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Single-crystalline bismuth titanates (Bi 12 TiO 20 ) with the cubic phase and various morphologies (flower-, belt-, tetrahedral-like) were controllably fabricated by using a mild template-free hydrothermal process.The samples were fully characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM, nitrogen porosimetry measurement, UV-vis diffuse reflectance spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS).The influence of the solvent and the concentration of NO 3 2 in the reaction system on the crystallinity and morphology of the Bi 12 TiO 20 samples was investigated in detail. Bi 12 TiO 20 crystals were used as the sunlight-driven photocatalysts to degrade aqueous dye methyl orange (MO) and p-nitrophenol (PNP), and the influence of Bi 12 TiO 20 morphology on the photocatalytic activity was discussed. Finally, the recyclability of Bi 12 TiO 20 was evaluated through three consecutive runs.

Two In-based metal−organic frameworks (MOFs) have been designed and synthesized by the reaction of 3phenylpyridine polycarboxylic ligands and In 3+ cations: In 3 L 1 4 •(CH 3 NH 2 CH 3 ) 3 (H 3 L 1 = 5-(3′,5′-dicarboxylphenyl)nicotic acid; 1) and In 2 L 2 2 (CH 3 COO) 2 •(CH 3 ) 2 NH 2 •(CH 3 ) 3 NH•H 2 O (H 3 L 2 = 3-(2,4-dicarboxylphenyl)-6-carboxylpyridine;2). Singlecrystal X-ray diffraction analysis indicates that the In 3+ centers in 1 are all coordinated by eight oxygen atoms from four carboxylate groups, resulting in a 3D framework with two different channels A and B with sizes of 14.4 × 8.75 and 7.24 × 6.7 Å 2 , respectively. In 2, each In 3+ center was coordinated by six carboxylate oxygen atoms and a pyridine N atom, forming a 2D layerlike structure. These 2D layers are further fused together via electrostatic interactions into a 3D supramolecular framework, showing two kinds of channels A′ and B′ with pore sizes of 5.25 × 9.69 and 4.29 × 8.66 Å 2 , respectively. In this work, the coordination of N to the In 3+ center in 2 was first achieved by regulating carboxyl sites in 3-phenylpyridine, thus increasing the stability of the In-based MOF. A detailed structural study reveals that the formation of In−N bonds promotes the conversion of the 3D framework of 1 into the supramolecular structure of 2. However, the supramolecular structure in 2 is more stable in air and methanol in comparison to the 3D framework of 1, confirming the important role of In−N bonds in enhancing the framework stability. Thus, 2 could be used as a stable adsorbent to selectively capture CO 2 from a CO 2 /N 2 mixture, while 1 broke down sharply in air and in a methanol solution.

For the first time, ordered mesoporous ZnO nanoparticles have been synthesized by a template method. The electroplating after chemical plating method was creatively used to form copper film on the surface of the prepared ZnO, and then a CuO film-decorated ordered porous ZnO composite (CuO/ZnO) was obtained by a high-temperature oxidation method. In2O3 was loaded into the prepared CuO film–ZnO by an ultrasonic-assisted method to sensitize the room temperature gas-sensing performance of the prepared CuO/ZnO materials. The doped In2O3 could effectively improve the gas-sensing properties of the prepared materials to nitrogen oxides (NOx) at room temperature. The 1% In2O3 doped CuO/ZnO sample (1 wt% In2O3–CuO/ZnO) showed the best gas-sensing properties whose response to 100 ppm NOx reached 82%, and the detectable minimum concentration reached 1 ppm at room temperature. The prepared materials had a good selectivity, better response, very low detection limit, and high sensitivity to NOx gas at room temperature, which would have a great development space in the gas sensor field and a great research value.