Xianchun Liu

In situ loading of Ag2WO4 on ultrathin g-C3N4 nanosheets with highly enhanced photocatalytic performance.

The g-C3N4 nanosheets (g-C3N4NS) exhibit more excellent property than common bulk g-C3N4 (g-C3N4-B) due to their large surface areas, improved electron transport ability and well dispersion in water. In this work, ultrathin g-C3N4NS with a thickness of about 2.7nm have been synthesized by a simple thermal exfoliation of bulk g-C3N4, and then Ag2WO4 nanoparticles are in situ loaded on their surface to construct the Ag2WO4/g-C3N4NS heterostructured photocatalysts. Due to their unique physicochemical properties, the as-prepared heterostructures possess a fast interfacial charge transfer and increased lifetime of photo-excited charge carriers, and exhibit much higher photocatalytic activity. Under visible light irradiation, the optimum photocatalytic activity of Ag2WO4/g-C3N4NS composites is almost 53.6 and 26.5 times higher than that of pure g-C3N4-B and Ag2WO4/g-C3N4-B heterostructures towards the degradation of rhodamine B, respectively, and is almost 30.6 and 9.8 times higher towards the degradation of methyl orange, respectively. In addition, the natural sunlight photocatalytic activities of the as-prepared samples are also investigated.

Chirality and magnetism of an open-framework cobalt phosphite containing helical channels from achiral materials

A new chiral open-framework cobalt phosphite [C6N2H14][Co(HPO3)2] (1) with helical channels has been synthesized under solvothermal conditions in the presence of achiral organic amine. The circular dichroism (CD) spectrum indicates that the bulk crystals have optical activity. Magnetic measurements reveal that 1 is a weak ferromagnet.

Surfactant-assisted hydrothermal synthesis and electrochemical properties of nanoplate-assembled 3D flower-like Cu3V2O7(OH)2·2H2O microstructures

Micrometer-scale hierarchical flower-like structures of Cu3V2O7(OH)2·2H2O assembled by nanoplates were, for the first time, fabricated in a high yield via a simple hydrothermal process in the presence of cetyltrimethylammonium bromide (CTAB). X-Ray diffraction, Fourier-transform infrared spectroscopy (FTIR) spectrum, scanning electron microscopy and transmission electron microscopy were used to characterize the samples. The results demonstrated that CTAB played an important role as a soft template in the formation of the 3D Cu3V2O7(OH)2·2H2O architecture. The formation mechanism was preliminarily studied based on XRD studies and SEM observations by arresting the growth at a series of intermediate stages in the formation of the flower-like structures. Some factors influencing the morphologies of the Cu3V2O7(OH)2·2H2O flower-like micro/nanocomposite structures were systematically investigated. The electrochemical measurements revealed that the Cu3V2O7(OH)2·2H2O microflowers displayed a high discharge capacity.

CaF2 and CaF2:Ln3+ (Ln = Er, Nd, Yb) hierarchical nanoflowers: hydrothermal synthesis and luminescent properties

Highly uniform three-dimensional flower-like CaF2 and CaF2:Ln3+ (Ln = Er, Nd, Yb) nanostructures have been successfully prepared by a facile hydrothermal method assisted by a chelating reagent, ethylenediamine tetraacetic acid disodium salt (Na2EDTA). The nanoflowers with size about 550 nm are assembled by numerous nanoflakes with a thickness of 10 nm. X-Ray diffraction, scanning electron microscopy, transmission electron microscopy, electron diffraction and photoluminescence spectra were used to characterize these materials. The formation process of the hierarchical CaF2 nanoflowers has been investigated in detail. It is found that reaction time and chelating reagent play a key role in forming the hierarchical nanoflowers. Furthermore, the near-infrared luminescence of lanthanide ion (Er, Nd, and Yb) doped CaF2 nanostructures, especially in the 1300–1600 nm region, is discussed and is of particular interest for telecommunications applications.

Preparation of Carbon‐Rich g‐C3N4 Nanosheets with Enhanced Visible Light Utilization for Efficient Photocatalytic Hydrogen Production

Exfoliation of layered bulk g-C3 N4 (CNB) to thin g-C3 N4 sheets in nanodomains has attracted much attention in photocatalysis because of the intriguing properties of nanoscaled g-C3 N4 . This study shows that carbon-rich g-C3 N4 nanosheets (CNSC) can be easily prepared by self-modification of polymeric melon units through successively thermally treating bulk g-C3 N4 in an air and N2 atmosphere. The prepared CNSC not only retain the outstanding properties of nanosheets, such as large surface area, high aspect ratios, and short charges diffusion distance, but also overcome the drawback of enlarged bandgap caused by the quantum size effect, resulting in an enhanced utilization of visible light and photoinduced electron delocalization ability. Therefore, the as-prepared CNSC show a high hydrogen evolution rate of 39.6 µmol h-1 with a turnover number of 24.98 in 1 h at λ > 400 nm. Under irradiation by longer wavelength of light (λ > 420 nm), CNSC still exhibit a superior hydrogen evolution rate, which is 72.9 and 5.4 times higher than that of bulk g-C3 N4 and g-C3 N4 nanosheets, respectively.

