TiO2 nanoparticle-coated granular activated carbon (GAC) composite photocatalysts (CPs) were suc-cessfully prepared by a molecular adsorption-deposition (MAD) method. The CPs were detected by scanning electron microsc...TiO2 nanoparticle-coated granular activated carbon (GAC) composite photocatalysts (CPs) were suc-cessfully prepared by a molecular adsorption-deposition (MAD) method. The CPs were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), BET surface area and UV-Vis adsorption spectroscopy, and their photoactivity was evaluated by methyl orange (MO) photodegradation. The results show that small-sized TiO2 nanoparticles were dispersed well, deposited on the surface of GAC, and showed slight blue shift in comparison with pure TiO2. With the increase in TiO2 content, the CPs showed band gaps in lower energy, smaller surface areas and the higher content of Ti3+ ions. Compared with pure TiO2 and others CPs samples, CPs-382 sample showed the highest photoactivity due to the optimum TiO2 content and surface area besides the synergic effect of photocatalytic degradation of TiO2 and adsorptive property of GAC. In addition, the CPs could be very easily reclaimed, recycled and reused for methyl orange removal while high photoactivity is pre-served.展开更多
Carbon dots(CDs)have gained unprecedented attention as a novel luminescent zero-dimensional carbon nanomaterial owing to their diverse industrial applications.Herein,we reported the sus-tainable synthesis of fluoresce...Carbon dots(CDs)have gained unprecedented attention as a novel luminescent zero-dimensional carbon nanomaterial owing to their diverse industrial applications.Herein,we reported the sus-tainable synthesis of fluorescent CDs from papaya peel waste,acting as a natural carbon orig-inator.As-prepared CDs and reduced graphene oxide(RGO)were fabricated in the composites through a facile one-step hydrothermal method.Synthesized RGO/CDs(RC)nanocomposites were characterized using spectroscopic,diffraction,and electron-microscopic techniques.Nanocom-posites with variable RGO to CD mass ratios were tested for photodegradation of textile dye methylene blue(MB).The highest photocatalytic activity(degradation efficiency of 87%in 135 min)was obtained in the nanocomposite containing a 2꞉1 mass ratio(RC2).The RGO sheets in the nanocomposite acted as media for electron acceptors,promoting the fast transfer and sep-aration of photoinduced electrons during CDs excitation,thus preventing the recombination of the electron and holes.Based on the agar well diffusion assay,the nanocomposites exhibited ex-cellent antibacterial activity than other tested materials against Bacillus subtilis(Gram-positive)and Pseudomonas aeruginosa(Gram-negative)bacterium.The largest inhibition zone area(22 mm),i.e.,the highest antimicrobial activity,was obtained in the nanocomposite tested against Gram-positive strains.Taken together,the synergistic effect of RGO and CDs enhanced the pho-tocatalytic and antibacterial performance of synthesized nanocomposite material.展开更多
基金the Natural Science Foundation of Hunan Province (Grant No.06JJ50150)the Scientific Research Fund of Science and Technology Department of Hunan Province (Grant No.2007GK3060)Jishou University (Grant No.JSDXKYZZ200648)
文摘TiO2 nanoparticle-coated granular activated carbon (GAC) composite photocatalysts (CPs) were suc-cessfully prepared by a molecular adsorption-deposition (MAD) method. The CPs were detected by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), BET surface area and UV-Vis adsorption spectroscopy, and their photoactivity was evaluated by methyl orange (MO) photodegradation. The results show that small-sized TiO2 nanoparticles were dispersed well, deposited on the surface of GAC, and showed slight blue shift in comparison with pure TiO2. With the increase in TiO2 content, the CPs showed band gaps in lower energy, smaller surface areas and the higher content of Ti3+ ions. Compared with pure TiO2 and others CPs samples, CPs-382 sample showed the highest photoactivity due to the optimum TiO2 content and surface area besides the synergic effect of photocatalytic degradation of TiO2 and adsorptive property of GAC. In addition, the CPs could be very easily reclaimed, recycled and reused for methyl orange removal while high photoactivity is pre-served.
文摘Carbon dots(CDs)have gained unprecedented attention as a novel luminescent zero-dimensional carbon nanomaterial owing to their diverse industrial applications.Herein,we reported the sus-tainable synthesis of fluorescent CDs from papaya peel waste,acting as a natural carbon orig-inator.As-prepared CDs and reduced graphene oxide(RGO)were fabricated in the composites through a facile one-step hydrothermal method.Synthesized RGO/CDs(RC)nanocomposites were characterized using spectroscopic,diffraction,and electron-microscopic techniques.Nanocom-posites with variable RGO to CD mass ratios were tested for photodegradation of textile dye methylene blue(MB).The highest photocatalytic activity(degradation efficiency of 87%in 135 min)was obtained in the nanocomposite containing a 2꞉1 mass ratio(RC2).The RGO sheets in the nanocomposite acted as media for electron acceptors,promoting the fast transfer and sep-aration of photoinduced electrons during CDs excitation,thus preventing the recombination of the electron and holes.Based on the agar well diffusion assay,the nanocomposites exhibited ex-cellent antibacterial activity than other tested materials against Bacillus subtilis(Gram-positive)and Pseudomonas aeruginosa(Gram-negative)bacterium.The largest inhibition zone area(22 mm),i.e.,the highest antimicrobial activity,was obtained in the nanocomposite tested against Gram-positive strains.Taken together,the synergistic effect of RGO and CDs enhanced the pho-tocatalytic and antibacterial performance of synthesized nanocomposite material.
