title: Mesoporous layer-by-layer ordered nanohybrids of layered double hydroxide and layered metal oxide: highly active visible light photocatalysts with improved chemical stability.
abstract: Mesoporous layer-by-layer ordered nanohybrids highly active for visible light-induced O(2) generation are synthesized by self-assembly between oppositely charged 2D nanosheets of Zn-Cr-layered double hydroxide (Zn-Cr-LDH) and layered titanium oxide. The layer-by-layer ordering of two kinds of 2D nanosheets is evidenced by powder X-ray diffraction and cross-sectional high resolution-transmission electron microscopy. Upon the interstratification process, the original in-plane atomic arrangements and electronic structures of the component nanosheets remain intact. The obtained heterolayered nanohybrids show a strong absorption of visible light and a remarkably depressed photoluminescence signal, indicating an effective electronic coupling between the two component nanosheets. The self-assembly between 2D inorganic nanosheets leads to the formation of highly porous stacking structure, whose porosity is controllable by changing the ratio of layered titanate/Zn-Cr-LDH. The resultant heterolayered nanohybrids are fairly active for visible light-induced O(2) generation with a rate of ∼1.18 mmol h(-1) g(-1), which is higher than the O(2) production rate (∼0.67 mmol h(-1) g(-1)) by the pristine Zn-Cr-LDH material, that is, one of the most effective visible light photocatalysts for O(2) production, under the same experimental condition. This result highlights an excellent functionality of the Zn-Cr-LDH-layered titanate nanohybrids as efficient visible light active photocatalysts. Of prime interest is that the chemical stability of the Zn-Cr-LDH is significantly improved upon the hybridization, a result of the protection of the LDH lattice by highly stable titanate layer. The present findings clearly demonstrate that the layer-by-layer-ordered assembly between inorganic 2D nanosheets is quite effective not only in improving the photocatalytic activity of the component semiconductors but also in synthesizing novel porous LDH-based hybrid materials with improved chemical stability.
authors.affiliation: Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul, Korea.
authors.forename: Jayavant L
authors.initials: JL
authors.lastname: Gunjakar
authors.forename: Tae Woo
authors.initials: TW
authors.lastname: Kim
authors.forename: Hyo Na
authors.initials: HN
authors.lastname: Kim
authors.forename: In Young
authors.initials: IY
authors.lastname: Kim
authors.forename: Seong-Ju
authors.initials: SJ
authors.lastname: Hwang
mesh_terms: D002384:Catalysis; D002857:Chromium / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry*; D008027:Light; D049449:Luminescence; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology; D010087:Oxides / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010316:Particle Size; D055668:Photochemical Processes; D016062:Porosity; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D008567:Membranes, Artificial; D010087:Oxides; D002857:Chromium; C031356:hydroxide ion; D014025:Titanium; D015032:Zinc; D010100:Oxygen