Sandwich-structured graphene-nickel silicate-nickel ternary composites as superior anode materials for lithium-ion batteries.

We report the synthesis of sandwich-structured graphene-nickel silicate-Ni ternary composites by using the solvothermal method followed by a simple in situ reduction procedure. The composites show an interesting structure with graphene sandwiched between two layers of well-dispersed Ni nanoparticles (NPs) anchored on ultrathin nickel silicate nanosheets. These ternary composites exhibit enhanced performance as anode materials owing to the synergistic effect between the graphene matrix and electrochemically inert Ni nanoparticles, an effect that holds promise for the design and fabrication of other advanced electrode materials.

Redox-active polyoxometalate-based crystalline material-immobilized noble metal nanoparticles: spontaneous reduction and synergistic catalytic activity

A 3D eight-connected redox-active polyoxometalate (POM)-based crystalline material, IFMC-101, has been synthesized based on reduced {P4Mo6O31H6}-based tetrameric clusters. IFMC-101 was used as a reducing agent and stabilizer to prepare Au and Pt nanoparticles (NPs) by auto-redox reactions without extra reduction assistance. For the first time, we have demonstrated a new strategy to prepare noble metal NP-loaded POM-based crystalline catalysts. These crystalline catalysts were employed toward the reduction of 4-nitrophenol by NaBH4 and the efficiency of the Au NP-loaded material, Au@IFMC-101, was nearly 9 times higher than that of the POM-based crystalline material, IFMC-101. This result reveals that Au@IFMC-101 exhibits enhanced activity owing to the synergistic catalysis of noble metal NPs and crystalline POM components.

A General Route to Hollow Mesoporous Rare‐Earth Silicate Nanospheres as a Catalyst Support

Hollow mesoporous structures have recently aroused intense research interest owing to their unique structural features. Herein, an effective and precisely controlled synthesis of hollow rare-earth silicate spheres with mesoporous shells is reported for the first time, produced by a simple hydrothermal method, using silica spheres as the silica precursors. The as-prepared hollow rare-earth silicate spheres have large specific surface area, high pore volume, and controllable structure parameters. The results demonstrate that the selection of the chelating reagent plays critical roles in forming the hollow mesoporous structures. In addition, a simple and low-energy-consuming approach to synthesize highly stable and dispersive gold nanoparticle-yttrium silicate (AuNPs/YSiO) hollow nanocomposites has also been developed. The reduction of 4-nitrophenol with AuNPs/YSiO hollow nanocomposites as the catalyst has clearly demonstrated that the hollow rare-earth silicate spheres are good carriers for Au nanoparticles. This strategy can be extended as a general approach to prepare multifunctional yolk-shell structures with diverse compositions and morphologies simply by replacing silica spheres with silica-coated nanocomposites.

Achieving MnO2 Nanosheets through Surface Redox Reaction on Nickel Nanochains for Catalysis and Energy Storage

The redox reaction between KMnO4 and Ni was carried out on a chain-like Ni surface under hydrothermal conditions and γ-MnO2 nanosheets were produced through this facile route. The original Ni nanochains, as cores, dominated the final morphology of the composites with MnO2 nanosheets loaded on their surface. The uniform assemblies of MnO2 , with large amounts of exposed sites, allowed them to be good candidates for application in various fields. The reduction of 4-nitrophenol by NaBH4 was selected as model reaction to test the catalytic activity of the samples and the samples could also be made into electrodes for supercapacitor measurement. Both the results revealed the advantages of the γ-MnO2 assembled on the Ni chain surfaces. Furthermore, the magnetic cores facilitated the recycling of the sample and increased the stability upon charge-discharge cycles.

Solvothermal synthesis and magnetic properties of cobalt(II) phosphite structures of varying dimensionality

Three new organically templated cobalt phosphites, [C4N2H12][Co(HPO3)2] (1), [(C4N2H12)0.5(C2NH8)][Co2(HPO3)3] (2) and [C2NH8]2[Co3(HPO3)4] (3) have been synthesized under solvothermal conditions templated by piperazine. Single-crystal structure analysis reveals that compound 1 displays a one-dimensional (1D) chain-like structure, containing corner-shared four-membered rings. In compound 2, the linkages between CoO4 and HPO3 units form an inorganic layer with 4- and 12-membered aperture, while in compound 3, corner-sharing CoO4 and HPO3 units give rise to a three-dimensional structure with 16-membered ring channels, in which organic amine cations reside. The presence of 4-membered rings and one-dimensional chain/ladder structures in all compounds shows that such units are vital for building up of higher dimensionality. The magnetic properties of the three compounds are also discussed.