A facile and environment friendly approach to synthesis of unique hierarchical BiOCl flowery microspheres(FMs)using a biodegradable surfactant polyvinyl alcohol(PVA)was reported herein for the first time.Compared to the BiOCl nanosheets synthesized in the absence of PVA,hierarchical BiOCl FMs consist of large amounts of interwoven polycrystalline nanosheets that assemble into a porous flowery structure.The formation mechanism of the hierarchical BiOCl FMs was also proposed,whereby PVA was believed to play a key role in the crystal growth and the formation of the final microstructures.Compared with TiO2-P25 and BiOCl nanosheets,hierarchical BiOCl FMs displayed remarkably enhanced photocatalytic activity,and20 mg of BiOCl FMs could completely degrade 50 mL of methyl orange solution(20 mg/L)within 30 min under UVlight irradiation.According to the comprehensive analysis,it can be concluded that the larger specific surface area,porosity,suitable band gap,and the enhanced light absorption capacity may contribute to the remarkably enhanced photocatalytic activity.This facile and green approach to fabricating hierarchical BiOCl FMs would give vital clues to develop new route for synthesizing other hierarchical structured materials.
A novel glucose biosensor based on graphene nanosheets(GNs)modified gold nanowire arrays(AuNWAs)electrode was constructed.Highly ordered gold nanowire arrays were prepared by direct electrodeposition in anodic aluminum oxide templates.GNs were synthesized through a public route involving graphite oxidation,exfoliation,and chemical reduction.Field emission scanning electron microscope and high-resolution transmission electron microscope were employed to characterize the asprepared AuNWAs and GNs.Glucose oxidase was immobilized on the surface of GNs-AuNWAs modified electrode via a cross-linking method.The cyclic voltammetry results showed that the GNs-AuNWAs-based glucose biosensors have high catalysis activity to hydrogen peroxide(H2O2)than those modified with GNs or AuNWAs only.Furthermore,amperometric response was employed to detect glucose concentration owing to its simplicity,high selectivity,and relative low cost.Glucose biosensors based on GNs-AuNWAs showed excellent performance with high sensitivity of 40.25 lA cm-2(mmol/L)-1,low detection limit of 0.02 mmol/L,and a linear range from 0.02 to 3 mmol/L.
An activation process for developing the surface and porous structure of palygorskite/carbon(PG/C) nanocomposite using ZnC l2 as activating agent was investigated. The obtained activated PG/C was characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), field-emission scanning electron microscopy(SEM), and Brunauer–Emmett–Teller analysis(BET) techniques. The effects of activation conditions were examined,including activation temperature and impregnation ratio. With increased temperature and impregnation ratio, the collapse of the palygorskite crystal structure was found to accelerate and the carbon coated on the surface underwent further carbonization. XRD and SEM data confirmed that the palygorskite structure was destroyed and the carbon structure was developed during activation. The presence of the characteristic absorption peaks of C_C and C–H vibrations in the FTIR spectra suggested the occurrence of aromatization. The BET surface area improved by more than 11-fold(1201 m2/g for activated PG/C vs. 106 m2/g for PG/C) after activation, and the material appeared to be mainly microporous. The maximum adsorption capacity of methylene blue onto the activated PG/C reached 351 mg/g. The activated PG/C demonstrated better compressive strength than activated carbon without palygorskite clay.
