Preparation and antibacterial properties of GO@P-g-C3N4 composite photocatalytic material
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摘要:
通过静电自组装法制备了质子化石墨相氮化碳(P-g-C3N4)涂层的氧化石墨烯(GO)复合材料(GO@P-g-C3N4)，探究其在光催化抗菌方面的应用。通过SEM、TEM、XRD、XPS、Raman、UV-Vis DRS、稳态/瞬态荧光光谱(PL)等对GO@P-g-C3N4复合材料的微观形貌、晶态结构及光电性能进行表征，并通过调控P-g-C3N4的含量对GO@P-g-C3N4复合材料进行了结构优化。在模拟太阳光照射条件下，以大肠杆菌(E. coli)和金黄色葡萄球菌(S. aureus)为实验对象，研究了不同P-g-C3N4含量的GO@P-g-C3N4复合材料的光催化抗菌性能及光照时间对抗菌性能的影响。结果表明：GO与P-g-C3N4以质量比为1∶4合成的GO@P-g-C3N4-80%复合材料，光照100 min后，对E. coli和S. aureus的抑菌率分别为98.80%和95.99%；光照150 min后，对E. coli和S. aureus的抑菌率均达到99%以上，抗菌性能显著优于GO与P-g-C3N4。
Abstract:A protonated graphite carbon nitride (P-g-C3N4) coated graphene oxide (GO) composite material (GO@P-g-C3N4) was prepared via electrostatic self-assembly method, and its application in photocatalytic antibacterial activities was investigated. The micro morphologyies, crystalline structures, and photoelectric properties of the GO@P-g-C3N4 composite material were characterized by SEM, TEM, XRD, XPS, Raman, UV-Vis DRS and steady-state/transient fluorescence spectroscopy (PL), etc. The structure of GO@P-g-C3N4 composite material was optimized by adjusting the content of P-g-C3N4. Under simulated solar light irradiation conditions, E. coli and S. aureus were used as experimental targets to study the photocatalytic antibacterial performance of GO@P-g-C3N4 composites with different P-g-C3N4 contents and the influence of irradiation times on antibacterial performance. It was found that GO@P-g-C3N4-80% composite material synthesized with a mass ratio of 1∶4 between GO and P-g-C3N4 exhibited antibacterial rates against E. coli and S. aureus of 98.80% and 95.99%, respectively after 100 min of illumination. After 150 min of illumination, antibacterial rates against both E. coli and S. aureus exceeded 99%, demonstrating significantly better antibacterial performance compared to individual GO or P-g-C3N4.
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Keywords:
- graphene oxide /
- P-g-C3N4 /
- composite /
- photocatalysis /
- antibacterial performance
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图 1 块状g-C3N4 (B-g-C3N4 ) (a)、质子化石墨相氮化碳(P-g-C3N4) (c)、氧化石墨烯(GO) (e)和 GO@P-g-C3N4 (g)的SEM图像；B-g-C3N4 (b)、P-g-C3N4 (d)、GO (f)和GO@P-g-C3N4 (h)的TEM图像；(i) GO@P-g-C3N4的EDX元素分布图
Figure 1. SEM images of block g-C3N4 (B-g-C3N4) (a), protonated graphite carbon nitride (P-g-C3N4) (c), graphene oxide (GO) (e) and GO@P-g-C3N4 (g); TEM images of B-g-C3N4 (b), P-g-C3N4 (d), GO (f) and GO@P-g-C3N4 (h); (i) EDX images of GO@P-g-C3N4
