Fe doped CdS nanoparticles (Cd1−xFexS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman and UV–vis spectrometer. The XRD and TEM measurements show that the size of crystallites is in the range of 2–10nm. With increased the Fe doping concentration, the position of the Raman bands shifted towards higher wavenumbers and their intensities decreased drastically. Optical measurements indicated that the absorption band edge shifted towards longer wavelength upon Fe doping. Direct allowed band gap of undoped and Fe doped CdS nanoparticles measured by UV–vis spectrometer were 2.3 and 2.2eV at 100°C, respectively. Photocatalytic activities of CdS and Fe doped CdS were evaluated by irradiating the solution of methylene blue (MB) and sample under visible light. It was found that Fe doped CdS bleaches MB much faster than undoped CdS upon its exposure to the visible light. The optimum Fe/Cd ratio was observed to be 3mol% for photocatalytic applications. In contrast, little degradation was observed for the pure CdS powder.

Cu doped ZnS nanoparticles (Zn1−xCuxS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope, high resolution transmission electron microscope, ultraviolet-visible and photoluminescence spectrometer. The X-ray diffraction and high resolution transmission electron microscope studies show that the size of crystallites is in the range of 2–10nm. XRD study revealed that the samples are composed of cubic phase without doping and at 3mol% Cu doping concentration while at the doping of 5mol% and 10mol% Cu, phase transition from cubic blende to hexagonal phase occurs in ZnS. Photocatalytic activities of ZnS and 3, 5 and 10mol% Cu doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Cu doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to the ultraviolet light. The optimal Cu/Zn ratio was observed to be 3mol% for photocatalytic applications.

Fe doped ZnS nanoparticles (Zn1−xFexS; where x = 0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, ultraviolet–visible and photoluminescence spectrometer. The X-ray diffraction and transmission electron microscope studies show that the size of crystallites is in the range of 2–10 nm. Photocatalytic activities of ZnS and 3, 5 and 10 mol% Fe doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Fe doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to ultraviolet light. The optimal Fe/Zn ratio was observed to be 3 mol% for photocatalytic applications.

Undoped and silver-doped TiO2 nanoparticles (Ti1−x Ag x O2, where x = 0.00–0.10) were synthesized by a sol–gel method. The synthesized products were characterized by X-ray diffraction (XRD), particle size analyzer (PSA), scanning electron microscope (SEM), and UV–Visible spectrophotometer. XRD pattern confirmed the tetragonal structure of synthesized samples. Average crystallite size of synthesized nanoparticles was determined from X-ray line broadening using the Debye–Scherrer formula. The crystallite size was varied from 8 to 33 nm as the calcination temperature was increased from 300 to 800 °C. The incorporation of 3 to 5% Ag+ in place of Ti4+ provoked a decrease in the size of nanocrystals as compared to undoped TiO2. The SEM micrographs revealed the agglomerated spherical-like morphology of particles. SEM, PSA, and XRD measurements show that the particles size of the powder is in nanoscale. Optical absorption measurements indicated a red shift in the absorption band edge upon silver doping. Direct allowed band gap of undoped and Ag-doped TiO2 nanoparticles measured by UV–Vis spectrometer were 3.00 and 2.80 eV, respectively, at 500 °C.

Mn-doped TiO(2) nanoparticles (Ti(1-)(x)Mn(x)O(2); where x=0.00-0.10) were synthesized by sol-gel method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and UV-Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and measurements show that the size of crystallites is in the range of 10-20 nm. Optical measurements indicated a red shift in the absorption band edge after Mn doping. Direct allowed band gap of undoped and Mn-doped TiO(2) nanoparticles measured by UV-Vis spectrometer were 3.00 and 2.95 eV at 300 °C, respectively. Photocatalytic activities of TiO(2) and Mn doped TiO(2) were evaluated by irradiating the sample solution of methylene blue (MB) dye under ultraviolet and visible light exposure. It was found that Mn-doped TiO(2) bleaches MB much faster than undoped TiO(2) upon its exposure to the visible light as comparison to ultraviolet light. The experiment demonstrated that the photodegradation efficiency of Mn-doped TiO(2) was significantly higher than that of undoped TiO(2) upon its exposure to visible light.

Nanocrystals of undoped and zinc doped cadmium sulphide (Cd1-xZnx S, where x = 0.00 to 0.10) were synthesized by chemical precipitation method. Structural characterization of as synthesized semiconductor nanoparticles was performed by X-ray diffraction pattern while optical characterization were done by UV-Visible absorption spectroscopy. XRD pattern showed that the synthesized Zn doped CdS nanoparticles have wurtzite hexagonal structure with 3-39 nm average crystallite size. Optical absorption measurements indicated red shift in the absorption band edge upon Zn doping. Direct allowed band gap of undoped and Zn-doped CdS nanoparticles measured by UV-Visible spectrophotometer were 2.4 to 2.2 eV at 500 degrees C.

