Preparation Of Visible-light Photocatalyst With G-C₃N₄ As Main Precursor

An efficient visible-light photocatalyst was successfully synthesized by surface-hybridizing graphitic carbon nitride(g-C3N4)using a small amount of cadmium sulfide(CdS)nanoparticles.The synthesized samples were characterized by X-ray diffraction(XRD),Raman spectroscopy(Raman),UV-vis diffuse reflection spectroscopy(DRS),photoluminescence spectroscopy(PL),Electrochemical impedance spectra(EIS),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),and scanning electron microscopy(SEM).The results reveals that a small amount of CdS nanoparticles do not change the chemical composition and crystalline of g-C3N4,while obviously improve the visible-light absorption and electron-hole separation efficiency of CdS/g-C3N4 nanocomposites.With Rhodamine B(RhB)as the model pollutant,the visible-light photocatalytic activity and stability of CdS/g-C3N4 nanocomposites were investigated by evaluating the decomposition of RhB under visible-light irradiation.The effects of the CdS content on the nanocomposites,initial RhB concentrtation,pH value of the investigated system and dosage of CdS/g-C3N4 nanocomposites on the visible-light photocatalytic activity were systematically investigated.The results reveal that g-C3N4 surface-modified by a small amount of CdS nanoparticles exhibits excellent visible-light photocatalytic activity and stability.The visible-light photocatalytic activity of the nanocomposite photocatalysts increases as both CdS content on the nanocomposites and dosage of CdS/g-C3N4 nanocomposites increase,while increases at first and then decreases as both initial RhB concentrtation and pH value of the investigated system increase.The capture agent experiments indicate that the superoxide radical·O2-might be the main active species in RhB photodegradation.A new g-C3N4 photocatalyst modified by hydrogen peroxide(H2O2)was prepared via dipping method.The residual groups such as-NH2 and-NH-in g-C3N4 were oxidized by H2O2.The,visible-light absorption and the electron-hole separation efficiency of the modified g-C3N4 have been improved significantly,leading to the enhanced visible light photocatalytic activity of g-C3N4.