We herein demonstrate self-doping of the CO 3 2− anionic group into a wide bandgap semiconductor Bi 2 O 2 CO 3 realized by a one-pot hydrothermal technique. The photoresponsive range of the self-doped Bi 2 O 2 CO 3 can be extended from UV to visible light and the band gap can be continuously tuned. Density functional theory (DFT) calculation results demonstrate that the foreign CO 3 2− ions are doped in the caves constructed by the four adjacent CO 3 2− ions and the CO 3 2− self-doping can effectively narrow the band gap of Bi 2 O 2 CO 3 by lowering the conduction band position and meanwhile generating impurity level. The photocatalytic performance is evaluated by monitoring NO removal from the gas phase, photodegradation of a colorless contaminant (bisphenol A, BPA) in an aqueous solution, and photocurrent generation. In comparison with the pristine Bi 2 O 2 CO 3 which is not sensitive to visible light, the self-doped Bi 2 O 2 CO 3 exhibits drastically enhanced visible-light photoreactivity, which is also superior to that of many other well-known photocatalysts such as P25, C 3 N 4 , and BiOBr. The highly enhanced photocatalytic performance is attributed to combination of both efficient visible light absorption and separation of photogenerated electron− hole pairs. The self-doped Bi 2 O 2 CO 3 also shows decent photochemical stability, which is of especial importance for its practical applications. This work demonstrates that self-doping with an anionic group enables the band gap engineering and the design of high-performance photocatalysts sensitive to visible light.
Herein we report the Bi 2 O 2 CO 3 single-crystal nanoplates with dominant {001} exposing facets fabricated via a controllable hydrothermal means. Exposed {001} reactive facets enable BOC-001 nanoplates efficient separation and migration of photoinduced electron−hole pairs, thereby resulting in highly enhanced photoreactivity pertaining to rhodamine B degradation, NO removal, and photocurrent generation. The present work provides a new reference for manipulation of facet-dependent photocatalytic activity of semiconductors. N owadays, semiconductor crystal-facet engineering is very active, which paves a new way for physicochemical property tailoring and the photoactivity enhancement of photocatalysts. 1−5 The successful synthesis of active {001} facets of anatase TiO 2 crystals via HF serving as a capping agent opened the door of research on facet-dependent photocatalytic performance. 6,7 Two-dimensional (2D) bismuth nanomaterials have also drawn considerable attention because their layered crystal configuration can afford an internal driving force promoting the effective separation of photoinduced charge carriers. 8−12 As a typical 2D layered photocatalyst, bismuth oxychloride (BiOCl) gains special interest for facet-controlled manufacture of its single crystal. BiOCl also exhibits facetdependent photocatalytic activity that strongly lies on the dominant exposing facets of the crystal. 13−17 It was disclosed that BiOCl single-crystalline nanosheets with exposed {001} facets enable more efficient separation of photoexcited electron−hole pairs, thus displaying higher photoreactivity than the counterpart with exposed {010} facets. 13 That is to say, the {001} facets are the highly reactive facets in BiOCl.Bismuth carbonate (Bi 2 O 2 CO 3 ), as a newcomer of the "silleń" family that is a kind of bismuth compound composed of [Bi 2 O 2 ] 2+ layers and interlaid halogen ions or anionic groups, also features a 2D layered crystal structure built by [Bi 2 O 2 ] 2+ layers and [CO 3 ] 2− triangles. 18 Lately, we found that Bi 2 O 2 CO 3 exhibits a large nonlinear optical (NLO) effect with strong second-harmonic generation (SHG), which results from its non-centrosymmetrical crystal structure and the aligned arrangement of the [CO 3 ] anionic group. 19 Nevertheless, the property of most concern for Bi 2 O 2 CO 3 is the high photocatalytic performance. 20−29 Zheng etc. first reported the synthesis and photocatalytic activity of Bi 2 O 2 CO 3 samples with different morphologies, 20 including a flower-like sample, sponge-like porous sphere sample, and plate-like sample. Among them, the flower-like Bi 2 O 2 CO 3 exhibits the highest rhodamine B degradation activity. On the basis of the HRTEM results, the flower-like Bi 2 O 2 CO 3 products are considered to be composed of {001}-plane exposed flakes. Thus, the high photocatalytic activity of flower-like Bi 2 O 2 CO 3 was thought to be mainly from the exposed reactive {001} plane of the flakes. Besides, the Bi 2 O 2 CO 3 -based composite photocatalysts also show high photoactivity; e...
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