Ag-doped ZnO nanoparticles (Zn1−xAgxO; where x = 0.00–0.05) were synthesized by chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope (SEM), transmission electron microscope (TEM) and UV–Vis spectrometer. The SEM and TEM micrographs revealed the agglomerated spherical-like morphology and the measurements show that the size of crystallites is in the range of 10–40 nm. Optical measurements indicated a red shift in the absorption band edge after Ag doping. The band gap values of as prepared undoped and doped with silver samples were found to decrease with increase in temperature from 300 to 800 °C. Photocatalytic activities of ZnO and Ag doped ZnO were evaluated by irradiating the sample solution to ultraviolet light by taking methylene blue as organic dye. The experiment demonstrated that the photo-degradation efficiency of 1 mol% Ag-doped ZnO was significantly higher than that of undoped and 2–5 mol% Ag doped ZnO under ultraviolet light irradiation.

Nanoparticles of undoped and manganese doped zinc sulphide (Zn1-xMnxS, where x = 0.00, 0.03, 0.05 and 0.10) were synthesized by chemical precipitation method. Structural characterization of as synthesized semiconductor nanoparticles were performed by X ray diffraction pattern (XRD) while optical characterization were done by UV-Visible absorption spectroscopy. XRD pattern showed that the synthesized Mn doped ZnS nanoparticles have cubic structure with 3-4 nm average crystallite size. Optical absorption measurements indicated red shift in the absorption band edge upon Mn doping. Direct allowed band gap of undoped and Mn- doped ZnS nanoparticles measured by UVVIS spectro-photometer were 2.95 to 2.85 eV at 400 o C.

Nanocrystals of undoped and nickel-doped zinc oxide (Zn1−x Ni x O, where x = 0.00–0.05) were synthesized by the coprecipitation method. Crystalline size, morphology, and optical absorption of prepared samples were determined by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), and UV–visible spectrometer. XRD and SEM studies revealed that Ni-doped ZnO crystallized in hexagonal wurtzite structure. Doping of ZnO with Ni2+ was intended to enhance the surface defects of ZnO. The incorporation of Ni2+ in place of Zn2+ provoked an increase in the size of nanocrystals as compared to undoped ZnO. Crystalline size of nanocrystals varied from 10 to 40 nm as the calcination temperature increased. Enhancement in the optical absorption of Ni-doped ZnO indicated that it can be used as an efficient photocatalyst under visible light irradiation. Optical absorption measurements indicated a red shift in the absorption band edge upon Ni doping. The band gap value of prepared undoped and Ni-doped ZnO nanoparticles decreased as annealing temperature was increased up to 800 °C.

Nanocrystals of undoped and iron doped zinc oxide (Zn1-xFexO, where x = 0.00 to 0.05) were synthesized by coprecipitation method. Crystalline phases and optical absorption of prepared samples were determined by X-ray diffraction and UV-visible spectrophotometer. The average particles size was determined from X-ray line broadening. X-ray analyses revealed the formation of the hexagonal wurtzite ZnO with secondary phase in the Fe-doped sample. The incorporation of iron in place of zinc provoked an increase in the size of nanocrystals as compared to undoped ZnO. Crystalline size of nanocrystals varied from 27 to 41 nm as the calcinations temperature increased. Optical absorption measurement indicated red shift in the absorption band edge upon Fe doping. The band gap value was found to decrease from 2.90 to 2.85 eV with iron (5 %) doping at 800 degrees C.

Nanocrystals of undoped and nickel doped zinc oxide (Zn1-xNixO, where x = 0.00 to 0.05) were synthesized by coprecipitation method. X-ray study revealed that Ni doped ZnO crystallized in hexagonal wurtzite structure. The incorporation of Ni2+ in the place of Zn2+ provoked an increase in the size of nanocrystals as compared to undoped ZnO. Crystalline size of nanocrystals varied from 10 to 40 nm as the calcinations temperature increased. Optical absorption measurements indicated red shift in the absorption band edge upon Ni doping. The band gap value of prepared undoped and nickel doped ZnO nanoparticles decreased as annealing temperature was increased up to 800 degrees C.

Nanocrystals of undoped and copper doped zinc oxide (Zn1-x Cu x O (where x = 0.00 to 0.05) were synthesized by coprecipitation method. Crystalline phases and optical absorption of prepared samples were determined by X-ray diffraction and UV-visible spectrophotometer. The average particles size was determined from X-ray line broadening. X-ray analyses reveals that Cu doped ZnO crystallizes in hexagonal wurtzite structure. The incorporation of Cu+2 in the place of Zn2+ provoked an increase in the size of nanocrystals as compared to undoped or pure ZnO. Optical absorption measurement indicates red shift in the absorption band edge upon Cu doping. The band gap decreases from 3.15 eV to 2.92 eV with copper (5 %) doping at temperature 450 oC.