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图 2 GO、B-g-C3N4、P-g-C3N4和GO@P-g-C3N4的XRD图谱
Figure 2. XRD patterns of GO, B-g-C3N4, P-g-C3N4 and GO@P-g-C3N4
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图 3 (a) P-g-C3N4、GO和GO@P-g-C3N4的XPS全谱图；GO (b)和P-g-C3N4 (c)的O1s高分辨率XPS图谱；GO (d)、P-g-C3N4 (e)和GO@P-g-C3N4 (f)的C1s高分辨率XPS图谱；P-g-C3N4 (g)和GO@P-g-C3N4 (h)的N1s高分辨率XPS图谱；(i) B-g-C3N4、P-g-C3N4、GO和GO@P-g-C3N4的Raman图谱
Figure 3. (a) XPS survey spectra of P-g-C3N4, GO and GO@P-g-C3N4; High-resolution O1s XPS spectra of GO (b) and P-g-C3N4 (c); High-resolution C1s XPS spectra of GO (d), P-g-C3N4 (e) and GO@P-g-C3N4 (f); High-resolution N1s XPS spectra of P-g-C3N4 (g) and GO@P-g-C3N4 (h); (i) Raman spectra of B-g-C3N4, P-g-C3N4, GO and GO@P-g-C3N4
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图 4 P-g-C3N4和GO@P-g-C3N4的N2吸附-解吸等温线(a)及孔径分布图(b)
Va—Quantity adsorbed; STP—Standard temperature and pressure; SBET—BET surface area; Vp—Pore volume; W—Pore size; VTotal—Single point adsorption total pore vlume of pores
Figure 4. N2 adsorption/desorption isotherms (a) and pore size distributions (b) of P-g-C3N4 and GO@P-g-C3N4
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图 5 P-g-C3N4和GO@P-g-C3N4的UV-Vis DRS (a)及对应的 Kubelka-Munk曲线(b)
a—Absorption coefficient; h—Planck constant; v—Frequency
Figure 5. UV-Vis DRS (a) and corresponding Kubelka-Munk curves (b) of P-g-C3N4 and GO@P-g-C3N4
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图 6 P-g-C3N4和GO@P-g-C3N4的光致发光谱图
Figure 6. Photoluminescence spectra of P-g-C3N4 and GO@P-g-C3N4
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图 7 P-g-C3N4和GO@P-g-C3N4的光电流-时间曲线
Figure 7. Photocurrent-time curves of P-g-C3N4 and GO@P-g-C3N4
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图 8 对照组和不同光催化剂对E. coli和S. aureus的光催化抑菌率
Figure 8. Photocatalytic inhibition rates of E. coli and S. aureus under control and different photocatalysts
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图 9 不同光催化剂作用下E. coli和S. aureus菌落琼脂平板照片
Figure 9. Images of the agar plates of bacterial colonies formed by E. coli and S. aureus under different photocatalysts
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图 10 不同质量比GO@P-g-C3N4对E. coli和S. aureus的光催化抑菌率
Figure 10. Photocatalytic inhibition rates of E. coli and S. aureus for GO@P-g-C3N4 under different mass ratios
