Honghui Yang

Enhanced bio-hydrogen production from corncob by a two-step process: dark- and photo-fermentation.

Enhanced bio-hydrogen production from pretreated corncob by integrating dark-fermentation with photo-fermentation process was investigated in this study. In the first step, the maximum bio-hydrogen yield and rate from corncob by dark-fermentation was 120.3+/-5.2 mL H(2)/g-corncob and 150 mL H(2)/(Lh), respectively. In the second step, a hydrogen yield of 713.6+/-44.1 mL H(2)/g-COD was obtained from digesting the effluent of dark-fermentation by photosynthetic bacteria. Meanwhile, COD removal efficiency achieved 90%. Bio-hydrogen production in the first step was mainly attributed to the bioconversion of the reducing sugars and oligosaccharides in the hydrolyzate of corncob. Bio-hydrogen production in the second step was due to the biodegradation of acetic acid, butyric acid, butyl alcohol and ethanol in the effluent of dark-fermentation.

Fabrication of one-dimensional heterostructured TiO2@SnO2 with enhanced photocatalytic activity

TiO2@SnO2 nanosheets@nanotubes heterostructures were successfully prepared by a facile two-step method: prefabricated SnO2@PNT coaxial nanocables based on the in situ growth of SnO2 in the sulfonated gel matrix of polymeric nanotubes, and then the assembly of TiO2 nanoclusters that consist of ultrathin nanosheets through a solvothermal process. These heterostructures were characterized for the morphological, structural and optical properties by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) and diffuse reflectance spectroscopy (DRS). The photocatalytic investigations showed that the TiO2@SnO2 heterostructures possessed enhanced photocatalytic efficiency in the photodegradation of Rhodamine B (RhB) and photocatalytic H2 evolution from water splitting under ultraviolet (UV) light irradiation, compared with the pristine TiO2 nanosheets, SnO2 nanotubes, the mechanically mixed two samples and P25. The enhanced photocatalytic performance can be ascribed to the beneficial microstructure and synergistic effects of coupled TiO2@SnO2 nanosheets@nanotubes heterostructures.

Fabrication and formation mechanism of Mn2O3 hollow nanofibers by single-spinneret electrospinning

Mn2O3 hollow nanofibers (Mn2O3 HNs) have been prepared by direct annealing of electrospun polyvinylpyrrolidone (PVP)/manganese acetate composite nanofibers. The morphology, crystal structure and compositions of the Mn2O3 HNs were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The results indicated that composite nanofibers after calcination at high temperature still retain their fibrous morphology with a fascinating hollow structure. The resultant HNs are Mn2O3 of high purity. The temperature-dependent experiments were carried out to monitor the evolution process of Mn2O3 HNs. The well-defined Mn2O3 HNs are the products of the reversed crystallization during the annealing process.

Enhanced photo-fermentative hydrogen production by Rhodobacter capsulatus with pigment content manipulation

High content of pigment in purple nonsulfur photosynthetic bacteria hinders its photo-hydrogen production rate under intense light irradiation. In order to alleviate the light shielding effect and improve its photo-fermentative hydrogen production performance, pufQ, which is the regulatory gene of bacteriochlorophyll biosynthesis in Rhodobacter capsulatus, was cloned and relocated in the genome under cbb3 promoter by homologous recombination. The UV-vis spectra indicated that the light absorption of the mutant between 300 and 900 nm was reduced. Photo-hydrogen production experiments by the recombinant and wild type strain were carried out in 350 mL photo bioreactors using acetic and butyric acid as substrate. The results showed that the hydrogen production of recombinant with reduced pigment was 27% higher than that of its parental strain, indicating that it is effective on enhancing photo-fermentative hydrogen production by manipulating pigment biosynthesis in purple nonsulfur photosynthetic bacteria.

Effect of ethanol on the crystallinity and acid sites of MFI zeolite nanosheets

A series of MFI zeolite nanosheets were synthesized using hydrothermal method with ammonium surfactant (C22-6-6) as the zeolite structure-generating agent. The effects of ethanol concentration on the textural properties, crystal morphology and acidic properties of the zeolite samples were studied. The zeolite samples were characterized by X-ray powder diffraction, N2 adsorption isotherms and scanning electron micrographs of the porous materials. The results showed that the addition of ethanol promoted the crystallization of zeolite, and a large number of crystals grew along the b-axis orientation. Based on NH3-TPD and pyridine-adsorbed FT-IR results, the increase of crystallinity enhanced the acidic properties of the prepared samples. It was attributed to the fact that more aluminum atoms in the sample with higher crystallinity entered into the zeolites framework structure, and participated in coordination. These aluminum atoms coordinating to the oxygen atoms in the framework created Lewis acid and Bronsted acid sites. The present study indicated that ethanol could function as cosolvent and a secondary template to tailor the textural and acidic properties of MFI nanosheets assemblies primarily guided by C22-6-6 templates. In addition, the quantification of acid site accessibility demonstrated the improvement of the available acid sites and the bulky molecular diffusion efficiency in the MFI nanosheets zeolite.

