Synthesis of KBiO3/Nano-Ag3PO4 Composite Photocatalyst and Its Application for Degradation of Organic Pollutants under Visible Light

In this work, a novel composite photocatalyst, KBiO3/nano-Ag3PO4 (K/Ag catalyst), was synthesized, and efficiently degraded methylene blue (MB) under visible light. The various properties of photocatalysts were measured by modern analytical techniques, such as XRD, FT-IR, SEM, XPS, and UV-Vis. We also utilized Density functional theory calculation (DFT) to investigate the photocatalytic degradation mechanism in this reaction process. The multiple characterization findings demonstrated that K/Ag composite catalyst was successfully synthesized using Ag3PO4 and KBiO3, and it displayed excellent absorption of visible light. The photocatalytic results confirmed that K/Ag catalyst greatly promoted the degradation of MB under visible light. The first-order reaction kinetics model could satisfactorily describe the apparent photocatalytic degradation process in this system. In addition, adding electron capture agents to the photocatalytic system highly decreased the degradation efficiencies of the target pollutant. Moreover, K/Ag composite catalyst exhibited perfect photocatalyst stability after recycling three times. By calculating the band structure, Density of States (DOS), and work function, KBiO3 and Ag3PO4 could be considered as n-type and p-type semiconductor materials, respectively. When the composite catalyst was exposed to light, the light-excited electrons would have appeared in both the conduction bands. Furthermore, the transfer trend of electrons and holes made photogenerated electrons concentrate on the conduction band of n-type KBiO3, and photogenerated holes concentrate on the valence band of p-type Ag3PO4, thereby greatly improving the photocatalytic efficiency.