BiPO₄/Ag₃PO₄/Bi₂SiO_{5 heterojunction: controllable synthesis and its enhancement of visible light catalytic activity}

BiPO4/Ag3PO4/Bi2SiO5 heterojunction was synthesized by ultrasound assisted precipitation method combined with annealing. The crystal structure, morphology, specific surface area and optical properties of the nanocomposite were characterized by XRD, SEM, TEM, EDS, XPS, BET, PL, EIS, UV-Vis DRS. It can be observed by SEM and TEM images that BiPO4/Ag3PO4/Bi2SiO5 is composed of nanoparticles, nanorods and nanosheets. After irradiation for 40 min with a 70 W metal halide lamp, the degradation efficiency of 10 mg/L RhB and MO by BiPO4/Ag3PO4/Bi2SiO5 was 99.84% and 82.93%, respectively. COD test results showed that 75.92% of RhB was degraded to inorganic small molecules after 50 min of 70 W metal halide lamp. The results showed that BiPO4/Ag3PO4/Bi2SiO5 has excellent photocatalytic activity and recycle stability, which may be due to the construction of heterojunction resulting in stronger visible light absorption capacity and higher photogenerated electron-hole pair separation rate. Free radical capture experiments confirmed that h(+) and center dot O-2(-) were the main active species.