Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C_3N_4 nanosheets

Exfoliation of bulk graphitic carbon nitride(g‐C3N4)into two‐dimensional(2D)nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g‐C3N4 nanosheets(CN)have larger specific surface areas and more reaction sites.In addition,poly‐o‐phenylenediamine(PoPD)can improve the electrical conductivity and photocatalytic activity of semiconductor materials.Here,the novel efficient composite PoPD/AgCl/g‐C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach.The obtained photocatalysts have larger specific surface areas and could achieve better visible‐light response.However,silver chloride(AgCl)is susceptible to agglomeration and photocorrosion.The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density,which is three times that of CN.Obviously enhanced photocatalytic activities of PoPD/AgCl/g‐C3N4 are revealed through the photodegradation of tetracycline.The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly.Furthermore,.O2^-and h+are the main active species,which are confirmed through a trapping experiment and ESR spin‐trap technique.Therefore,the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst,in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles.This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.

Thermo-responsive functionalized PNIPAM@Ag/Ag3PO4/CN-heterostructure photocatalyst with switchable photocatalytic activity

It is extremely important for photocatalysts to exhibit intelligent responsiveness to their environment. Herein, a poly N-isopropyl acrylamide(PNIPAM)-modified Ag/Ag3PO4-20/CN hybrid material with excellent convertible photocatalytic activity is prepared. PNIPAM has good hydrophilicity below the lower critical solution temperature(LCST);this increases the capacity of the photocatalyst for adsorbing tetracycline(TC) molecules. In addition, the PNIPAM-modified Ag/Ag3PO4-20/CN can prevent the loss of Ag3PO4. The dispersity is improved by loading g-C3N4 nanosheets(CN) for enhancing the efficiency of photocatalytic activity. Furthermore, a Z-scheme heterostructure is formed between CN and Ag3PO4, accelerating the separation efficiency of the holes and electrons. Ag nanoparticles can be used as electron-shuttle mediators, and electrons receiving more energy are transferred via the localized surface plasmon resonance(LSPR) effect. Furthermore, the PNIPAM@Ag/Ag3PO4-20/CN photocatalyst exhibits an excellent degradation rate for the degradation of TC when the temperature is lower than the LCST. The photoluminescence spectra and photocurrent curves prove that the carrier-separation efficiency of PNIPAM@Ag/Ag3PO4-20/CN is higher than those of Ag/Ag3PO4/CN and CN. The main active species of ·O2-and h+ are detected to reveal the plausible mechanism of the PNIPAM@Ag/Ag3PO4-20/CN hybrid material system. This work provides a way to develop intelligent materials for switchable photocatalytic applications.