Experimental and theoretical studies on the synergistic effect of P and Se co-doped g-C3N4 loaded with Ag nanoparticles as an affective photocatalyst under visible light irradiation

Abstract

In this work, in order to improve drawbacks of bare (pure) carbon graphite nitride (g-C3N4), phosphorus-selenium doped carbon nitride was synthesized to enhance light absorption in visible region. Then Ag nanoparticles loaded onto P-Se co-doped g-C3N4, as a result, the surface plasmonic resonance effect was created. In addition, the photocatalytic activity of samples was improved by suppression of charge carriers’ recombination. Synthesized photocatalyst was characterized by XRD, FT-IR, EDS, BET, XPS, FE-SEM, ICP, TEM, and DRS and PL analysis. All prepared samples were applied in the degradation of Rhodamine B as an azo dye under irradiation of visible light. According to the obtained results, the sample of Ag/P-Se co-doped g-C3N4 (3 wt% Ag, 2 wt% P and Se) showed the highest photocatalytic activity for the degradation of Rhodamine B (about 90% after 180 min). This result was about 4 times higher than degradation of dye in the presence of pure g-C3N4. This increase in the photocatalytic activity in Ag/P-Se co-doped g-C3N4is related to the significant decrease in bandgap energy due to the synergistic effects by doping P and Se, as well as the decrement in the recombination rate of electron-holes by depositing Ag nanoparticles. Quantum and Monte Carlo (MC) calculations were used to investigate the structure P-Se co-doped g-C3N4 and the interaction of Ag molecules on its surface under aqueous condition in the Materials Studio 2017 software. Ag created a tendency to form relatively strong interaction with synthesized P-Se co-doped g-C3N4. Also, Monte Carlo adsorption locator module was investigated to test adsorption activity of Rhodamine B on g-C3N4 and P-Se co-doped g-C3N4 loaded with Ag. According to the obtained outcomes, RhodamineB adsorption on P-Se co-doped g-C3N4 loaded with Ag structure was higher than the dye adsorption on g-C3N4 pure. In this structure, Ag atoms led to better dye adsorption on P-Se co-doped g-C3N4 surface (Rhodamine B was adsorbed on P-Se co-doped g-C3N4 surface by Ag atoms with lower than 3 Å). In addition, Rhodamine B was interacted by catalyst via π-π stacking interactions and hydrogen bonding. Furthermore, Ag atoms enhancedRhodamine B adsorption on P-Se co-doped g-C3N4 surface.