High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine...High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM, BET, FFIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange （MO） and 4-chlorophenol （4- CP） as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO2 nanoparticles were investigated. Results show that Gd and P doping enhances Ti02 surface textural properties by forming Ti O Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO2 with rate constant ofkapp - 1.28 ~ 10-2 min-1 for MO and kapp ~ 0.94 ~ 10-2 min-1 for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tri- doped Ti02 is due to the synergistic effect of enhanced surface chemistry and textural properties, increased number of surface adsorbed hydroxyl groups and organic species, improved visible light ab- sorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.展开更多
The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For...The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For the Fe-Gd system, the compounds Fe23Gd6,Fe3Gd and Fe2Gd with no solubility ranges were treated as stoichiometric compounds. According to the CaCu5-type structure of the intermetallic compounds Fe17Gd2,it was reasonable to adopt a three-sulattice model （Fe2,Gd）Gd2Fe15 in the Fe-Gd system, and this model was also adopted as （Co2,Fe2,Gd）（Co2,Gd）2（Co,Fe）15 to describe the compounds （Co,Fe）17Gd2 and （Co,Fe）5Gd in the Co-Fe-Gd ternary system. The other compounds were treated as the line compounds （Co,Fe）mGdn and no ternary compound had been reported in the Co-Fe-Gd system. The thermodynamic description of the Co-Fe and Co-Gd system were taken from literatures. A self-consistent thermodynamic description of the Co-Fe-Gd system was obtained.展开更多
基金Project supported by the Research office of the Sharif University of Technology(90212681)
文摘High performance Fe-Gd-P tri-doped TiO2 nanoparticles （1 at% for each dopant） were successfully synthesized by a modified sol-gel method. Various analytical and spectroscopic techniques were carried out to determine the physicochemical properties of the prepared samples, including XRD, EDX, FESEM, BET, FFIR, XPS, PL, EIS and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activities of prepared samples were evaluated by photo degradation of methyl orange （MO） and 4-chlorophenol （4- CP） as model pollutants under visible light irradiation. Effects of each dopant on different properties of TiO2 nanoparticles were investigated. Results show that Gd and P doping enhances Ti02 surface textural properties by forming Ti O Gd and Ti-O-P bonds. It is found that Gd plays a superior role in increasing oxygen vacancies and organic species on TiO2 surface. Gd doping also facilitates transferring of the photo-induced charge carriers to the surface adsorbed species. The enhanced electronic band structure and visible light response, as well as high electron lifetime of Fe-Gd-P tri-doped sample is mainly attributed to Fe and Gd doping. The tri-doped TiO2 with rate constant ofkapp - 1.28 ~ 10-2 min-1 for MO and kapp ~ 0.94 ~ 10-2 min-1 for 4-CP, shows the highest photodegradation rate among all samples including undoped and single doped samples. The improved photocatalytic performance of Fe-Gd-P tri- doped Ti02 is due to the synergistic effect of enhanced surface chemistry and textural properties, increased number of surface adsorbed hydroxyl groups and organic species, improved visible light ab- sorption, increased lifetime of the photo-induced electron/hole pairs and boosted interfacial charge transfer.
基金Project supported by National Natural Science Foundation of China(50934011,50971027)
文摘The Fe-Gd and Co-Fe-Gd systems were optimized by means of the CALPHAD （CALculation of PHAse Diagram） technique. The solution phases, liquid, bcc, fcc and hcp, were described by the substitutional solution model. For the Fe-Gd system, the compounds Fe23Gd6,Fe3Gd and Fe2Gd with no solubility ranges were treated as stoichiometric compounds. According to the CaCu5-type structure of the intermetallic compounds Fe17Gd2,it was reasonable to adopt a three-sulattice model （Fe2,Gd）Gd2Fe15 in the Fe-Gd system, and this model was also adopted as （Co2,Fe2,Gd）（Co2,Gd）2（Co,Fe）15 to describe the compounds （Co,Fe）17Gd2 and （Co,Fe）5Gd in the Co-Fe-Gd ternary system. The other compounds were treated as the line compounds （Co,Fe）mGdn and no ternary compound had been reported in the Co-Fe-Gd system. The thermodynamic description of the Co-Fe and Co-Gd system were taken from literatures. A self-consistent thermodynamic description of the Co-Fe-Gd system was obtained.
