Preparation of g-C3N4 quantum dot-TiO2/conductive attapulgite composites and their photocatalytic performance
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摘要: 通过水热法在导电凹凸棒石(C-ATP)表面原位生长TiO2纳米棒制得毛虫状结构的TiO2/C-ATP复合材料，然后以TiO2/C-ATP为载体，在TiO2纳米棒表面进一步复合g-C3N4量子点(CNQD)成功制备了多级结构的CNQD-TiO2/C-ATP异质结光催化材料。利用XRD、FTIR、SEM/TEM、紫外-可见吸收光谱(UV-Vis-DRS)、荧光发射光谱(PL)、BET比表面积分析仪和光电化学等技术对样品进行表征。在可见光照射下，考察了样品对盐酸四环素(TC)的光催化降解能力。结果表明：与TiO2/C-ATP和CNQD相比，CNQD-TiO2/C-ATP大幅提高了可见光响应、吸收能力和光生电子-空穴对的分离效率。当光照时间为120 min时，CNQD-TiO2/C-ATP对TC去除率可达88%。Abstract: TiO2/C-ATP composites consisting of palmerworm-like TiO2 nanorods in-situ growth on the surface of conductive attapulgite (C-ATP) were constructed via a hydrothermal approach. Then TiO2/C-ATP was used as the carrier to uniformly load carbon nitride quantum dots (CNQD) to successfully prepare hierarchical CNQD-TiO2/C-ATP heterojunction photocatalysts. The obtained samples were characterized by XRD, FTIR, SEM/TEM, ultraviolet-visible (UV-Vis-DRS), photoluminescence (PL), Brunauer-emmett-teller (BET) specific area analyzer and photoelectrochemistry. The degradation ability of the sample to tetracycline hydrochloride (TC) was investigated under visible light. The results show that CNQD-TiO2/C-ATP composites dramatically enhance the visible light response, the absorption capacity and the separation of photogenerated electron-hole pairs compared to TiO2/C-ATP and CNQD. After 120 min irradiation, the degradation rate of CNQD-TiO2/C-ATP to remove TC can achieve 88%.
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图 1 g-C3N4量子点(CNQD)、导电凹凸棒石(C-ATP)、TiO2/C-ATP和CNQD-TiO2/C-ATP复合材料的XRD图谱
Figure 1. XRD patterns of g-C3N4 quantum dots (CNQD), conductive attapulgite (C-ATP), TiO2/C-ATP and CNQD-TiO2/C-ATP composite
图 2 TiO2/C-ATP、CNQD和CNQD-TiO2/C-ATP复合材料的FTIR和XPS图谱
Figure 2. FTIR and XPS spectra of TiO2/C-ATP, CNQD and CNQD-TiO2/C-ATP
图 3 C-ATP (a)、TiO2/C-ATP ((b), (c))和CNQD-TiO2/C-ATP ((d)~(f))的TEM图像
Figure 3. TEM images of C-ATP (a), TiO2/C-ATP ((b),(c)) and CNQD-TiO2/C-ATP ((d)-(f))
图 5 C-ATP、TiO2/C-ATP、CNQD和CNQD-TiO2/C-ATP的UV-Vis-DRS图谱 (a) 和带隙图 (b)
Figure 5. UV-Vis-DRS spectra (a) and the plots of band gap energies (b) of C-ATP, TiO2/C-ATP, CNQD and CNQD-TiO2/C-ATP
图 6 TiO2/C-ATP、CNQD和CNQD-TiO2/C-ATP的PL图谱
Figure 6. PL spectra of TiO2/C-ATP, CNQD and CNQD-TiO2/C-ATP
图 7 TiO2/C-ATP、CNQD和CNQD-TiO2/C-ATP的I-t (a)和EIS曲线(b)
Figure 7. I-t (a) and EIS curves (b) of TiO2/C-ATP, CNQD and CNQD-TiO2/C-ATP
图 8 C-ATP、TiO2/C-ATP和CNQD-TiO2/C-ATP的N2吸附-脱附(a)和孔径分布曲线(b)
Figure 8. N2 adsorption-desorption isotherms (a) and pore-size distributions (b) of C-ATP，TiO2/C-ATP and CNQD-TiO2/C-ATP
图 9 不同时间的盐酸四环素(TC)光催化产物的UV-Vis-DRS图谱 (a) 和可见光下不同催化剂对TC的去除率曲线 (b)
Figure 9. UV-Vis-DRS spectra of tetracycline hydrochloride (TC) photocatalytic products at different time periods (a) and curves of TC removal rate of different catalysts under visible light (b)
CTOC—Concentration of total organic carbon
图 10 TC初始浓度 (a) 和光催化剂添加量 (b) 对TC去除率的影响
Figure 10. Effect of initial TC concentration (a) and photocatalyst addition amount (b) on TC removal rate
图 11 CNQD-TiO2/C-ATP复合材料循环5次试验后的TC降解效率对比
Figure 11. TC removal rate comparison of denitrification performance of the CNQD-TiO2/C-ATP composite photocatalysts after cycling 5 times
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