Synthesis and characterization of type-II p(CuxSey)/n(g-C3N4) heterojunction with enhanced visible-light photocatalytic performance for degradation of dye pollutants

The current work investigated a synergetic effect of graphitic carbon nitride (g-C3N4) with different concentrations (5, 10, 1nd 15 w%) on the visible-light photocatalytic activity of the copper-selenide (CuxSey) nanostructures. Morphology and structure of the nanostructures were CuSe hexagonal nanodiscs decorated with Cu3Se2 nanoparticles (NPs). UV-vis spectra showed a higher absorption intensity for the CuxSey/g-C3N4 nanocomposites. Mott-Schottky (MS) experiments indicated a p-type behavior for the CuxSey nanostructures forming a p-n heterojunction with n-type g-C3N4. The photocatalytic activity measurements showed that the g-C3N4 with a 5% concentration had a significant synergetic role to improve the photocatalytic performance of the nanostructures. Brunauer-Emmett-Teller (BET) indicated the samples included mesostructure but the g-C3N4 could not improve their textural properties. The Fermi level offset of the p-n heterojunction led to an internal electric field caused the electrons and holes to move in opposite directions. Thus we encountered with a strong electron-hole separation in this heterojunction. This was the most important factor to enhance the photocatalytic performance of the CuxSey/g-C3N4. Finally, the examination of the photocatalytic activity showed that the hydroxyl radicals (%OH) were the most important factors during the redox process of the dye.