Enhanced photocatalytic performance of nitrogen-doped TiO2 Nanotube arrays using a simple annealing process

Phuoc Huu Le*, Le Trung Hieu, Tu Ngoc Lam, Nguyen Thi Nhat Hang, Nguyen Van Truong, Le Thi Cam Tuyen, Pham Thanh Phong, Jih-Perng Leu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Nitrogen-doped TiO2 nanotube arrays (N-TNAs) were successfully fabricated by a simple thermal annealing process in ambient N2 gas at 450 °C for 3 h. TNAs with modified morphologies were prepared by a two-step anodization using an aqueous NH4F/ethylene glycol solution. The N-doping concentration (0-9.47 at %) can be varied by controlling N2 gas flow rates between 0 and 500 cc/min during the annealing process. Photocatalytic performance of as-prepared TNAs and N-TNAs was studied by monitoring the methylene blue degradation under visible light (λ ≥ 400 nm) illumination at 120 mW˙cm-2. N-TNAs exhibited appreciably enhanced photocatalytic activity as compared to TNAs. The reaction rate constant for N-TNAs (9.47 at % N) reached 0.26 h-1, which was a 125% improvement over that of TNAs (0.115 h-1). The significant enhanced photocatalytic activity of N-TNAs over TNAs is attributed to the synergistic effects of (1) a reduced band gap associated with the introduction of N-doping states to serve as carrier reservoir, and (2) a reduced electron-hole recombination rate.

Original languageEnglish
Article number618
Issue number12
StatePublished - 24 Nov 2018


  • Band gap
  • Modified TiO
  • N-doped TNAs
  • Photocatalytic activity
  • Thermal annealing
  • Two-step anodization

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