A visible light driven AgBr/g-C3N4 photocatalyst composite in methyl orange photodegradation: Focus on photoluminescence, mole ratio, synthesis method of g-C3N4 and scavengers

A visible light driven nanocomposite containing AgBr and sheet-like g-C3N4 was prepared by precipitation of AgBr nanoparticles (NPs) onto the surface of g-C3N4 nano-sheets. The composite system showed a significant enhancement in photocatalytic activity with respect to the mono-component systems in the degradation of methyl orange (MO) under visible light irradiation. Different methods including, bulky, thermal oxidation, protonation, and ultra-sonication were used for synthesis of g-C3N4 nanosheets. The resulted g-C3N4 samples were then modified by AgBr NPs via deposition-precipitation (DP) method. Among them, the catalyst containing the 'protonated g-C3N4' showed the best photocatalytic activity. The composite with AgBr:g-C3N4 mole ratio of 2:1 containing the 'protonated g-C3N4' showed the best activity. Different coupling techniques including: 'grinding', 'grinding-ultra-sonication', 'ultra-sonication/deposition-precipitation' and 'ultra-sonication/deposition-precipitation/ultra-sonication' were used for coupling of the protonated g-C3N4 with AgBr NPs. Among these catalysts, two later cases showed the best photocatalytic activities. Among the type II- heterojunction and the direct Z-scheme mechanisms, later case well described the boosted photocatalytic activity of the composite with respect to the mono-component systems.