g-C3N4修饰的TiO2纳米阵列光电催化氧化去除氰化物

通过水热法制备了TiO_2纳米棒(TiO_2NRs)电极,然后通过液相生长法将石墨相氮化碳(g-C_3N_4)负载到TiO_2NRs电极上制备出TiO_2NRs/g-C_3N_4电极.电极的XRD和SEM表征结果表明,g-C_3N_4成功负载到了TiO_2NRs上.将TiO_2NRs/g-C_3N_4电极作为光阳极用于光电催化体系中,并于反应体系中不断曝入O_2,结果发现,与钛片相比,碳气凝胶(CA)电极作为阴极时,反应150 min后CN~-的去除率由13.4%提高到53.1%.与PC过程和EC过程相比,PEC过程对CN~-的去除效果最好.不同光阳极的对比表明,g-C_3N_4与TiO_2的复合可以大大提高阴极H_2O_2产量从而促进CN~-的去除.实验表明,外加偏压的增大可以提高体系中H_2O_2的产量从而增强CN~-的去除效果,CN~-的去除率随CN~-初始浓度的增大而减小.体系的稳定性实验表明,制备的TiO_2NRs/g-C_3N_4电极具有较好的稳定性.最后提出了通过碳气凝胶阴极利用光生电子原位产H_2O_2,强化了TiO_2NRs/g-C_3N_4复合电极作为光阳极对水中CN~-的去除效果的反应机理.

Photoelectrocatalytic oxidation of cyanides by the g-C3N4 modified TiO2 nanoarray photoanode

The TiO₂ nanoarrays NRs electrodes have been constructed through hydrothermal approach, and was followed by a liquid-based reaction in which the g-C₃N₄ were fabricated on the TiO₂ NRs electrodes. The TiO₂ NRs/g-C₃N₄ electrodes were characterized with XRD and SEM, which illustrated that g-C₃N₄ were successfully decorated on the TiO₂ NRs electrodes. The TiO₂ NRs/g-C₃N₄ electrodes were used as photoanodes in photoelectrocatalysis (PEC) system, and the oxygen was bubbled into the system. After 150 min reaction, compared with the Ti plate as the anode, the carbon aerogel cathode can enhance the removal efficiency of CN^- from 13.4% to 53.1%. Compared with the PC process and EC process, the PEC process exhibits the best removal performance of CN^-. The PEC process with different photoanode have demonstrated that the TiO₂ modified by g-C₃N₄ can greatly improve the H₂O₂ production on the cathode so as to promote the CN^- removal efficiency. The increase of the applied bias potential can improve the yield of H₂O₂ in the system and thus enhance the removal efficiency of CN^-. The removal efficiency of CN^- is gradually decreased with the increase of CN^- initial concentration. The stability experiments showed that the TiO₂ NRs/g-C₃N₄ electrodes have a good stability. Finally, a systematically mechanism of using photo-induced electrons in situ production H₂O₂ through the carbon aerogel cathode which enhanced the CN^- removal ability of TiO₂ NRs/g-C₃N₄ photoanode was proposed.