Titanium dioxide (TiO2) is one of popular semiconductor materials that usually used for photocatalytic application. Recent studies show the improvement of TiO2 photocatalytic activity through nitrogen doping (N-doped TiO2). In this study, we focused on the synthesis and characterization of N-doped TiO2. Ultrasonic assisted synthesis or sonochemical method was used to prepare N-doped TiO2 polycrystalline powder under room temperature. X-ray diffractometer (XRD), and diffuse reflectance ultraviolet-visible spectrophotometer (DR-UV) were employed to evaluate physical properties of N-doped TiO2. XRD pattern exhibited that all samples have anatase crystalline phase and crystallite size decrease with increase of N dopant concentration. The absorbance spectra showed the slight shift toward higher wavelength (red shift) and from Kubelka-Munk function the band gaps were getting smaller with increase of N content. The increase of photocatalytic activity under solar radiation was achieved by N-doped TiO2 samples with highest efficiency about 81 % for 5% of N doping concentration.

Nano particle of N-doped TiO2 with the size of 21.42 nm was successfully created using sonochemical method. Concentration of Nitrogen (N) doping on TiO2 was calculated using mole ratio of Urea and TTiP. Doping variations were performed by doping 5% to 9% N, and did not change the crystallite size and strain. The nanoparticle produced has a polycrystalline structure with a dominant diffraction peak (101). Doping N into TiO2 affects the morphology of particle surface, thus tending to shrink. Results of photo catalysis on liquid samples of MB 20 ppm dye indicate that the addition of N improves the degradation ability of TiO2, with the highest value on sample T5 of 85% and with a rate of degradation kinetics of 0.024 ppm/minute.

N-ZnO thin layer is widely used in application of wastewater photo catalyst. N-ZnO thin films have been successfully deposited on glass substrate using spray coating technique at 450 °C with varying concentrations of N from Urea source. XRD test results showed that the N-ZnO has a polycrystalline structure with diffraction field (100), (002), (101) and (110). The presence of nitrogen atoms in the lattice of ZnO causes a shift in diffraction angle between 0.08o - 0.18o. N-ZnO thin layer showed the occurrence of tensile strain. Surface morphology of N-ZnO is shaped like mine (like root). All samples have band gap energies lower than that of ZnO and the smallest is sample N6 with Eg = 3.249 eV. The presence of nitrogen atom increases surface roughness and decreases band gap energy.

Pollution is caused by dangerous heavy metal such as Pb, Cu and Zn are toxic in the body tissues of organisms such as fish in high concentrations, it will be harmful to human health The purpose is to create an eco-friendly fish preservative tool with cooling system of thermodynamics and photocatalytic Co doped ZnO nanoparticles. this device can reach temperature 15 o C. Then to reduce dangerous heavy metals and kill bacteria used principle of photocatalytic Co doped ZnO nanoparticles. Co doped ZnO synthesized by sol-gel method. Then proceeded to spray coating and drying with furnace. The result is a purple clear homogeneous solution. From the analysis of the obtained bandgap Co doped ZnO about 2.28 eV and from SEM generated that average particle size Co doped ZnO is 60 nm. From the result of Co doped ZnO can be initiated by visible light and may have antibacterial activity so that this material can be made as a tool to prevent the growth of microorganisms only using regular light Key words : Eco-friendly fish preservative tools; less energy based on cooling dynamic; Nano Co Doped ZnO.