Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, re...Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.展开更多
The shape of nanostructure has important effects on their properties, therefore in this study, we have prepared and characterized three different morphologies of WO_3 nanostructures i.e. nanorod, nanosphere and nanopl...The shape of nanostructure has important effects on their properties, therefore in this study, we have prepared and characterized three different morphologies of WO_3 nanostructures i.e. nanorod, nanosphere and nanoplate for surveying shape effect on their photocatalytic properties toward degradation of Rhodamine B （RhB） dye. Obtained results show that nanoplate WO_3 in comparison with others has the best photocat- alytic activity. According to SEM, and photocatalytic degradation results, the reason for this behavior is the sharp edges and corners of WO_3 nanoplates. Because of their low coordination number, atoms located in the edges and comers of the WO_3 nanoplates have more activity, adsorb more RhB and therefore give more photocatalytic activity to the WO_3 nanoplates. Using of different scavengers showed that hydroxyl radicals are mainly responsible for photocatalytic activity of WO_3 nanoplates and nangspheres but for WO_3 nanorods, superoxide radicals are the main photocatalytic degradation agents.展开更多
Pollution of water resources with pesticide compounds has raised serious environmental problems,and for photocatalytic degradation of these pollutants,thin film photocatalysts are preferred to colloidal ones due to th...Pollution of water resources with pesticide compounds has raised serious environmental problems,and for photocatalytic degradation of these pollutants,thin film photocatalysts are preferred to colloidal ones due to the separation problem of colloidal nanoparticles.In this work,nanostructured TiO_2 and N-doped TiO_2 thin films with high transparency were deposited on glass and quartz substrates through sonochemical–chemical vapor deposition(CVD)method.The films prepared on glass and quartz substrates had nanocubic and nanospherical morphology,respectively.The presence of N atoms in the structure of TiO_2 resulted in a decrease in the band gap energy of TiO_2 and also in the reduction of photogenerated electron–hole recombination rate.Furthermore,the presence of N atoms induced the formation of Ti^(3+)species which can act as hole trapping centers.The prepared thin films were also used for the visible light photocatalytic degradation of paraoxon pesticide.According to these results among the prepared thin films,the N-doped TiO_2 thin films have higher photocatalytic activity than pure TiO_2 thin films.Moreover,in comparison with the thin films deposited on quartz substrate,the films on glass substrate have higher photocatalytic performance,which can be related to the special nanocubic morphology of these samples.展开更多
文摘Ag/TiO2/freeze-dried graphene nanocomposites have been prepared via a facile one-step solvothermal method for the photocatalytic degradation of Rh B under visible light irradiation. During the solvothermal process, reduction of graphene oxide and loading of Ag/TiO2nanoparticles on graphene sheets were achieved. Investigation of chemical state of products showed that covering of Ag/TiO2surface with higher weight ratio of graphene resulting in that Ag metals in Ag/TiO2were oxidized to Ag2 O in nanocomposite structure after solvothermal process. Degree of photocatalytic activity enhancement strongly depends on the coverage of Ag/TiO2surface by porous graphene. The sample of 1 wt% porous graphene hybridized Ag/TiO2showed the highest photocatalytic activity, which is related to high migration efficiency of photoinduced of electrons and reduction of electron–hole recombination rate due to high electrical conductivity of graphene. Expanding of absorption to visible light region was ascribed to surface plasmon resonance effect of Ag metals and presence of graphene. Investigation of photocatalytic performance of formic acid as a dye-less organic pollutant showed that dye sensitization effect of Rh B molecules during evaluation of photocatalytic performance was negligible.
文摘The shape of nanostructure has important effects on their properties, therefore in this study, we have prepared and characterized three different morphologies of WO_3 nanostructures i.e. nanorod, nanosphere and nanoplate for surveying shape effect on their photocatalytic properties toward degradation of Rhodamine B （RhB） dye. Obtained results show that nanoplate WO_3 in comparison with others has the best photocat- alytic activity. According to SEM, and photocatalytic degradation results, the reason for this behavior is the sharp edges and corners of WO_3 nanoplates. Because of their low coordination number, atoms located in the edges and comers of the WO_3 nanoplates have more activity, adsorb more RhB and therefore give more photocatalytic activity to the WO_3 nanoplates. Using of different scavengers showed that hydroxyl radicals are mainly responsible for photocatalytic activity of WO_3 nanoplates and nangspheres but for WO_3 nanorods, superoxide radicals are the main photocatalytic degradation agents.
文摘Pollution of water resources with pesticide compounds has raised serious environmental problems,and for photocatalytic degradation of these pollutants,thin film photocatalysts are preferred to colloidal ones due to the separation problem of colloidal nanoparticles.In this work,nanostructured TiO_2 and N-doped TiO_2 thin films with high transparency were deposited on glass and quartz substrates through sonochemical–chemical vapor deposition(CVD)method.The films prepared on glass and quartz substrates had nanocubic and nanospherical morphology,respectively.The presence of N atoms in the structure of TiO_2 resulted in a decrease in the band gap energy of TiO_2 and also in the reduction of photogenerated electron–hole recombination rate.Furthermore,the presence of N atoms induced the formation of Ti^(3+)species which can act as hole trapping centers.The prepared thin films were also used for the visible light photocatalytic degradation of paraoxon pesticide.According to these results among the prepared thin films,the N-doped TiO_2 thin films have higher photocatalytic activity than pure TiO_2 thin films.Moreover,in comparison with the thin films deposited on quartz substrate,the films on glass substrate have higher photocatalytic performance,which can be related to the special nanocubic morphology of these samples.