Fabrication and photocatalytic activities of SrTiO 3 nanofibers by sol–gel assisted electrospinning

Abstract SrTiO3 nanofibers were successfully prepared by a facile electrospinning method with subsequent calcination in air. These one dimensional nanostructures were characterized for the morphological, structural and optical properties by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–visible diffuse reflectance spectroscopy. The photocatalytic investigations showed that the SrTiO3 nanofibers possessed enhanced photocatalytic efficiency in photodegradation of rhodamine B and photocatalytic H2 evolution from water splitting under ultraviolet light irradiation, compared with the SrTiO3 nanoparticles and P25. The enhanced photocatalytic performance can be ascribed to the beneficial microstructure and more negative conduction band edge compared with P25.

Enhanced capacitance of rectangular-sectioned polypyrrole microtubes as the electrode material for supercapacitors

Rectangular-sectioned polypyrrole microtubes (R-PPy) were synthesized in aqueous solution with β-cyclodextrin (β-CD)/I2 inclusion compound and FeCl3 by chemical oxidation. Field emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were used to characterize the formation and molecular structure of R-PPy. From the results of the characterization, Complexes of β-CD/I2–Fe2+ acted as the soft-template during the synthesis process of rectangular-sectioned polypyrrole microtubes. Some I− ions retained in the backbone of the as-prepared PPy served as the counter ions after rinsing. Furthermore, R-PPy demonstrated higher conductivity and better electrochemical properties than PPy particles synthesized by the conventional method (C-PPy). The specific capacitance of R-PPy (322.5 F g−1 at the current of 1 A g−1) is almost twice as large as that of C-PPy. The original specific capacitance of R-PPy can be maintained at around 83.3% whereas it was only about 61.5% for the C-PPy after 2000 charge–discharge cycles. The larger specific capacitance and relatively high cycling stability of R-PPy make it a more attractive candidate for energy storage electrodes than C-PPy.

Application of chemically synthesized polypyrrole with hydro-sponge characteristic as electrode in water desalination†

In this article, the chemical oxidative approach was employed to synthesize bulk sponge-like polypyrrole; p-toluenesulfonate (pTSNa), sodium benzene-sulfonate (BSNa) and sodium nitrate (NaNO3) were chosen, respectively, as doping agents to modify the sponge polypyrrole. The microstructure, specific surface area and electrochemical activity of doped polypyrrole samples were characterized. Through repeated expansion and contraction tests, it was proved that the bulk polypyrrole samples exhibited excellent sponge property. To investigate the potential desalination ability, this type of sponge-characteristic polypyrrole was processed into electrodes, and applied in saline solution to remove sodium ions by the electrochemical approach. The results showed that the sponge polypyrrole performed wonderful desalination effect with above 20 mg Na+ for per gram polypyrrole.

Fabrication of novel perovskite-type Sr2Ta(Fe1−xGax)O6 nanoparticles with high visible-light photocatalytic activity

Novel Sr2Ta(Fe1−xGax)O6 perovskite photocatalysts were successfully synthesized by a simple one-step sol–gel method and characterized for structural, morphological and optical properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), Brunauer Emmett Teller (BET) and UV-visible (UV-vis) diffused reflectance spectroscopy (DRS), respectively. A sample of Sr2Ta(Fe0.8Ga0.2)O6 calcined at 900 °C for 10 h exhibited the highest photocatalytic activity, and the photodegradation rate of methylene blue (MB) achieved 96.2% after 2 h visible light irradiation. The enhanced photocatalytic performance and outstanding stability were attributed to the appropriate crystallinity, Ga3+ doping content and the special perovskite structure. This Ga-doping created impurity levels in the forbidden band, which shortened the band gap and generated more photoactive sites to facilitate photocatalytic activity.

Tow steps biohydrogen production: biomass pretreatment and fermentation

This paper investigated the pretreatment of cornstalk and integrated dark‐photo fermentation for hydrogen production. Five parameters of the pretreatment experiments, including NaOH concentration, temperature, residence time, and dosage of cellulase and xylanase, were optimized through the L25 (5≙5) orthogonal test. The optimal NaOH concentration, temperature, residence time, and dosage of cellulase and xylanase were 0.5wt%, 115 °C, 3 h, 0.08g/g cornstalk, 0.08g/g cornstalk, respectively. Under the optimal conditions, 0.31g glucose/g cornstalk was obtained. The two‐step fermentation consisted of dark fermentation and photo fermentation. The pretreated cornstalk was used as the substrate for dark fermentation, with cow dung as the inoculum. Then the effluents of dark fermentation were employed as the substrate for photo fermentation by photosynthetic bacteria. H2 yield of dark fermentation was 116.7 mL/g cornstalk, with H2 concentration of 41%. After photo fermentation, the total H2 yield increased to 294 ...