Development of Defect‐Free Rutile‐TiO2 by N‐Doping and its Enhanced Photocatalytic Efficiency

Abstract

AbstractUndoped and Nitrogen‐doped Rutile‐TiO2 (R‐TiO2) nano‐spindles were synthesized via sol‐gel synthesis. XPS studies revealed the combined presence of Ti4+ and Ti3+ ionic states in the undoped sample. Among them, Ti3+ was observed contributing a trap state in its Photoluminescence spectrum. Whereas, nitrogen doping was found resulting in the presence of Ti4+ state alone without Ti3+, confirmed from the XPS measurement. These corresponding trap states of Ti3+ were also found missing in the photoluminescence spectrum. XRD characterization confirmed the crystallization of rutile structure and their corresponding HR‐TEM studies showed the crystallization of nano‐spindles. Raman studies reveal a grouped red shift in the peak positions of A1g, and Eg peaks and a blue shift of second order peak (241 cm−1) position, especially in N‐doped samples. The values of Flat‐band (FB) potential derived from Electrochemical impedance (EIS) measurement found varied from −0.48 V–−0.71 V for N‐doped samples, which confirms that the energy level of N‐doped R‐TiO2 is higher than the reduction potential of “O2−” (−0.33 V). Hence, the R‐TiO2(N)/electrolyte interface seems facilitating the synergetic charge transport, which in turn exhibits an improvement in the Methylene Blue (MB) dye degradation efficiency from 63 % (undoped R‐TiO2) to 81 % (2 wt. % of N‐doping).