It is vital for environment purification to design and prepare an artificial photocatalyst that can effectively separate photogenerated carriers and maintain the redox ability of system. In this paper, a g-C 3 N 4 /BiOI/Bi 2 O 2 CO 3 photocatalyst was rationally designed and successfully prepared via two-step in-situ transforming process. The results of X-ray diffraction, Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, and transmission electron microscopy confirm the successful synthesis of ternary g-C 3 N 4 /BiOI/Bi 2 O 2 CO 3 catalysts. The photocatalytic activities of all catalysts were assessed by the degradation of Rhodamine B (RhB) under simulated sunlight illumination. The g-C 3 N 4 /BiOI/Bi 2 O 2 CO 3 catalysts showed much higher photocatalytic activities than single g-C 3 N 4 , or BiOI and dual g-C 3 N 4 /BiOI. The results of electron spin resonance and active species trapping experiments revealed that h + and • O 2 − were responsible for the photodegradation of RhB, and a possible photogenerated carrier transport mechanism was proposed.
The BiOI/Bi 2 O 2 CO 3 p–n junctions were constructed by anion exchange method with Bi 2 O 2 CO 3 in situ growth on BiOI. Then, the surfaces of BiOI/Bi 2 O 2 CO 3 samples were modified by negative charge with (3-aminopropyl) triethoxysilane (APTES) in an ethanol solution. Finally, the ami-BiOI/Bi 2 O 2 CO 3 /graphene (RGO) ternary composites were fabricates by the simple hydrothermal reaction. The obtained photocatalysts were well characterized with the various characterization techniques to study their morphological, physical, optical, and photocurrent properties, and have been evaluated by investigating the degradation of Rhodamine B and tetracycline under visible irradiation. Compared with single BiOI, the BiOI/Bi 2 O 2 CO 3 photocatalysts displays higher photocatalytic activity, due to the formation of the electric fields between p–n heterojunction to promote the migration of photogenerated carriers. Moreover, the ami-BiOI/Bi 2 O 2 CO 3 /RGO composites with the best photocatalytic activities can be attributed to that the positively charged ami-BiOI/Bi 2 O 2 CO 3 were coupled with the negatively charged graphite oxide (GO) by electrostatically attraction to form the effectively interfacial contacts, causing the photocatalytic reaction sites increased, the range of light response expanded, the separation of photogenerated charge further improved. This work provides a feasible strategy for the construction of high efficiency semiconductor and RGO nanocomposite photocatalyst.
Tiantian Zhou,Haonan Zhang,Xin Zhang,Wensheng Yang,Yongqiang Cao,Ping Yang
BiOI/Bi2O2CO3 two-dimensional (2D) heteronanostructures (HNSs) have been crafted by the simple but effective ion-exchange technique in this work. Besides the routine advantages of pristine 2D materials, including the more surface-reactive sites, larger surface area, and short distance for the carriers to transfer from the material interior to the surface, the larger heterointerface of BiOI/Bi2O2CO3 2D HNSs could further promote the separation of photoinduced electron–hole pairs because of the built-in electric field in the junction, giving rise to their ultrahigh activities compared to the pristine and conventional composite samples. The in situ growth model of 2D HNSs via ion exchange endowed the HNSs with decreased distance of interfacial carrier transfer and energy barrier, together with superhigh structure stability, which was also beneficial to charge separation. The highest apparent rate constants of BiOI/Bi2O2CO3 2D HNSs for visible-light degradation of RhB can reach up to 4.4, 5.3, and 2.8 times (5.1, +∞, and 4.7 times for salicylic acid (SA)) those of pure BiOI, Bi2O2CO3, and conventional BiOI/Bi2O2CO3 complex photocatalysts, respectively. This enhanced charge carrier separation behavior was detailedly born out by the characterizations of photocurrent density, electrochemical impedance, and steady-state and time-resolved photoluminescence, along with selective photo-oxidation/-reduction depositions of metallic oxide and noble metals. Hopefully, BiOI/Bi2O2CO3 2D HNSs can also be applied to photosynthesis, solar cells as well as electrocatalysis and provide a paradigm for exploration in other two-dimensional HNS nanomaterials.
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