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图 11 不同质量比GO@P-g-C3N4作用下E. coli和S. aureus菌落琼脂平板照片
Figure 11. Images of the agar plates of bacterial colonies formed by E. coli and S. aureus for GO@P-g-C3N4 under different mass ratios
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图 12 GO@P-g-C3N4-80%在不同光照时间下对E. coli和S. aureus的光催化抑菌率
Figure 12. Photocatalytic inhibition rates of E. coli and S. aureus by GO@P-g-C3N4-80% after different irradiation times
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图 13 GO@P-g-C3N4-80%在不同光照时间下的E. coli和S. aureus菌落琼脂平板照片
Figure 13. Images of the agar plates of bacterial colonies formed by E. coli and S. aureus in the presence of GO@P-g-C3N4-80% after different irradiation times
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图 14 GO@P-g-C3N4-80%在3次循环过程中对E. coli和S. aureus的光催化抑菌率
Figure 14. Photocatalytic inhibition rates of E. coli and S. aureus by GO@P-g-C3N4-80% during the three cycles
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图 15 GO@P-g-C3N4-80%在3次循环过程中的E. coli和S. aureus菌落琼脂平板照片
Figure 15. Images of the agar plates of bacterial colonies formed by E. coli and S. aureus in the presence of GO@P-g-C3N4-80% during the three cycles
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图 16 GO@P-g-C3N4-80%三次循环后的XRD图谱
Figure 16. XRD patterns of GO@P-g-C3N4-80% after third cycles
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图 17 S. aureus ((a)~(d))和E. coli ((a*)~(d*))在GO@P-g-C3N4-80%的催化下分别照射不同时间后的SEM图像
Figure 17. SEM images of S. aureus ((a)-(d)) and E. coli ((a*)-(d*)) after irradiation for different times under the catalysis of GO@P-g-C3N4-80%
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图 18 P-g-C3N4和GO@P-g-C3N4在黑暗条件下(a)和光照5 min后(b)的DMPO-•O−2 ESR谱；GO@P-g-C3N4在黑暗条件下和光照5 min后的DMPO-•OH ESR谱(c) 和TEMPO-e− ESR谱(d)
Figure 18. ESR spectra of DMPO−•O−2 over P-g-C3N4 and GO@P-g-C3N4 under irradiation times of 0 min (a) and 5 min (b); ESR spectra of DMPO-•OH (c) and TEMPO-e− (d) with GO@P-g-C3N4 under irradiation times of 0 min and 5 min
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图 19 GO@P-g-C3N4在可见光照射下的抗菌示意图
Figure 19. Schematic representation of the antibacterial properties of the GO@P-g-C3N4 under irradiation with visible light
表 1 样品名称及制备过程氧化石墨烯(GO)与质子化石墨相氮化碳(P-g-C3N4)的质量比
Table 1 Samples and the mass ratios of the preparation process graphene oxide (GO) to protonated graphite carbon nitride (P-g-C3N4)
Sample GO ∶ P-g-C3N4 GO@P-g-C3N4-70% 3 ∶ 7 GO@P-g-C3N4-80% 1 ∶ 4 GO@P-g-C3N4-90% 1 ∶ 9 
