.08 times than that of CuO NFs,respectively.It showed obvious selective photocatalysis hydrophobic organic dyes.The characterization of selective photocatalysis is owing to the target pollutant selectively absorbed onto the surface of photocatalyst.