BiOI/Bi2O2CO3 Two-Dimensional Heteronanostructures with Boosting Charge Carrier Separation Behavior and Enhanced Visible-Light Photocatalytic Performance

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, +infinity, 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.