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其他相关附件
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目的
光催化抗菌是一种安全环保且高效的抗菌方式，为获得性能更加优异的光催化材料用于消杀细菌，以减少有害细菌导致的环境污染，本文利用带正电荷的质子化石墨相氮化碳(P-g-CN)与带负电荷的氧化石墨烯(GO)之间的静电吸引，成功制备了具有2D/2D异质结构的GO@P-g-CN复合材料，研究其光催化抗菌性能及抗菌机理。
方法通过静电自组装法制备了P-g-CN涂层的GO复合材料(GO@P-g-CN)。以尿素为原料，合成黄色块状g-CN(B-g-CN)；对B-g-CN进行酸化处理和超声剥离，得到P-g-CN；将P-g-CN分散液逐滴添加到GO溶液中，搅拌生成絮状沉淀后，放至冷冻干燥机中，得到干燥的粉末即GO@P-g-CN复合材料。采用SEM、TEM、XRD、XPS、Raman、BET测试等对其进行形貌与结构的表征；通过紫外-可见漫反射光谱(UV-Vis DRS)、光致发光(PL)发射光谱、瞬时光电流响应测试分析其光学特性；通过抗菌实验和抗菌循环实验分析光催化剂的抗菌性和稳定性，结合光照不同时间段下和的SEM图以及电子顺磁共振波谱(ESR)表征对GO@P-g-CN光催化复合材料的光催化机制进行探究。
结果形貌与结构表征显示GO@P-g-CN复合材料的形貌兼顾了P-g-CN的二维薄层结构和GO的绸缎状，具有良好的2D/2D接触界面；GO@P-g-CN的XRD谱图中观察到GO在2θ=11.5°处的特征峰以及位于27.6°的尖锐和增强的强度峰表明结晶度增强，与P-g-CN相比，GO和P-g-CN复合后可能强化了层间结构，没有发现其他杂质峰，表明制备的催化剂纯度较高；XPS分析说明质子化对g-CN的基本构型影响不大，与GO结合后，没有新的化学键或官能团生成；Raman谱图表明GO@P-g-CN复合材料缺陷减少、有序度提高，电子容易传导；BET测试表明，加入GO后，P-g-CN与GO@P-g-CN峰值位置不变，复合材料的比表面积和孔体积增大，即GO加入后，孔隙未被堵塞。光电化学性质分析可知，由UV-Vis DRS图谱计算得到P-g-CN的带隙为2.76 eV，而GO@P-g-CN的带隙为2.63 eV；PL谱图证实了GO@P-g-CN峰强度明显低于P-g-CN，即GO@P-g-CN具有更高的载流子分离效率；瞬态光电流响应发现GO@P-g-CN的光电流密度高于P-g-CN，即GO的加入可以赋予复合材料高效的电子转移能力，可有效分离光生电子和空穴，增强了复合材料的光催化活性。对GO@P-g-CN复合材料进行光催化抗菌性能测试，光照150 min后，GO与P-g-CN对和的抑菌率分别为66.44%、95.17%和77.92%、87.39%，GO@P-g-CN对和的抑菌率均达到99%以上，明显优于GO与P-g-CN，三次循环后对和的抑菌率仍有95.53%和93.42%。ESR谱图分析证实了GO@P-g-CN在光催化过程中能产生·O和·OH、e，且与P-g-CN相比，GO的加入可以抑制电子空穴对的复合，使体系中更多O被电子还原生成·O，增强GO@P-g-CN复合材料的光催化活性，使和在活性自由基的作用下，细胞膜破裂，导致细菌死亡。
结论通过静电自组装法制备的具有2D/2D异质结构的 GO@P-g-CN复合材料，具有高效的电子转移能力，可有效分离光生电子和空穴，从而增强了复合材料的光催化活性。光催化抗菌实验表明，光照150 min后，对和的抑菌率均达到99%以上，3次循环后抑菌率仍有95.53%和93.42%，循环后复合材料晶体结构没有明显变化，具有良好的性能稳定性和结构稳定性。
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石墨相氮化碳光催化材料，由碳和氮以sp2杂化形成π共轭平面，具有类似石墨的结构和三-s-三嗪构造单元，带隙(约2.7 eV)较窄，具有低成本、稳定性好、生态友好等优点，在光催化降解有机污染物、抗菌、光催化产氢等领域得到了广泛应用。但是g-C3N4对可见光吸收率低、光生e−/h+对易快速重组，单独使用g-C3N4表现出的光催化效率并不理想，限制了其发展应用。
本文首先对石墨相氮化碳质子化处理，通过静电自组装法与带负电的氧化石墨烯复合，成功制备了具有2D/2D异质结构的GO@P-g-C3N4复合材料。P-g-C3N4的质子化增加了活性表面积和光生e−/h+对产率，加入GO冻干处理后，GO@P-g-C3N4复合材料保留了大量羟基/羧基，不仅增大了复合材料的比表面积(87.5 m2/g)和孔体积(0.676 m3/g)，使细菌与光催化剂接触面积增加，而且降低了GO表面氧的吸附能，从而产生更强的氧自由基。光电性能测试分析表明，GO@P-g-C3N4复合材料对可见光的吸收范围拓宽，载流子密度增大，光生电子空穴对的复合率降低，GO@P-g-C3N4复合材料的光催化活性有效提高。光催化抗菌实验表明，GO与P-g-C3N4以质量比为1∶4合成的GO@P-g-C3N4-80%复合材料，光照100 min后，对E. coli和S. aureus的抑菌率分别为98.80%和95.99%；光照150 min后，对E. coli和S. aureus的抑菌率均达到99%以上。
(a) 对照组和不同光催化剂对E. coli和S. aureus的抑菌率(光照150 min)和(b) GO@P-g-C3N4-80%在不同光照时间下对E. coli和S. aureus的抑菌率
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