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Novel N/Carbon Quantum Dot Modified MIL-125(Ti) Composite for Enhanced Visible-Light Photocatalytic Removal of NO

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journal contribution
posted on 24.03.2020, 23:04 by Meijuan Chen, Xiaoyan Wei, Liaoliao Zhao, Yu Huang, Shun-cheng Lee, Wingkei Ho, Kehao Chen
Highly efficient and stable photocatalysts were synthesized at room temperature by modifying MIL-125­(Ti) with N-doped carbon quantum dots (N/CM­(Ti)). The N/CM­(Ti) with 2.5 vol % N doped carbon quantum dots (N/CQDs) had the best light absorption and visible-light photocatalytic nitrogen oxide (NO) removal efficiency (approximately 49%). It was found through X-ray photoelectron spectroscopy analysis that a N–Ti–O bond was formed in the 2.5 vol % N/CM­(Ti), which is more conducive to charge transfer. Photocurrent and electrochemical impedance data also showed that the carrier separation efficiency of 2.5 vol % N/CM­(Ti) was significantly superior to that of MIL-125­(Ti). In addition, the TiIII–TiIV of MIL-125­(Ti) acts as the active center for photocatalytic removal of NO. Two possible electron migration paths were proposed: electron transfer from N/CQDs to TiIII–TiIV center of MIL-125­(Ti) due to the photoinduced electron transfer property of N/CQDs, and absorption of UV light generated from the N/CQDs by the terephthalic acid ligand followed by electron transfer to metal active sites for photocatalytic removal of NO.