Microwave-assisted hydrothermal synthesis of broadband Yb3+/Er3+ co-doped BiOI/Bi2O4 photocatalysts with synergistic effects of upconversion and direct Z-scheme heterojunction

Constructing full spectrum photocatalyst is an effective strategy to improve the conversion efficiency of solar energy. In this work, BiOI:Yb 3+ ,Er 3+ /Bi 2 O 4 (BYE/BO) direct Z-scheme heterojunction photocatalysts were successfully synthesized by a fast and simple microwave-assisted hydrothermal method. XRD, XPS, FE-SEM, TEM, PL, DRS, and BET were used to investigate the physical and chemical properties of samples. Compared to pure BYE and BO, as-synthesized BYE/BO samples had significantly improved photocatalytic activity in the degradation of Ciprofloxacin and Rhodamine B when exposed to visible or near infrared light (NIR) light. Among them, 20% -BYE/BO has the best photocatalytic activity, and its NIR-light degradation ratio of Ciprofloxacin is as high as 66 and 103 times that of BO and BYE, respectively. The enhanced photoactivity of as-synthesized BYE/BO heterojunction is attributed to synergistic effects of the upconversion and the direct Z heterojunction. Moreover, capture experiment showed that the·O 2 - and h + were main active species, and the directive Z-scheme mechanism was proposed. • BiOI:Yb 3+ ,Er 3+ /Bi 2 O 4 was successfully synthesized by a microwave-assisted hydrothermal method. • BiOI:Yb 3+ ,Er 3+ /Bi 2 O 4 shows enhanced photodegradation performance for RhB and CIP under visible/NIR light. • The upconversion effect extends the spectral range of light absorption. • Direct Z-scheme photocatalytic system promotes the separation efficiency of carriers.