Effect of annealing temperature on optical properties and photocatalytic properties of TiO2:N 8% thin film for rhodamine B degradation

Abstract

Titanium dioxide (TiO2) is a widely studied photocatalyst for the degradation of organic pollutants from wastewater. This semiconductor is more potential than other semiconductors because of its stability, non-toxic, low cost, and commercial availability. A thin film of TiO2:N 8% was deposited on a glass substrate using a sol-gel method with a spray coating deposition at a temperature of 450 °C. Precursors used in the synthesis of TiO2:N 8% are titanium (IV) isopropoxide (TTiP), 2-propanol, acetic acid, methanol, and urea as the source of nitrogen doping. Thin film TiO2:N 8% of subsequent deposition results at annealing at temperatures 400 °C, 500 °C, and 600 °C. Optical properties of TiO2:N 8% were tested using a UV–vis spectrophotometer at 200–500 nm wavelength range. The photocatalytic properties of TiO2:N 8% thin films were tested by degradation of a solution of Rhodamine B (RhB) 10 ppm using sunlight and UV C light for 3 h. The energy gap in thin film TiO2:N 8% sequentially from Without Annealing, Annealing 400 °C, Annealing 500 °C, Annealing 600 °C has a value of 3.28 eV; 3.26 eV; 3.08 eV; and 2.95 eV, respectively. The material TiO2:N 8% without annealing has a grain shape having a diameter of 0.5 μm to 1 μm, while for TiO2:N 8% annealing 400 °C has the same grain shape without annealing. The composition of nitrogen atoms in the TiO2:N sample of 8% by 0.2%. The efficiency of degradation shows the properties of TiO2:N 8% photocatalyst with annealing for the better. The degradation process using 400 °C annealing temperature yields a thin film TiO2:N 8% with better properties under UV C lamp of 89.22% in 180 min. Annealing temperature increase yields TiO2:N 8% thin film with improved photocatalyst properties in sunlight with an annealing temperature of 600 °C at 79.30% in 180 min.