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

Undoped and Nitrogen‐doped Rutile‐TiO 2 (R‐TiO 2 ) nano‐spindles were synthesized via sol‐gel synthesis. XPS studies revealed the combined presence of Ti 4+ and Ti 3+ ionic states in the undoped sample. Among them, Ti 3+ was observed contributing a trap state in its Photoluminescence spectrum. Whereas, nitrogen doping was found resulting in the presence of Ti 4+ state alone without Ti 3+ , confirmed from the XPS measurement. These corresponding trap states of Ti 3+ 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 A 1g , and E g peaks and a blue shift of second order peak (241 cm −1 ) position, especially in N‐doped samples. The values of Flat‐band (F B ) 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‐TiO 2 is higher than the reduction potential of “O 2 − ” (−0.33 V). Hence, the R‐TiO 2 (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‐TiO 2 ) to 81 % (2 wt. % of N‐doping).