Li-Hua Huo

Bio: Li-Hua Huo is an academic researcher from Heilongjiang University. The author has contributed to research in topics: Coordination polymer & Hydrogen bond. The author has an hindex of 17, co-authored 214 publications receiving 1529 citations.

A novel strategy for making soluble reduced graphene oxide sheets cheaply by adopting an endogenous reducing agent

Abstract: A facile and efficient strategy is described for the fabrication of soluble reduced graphene oxide (rGO) sheets. Different from the conventional strategies, the proposed method is based on the reduction of graphene oxide by an endogenous reducing agent from a most widely used and cost-effective solvent, without adding any other toxic reducing agent. Simultaneously, this solvent can serve as an effective stabilizer, avoiding complicated and time-consuming modification procedures. The as-prepared rGO sheets not only exhibit high reduction level and conductivity, but also can be well dispersed in many solvents. Of particular significance is that rGO sheets can be produced in large quantities. These advantages endow this proposed synthetic approach great potential applications in the construction of high-performance graphene-based devices at low cost, as demonstrated in our study of NO gas sensing.

Hydrothermal growth and gas sensing property of flower-shaped SnS2 nanostructures

Abstract: Unusual 3D flower-shaped SnS2 nanostructures have been synthesized using a mild hydrothermal treatment in the presence of octyl-phenol-ethoxylate (Triton X-100) at 160 °C. The nanostructures have an average size of 1 µm, and consist of interconnected nanosheets with thicknesses of about 40 nm. Based on time-dependent experimental results, we ascribe the oriented attachment mechanism to the growth of the SnS2 nanostructures. The nonionic surfactant Triton X-100 plays a key role in the formation of the flower-like morphology. Room temperature gas-sensing measurements show that the 3D SnS2 nanostructures could serve as sensor materials for the detection of NH3 molecules.

Alcohols and acetone sensing properties of SnO2 thin films deposited by dip-coating

Abstract: SnO2 thin films were prepared by dip-coating from SnO2 sols of 0.5 and 0.1 mol/l. The structure and morphology of the films were analyzed through XRD, UV and AFM methods. The particles in the films were the standard tetragonal phase of SnO2 with spherical morphology. The average size of SnO2 particles was about 87 nm (0.5 mol/l) and 5 nm (0.1 mol/l), respectively. The UV absorbance of the films increased linearly with increasing the deposition layers. The sensitivity of thin films to methanol, ethanol, propanol and acetone was detected at room temperature, and the effects of concentration of SnO2 sols on the morphology and sensitivity of the films were investigated as well. With decreasing the sol concentration, the grain size of the particles reduced, the gas sensing properties to acetone and ethanol increased. Such films with small size could detect ethanol as low as 2 ppm ethanol. Response and recovery time to methanol, ethanol, propanol and acetone at room temperature were within 30 s and 1 min, respectively.

Sol–gel route to pseudocubic shaped α-Fe2O3 alcohol sensor: preparation and characterization

Abstract: α-Fe 2 O 3 hydrosol was synthesized by sol–gel method with FeCl 3 ·6H 2 O as the raw material and its thin films were prepared by dip-coating technique. The structure, morphology and spectroscopy of the thin films were characterized by XRD, AFM, UV–vis and FT-IR analysis methods. The results showed that uniform α-Fe 2 O 3 monolayer and multilayers could be obtained at certain dip-coating speed. The particles were pseudocubic shaped, with the mean particle size of about 58 nm. The formation mechanism of α-Fe 2 O 3 particles was explored by IR spectra and the change of the system acidity and conductivity. The results indicated that α-Fe 2 O 3 particles formed from the intermediate complex β-FeOOH. The gas-sensing properties of the multilayers to alcohols with different chain length were measured at room temperature. The thin films exhibited high sensitivity and rapid response–recovery characteristics to these gases. The film can detect C 3 H 7 OH vapor concentration as low as 2 ppm. The response and recovery time of the film to CH 3 OH and C 2 H 5 OH vapor is within 20 and 50 s, respectively.

Rare-earth organic frameworks involving three types of architecture tuned by the lanthanide contraction effect: hydrothermal syntheses, structures and luminescence.

Abstract: The first example of rare-earth organic frameworks with 3-aminopyrazine-2-carboxylic acid (Hapca) was synthesized under hydrothermal conditions and characterized by elemental analysis, IR, PL, TG, powder and single-crystal X-ray diffraction. These ten complexes exhibit three different structure types with decreasing lanthanide radii: [La(apca)3]n (1) for type I, {[Ln(apca)(ox)(H2O)2]·H2O}n (Ln = Pr (2), Nd (3), ox = oxalate) for type II, and [Ln2(apca)4(OH)2(H2O)2]n (Ln = Sm (4), Eu (5), Gd (6), Tb (7), Dy (8), Er (9), Y (10)) for type III. The structure of type I consists of 1D “snowflake” chains along a-axis, which are further interconnected by hydrogen bonds to produce a 3D sra net topology containing infinite (–C–O–La–)n rod-shaped SBU. Type II has 2D Ln-apca-ox 44-net, in which a planar udud water tetramers (H2O)4 are formed by coordinated and free water molecules. Type III also comprises of 2D 44-layer network constructed from Ln-apca-OH. The structure diversity is mainly caused by the variation of coordinated ligand and lanthanide contraction effect. Remarkably, the oxalate in type II was in situ synthesized from 3-aminopyrazine-2-carboxylic acid through an oxidation-hydrolysis reaction. The luminescent investigations reveal that complex 1 exhibits strong blue emission and complex 5 exhibits characteristic luminescence of Eu3+.

Graphene-Based Materials: Synthesis, Characterization, Properties, and Applications

Abstract: Graphene, a two-dimensional, single-layer sheet of sp(2) hybridized carbon atoms, has attracted tremendous attention and research interest, owing to its exceptional physical properties, such as high electronic conductivity, good thermal stability, and excellent mechanical strength. Other forms of graphene-related materials, including graphene oxide, reduced graphene oxide, and exfoliated graphite, have been reliably produced in large scale. The promising properties together with the ease of processibility and functionalization make graphene-based materials ideal candidates for incorporation into a variety of functional materials. Importantly, graphene and its derivatives have been explored in a wide range of applications, such as electronic and photonic devices, clean energy, and sensors. In this review, after a general introduction to graphene and its derivatives, the synthesis, characterization, properties, and applications of graphene-based materials are discussed.

Strong two-photon-induced fluorescence from photostable, biocompatible nitrogen-doped graphene quantum dots for cellular and deep-tissue imaging.

Abstract: Bright two-photon fluorescent probes are highly desirable to be able to optically probe biological activities deep inside living organisms with larger imaging depth, minor autofluorescence background, and less photodamage. In this study, we report the biocompatible nitrogen-doped graphene quantum dots (N-GQDs) as efficient two-photon fluorescent probes for cellular and deep-tissue imaging. The N-GQD was prepared by a facile solvothermal method using dimethylformamide as a solvent and nitrogen source. The two-photon absorption cross-section of N-GQD reaches 48 000 Goppert-Mayer units, which far surpasses that of the organic dyes and is comparable to that of the high performance semiconductor QDs, achieving the highest value ever reported for carbon-based nanomaterials. More importantly, a study of penetration depth in tissue phantom demonstrates that the N-GQD can achieve a large imaging depth of 1800 μm, significantly extending the fundamental two-photon imaging depth limit. In addition, the N-GQD is nont...