Preparation and photocatalytic performance of carbon dots/g-C3N4 composite catalyst
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摘要: g-C3N4的光吸收和光生载流子的复合问题是限制其高效光催化应用的关键问题，为此本文以煤沥青为前驱体合成碳点(CDs)，然后采用超声辅助法制备了CDs/g-C3N4复合催化剂。通过TEM、XRD、UV-Vis漫反射光谱、PL光谱、EIS测试和光电流响应测试等表征了催化剂的结构和光学、光电性能。结果表明，CDs引入后能带结构的调控和界面的形成，拓展了复合光催化剂的光吸收范围，促进了光生电子和空穴的有效分离和迁移，从而有利于光催化反应的进行。以罗丹明B (RhB)为模型反应，在可见光照射下，CDs/g-C3N4复合催化剂的光催化活性明显高于纯g-C3N4，在40 min内就可以实现98.6%的RhB降解率，其降解速率常数是纯g-C3N4的6.8倍。活性物种捕获实验表明，降解体系中起主要作用的是•O2−。同时CDs/g-C3N4复合催化剂具有良好的稳定性，5次循环反应后，RhB的降解率仍达到97.5%，展示了其在可见光光催化方面较好的应用前景。Abstract: The light absorption and photo-induced carrier recombination of g-C3N4 are the key problems that limit its efficient photocatalytic applications. Herein, carbon dots (CDs) were synthesized using coal pitch as precursor and then the CDs/g-C3N4 composite catalyst was prepared by ultrasonic-assisted method. The structure, optical and photoelectrochemical properties of the catalyst were characterized by TEM, XRD, UV-Vis diffuse reflection spectrum, PL spectrum, EIS test and photocurrent response test. The results show that the regulation of band structure and the formation of interface after the introduction of CDs expand the range of light absorption of the composite photocatalyst, promote the effective separation and migration of photogenerated electrons and holes, and thus facilitate the photocatalytic reaction. Using rhodamine B (RhB) as the model, the photocatalytic activity of CDs/g-C3N4 composite catalyst is significantly higher than that of pure g-C3N4 under visible light irradiation. The degradation rate of RhB can reach 98.6% within 40 min, and the degradation rate constant of CDs/g-C3N4 is 6.8 times that of g-C3N4. The capture of experiment of active species reveals that •O2− plays a major role in the degradation system. In addition, CDs/g-C3N4 composite catalyst exhibit good stability. After 5 cycles, the degradation rate of RhB is still up to 97.5%, which shows a good application prospect in visible light photocatalysis.
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Key words:
- photocatalysis /
- g-C3N4 /
- carbon dots /
- composite catalyst /
- rhodamine B /
- degradation
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图 1 g-C3N4和碳点(CDs)/g-C3N4复合催化剂的XRD图谱
Figure 1. XRD patterns of g-C3N4 and carbon dots (CDs)/g-C3N4 composite catalyst
图 2 CDs的TEM图像(a)和尺寸分布(b)；CDs/g-C3N4复合催化剂的TEM图像((c)、(d))
Figure 2. TEM image (a) and diameter distribution (b) of CDs; TEM images of CDs/g-C3N4 composite catalyst ((c), (d))
图 4 g-C3N4和CDs/g-C3N4复合催化剂的UV-Vis漫反射光谱图(a)和带隙图(b)
Figure 4. UV-Vis diffuse reflection spectra (a) and bandgap diagram (b) of g-C3N4 and CDs/g-C3N4 composite catalyst
α—Absorption coefficient; h—Planck constant; ν—Frequency
图 5 g-C3N4和CDs/g-C3N4复合催化剂光催化降解罗丹明B (RhB)性能
Figure 5. Photocatalytic degradation performance of rhodamine B (RhB) by g-C3N4 and CDs/g-C3N4 composite catalyst
C/C0—Ratio of the concentration of RhB at different tiome to the initial concentration of RhB
图 6 CDs/g-C3N4复合催化剂不同用量下的光催化降解RhB性能(a)和光催化降解RhB反应动力学(b)
Figure 6. Photocatalytic degradation performance of RhB with different amount of CDs/g-C3N4 composite catalyst (a) and kinetics of RhB photocatalytic degradation (b)
K—Apparent rate constant
图 7 CDs/g-C3N4 复合催化剂光催化降解RhB循环稳定性
Figure 7. Restability for photocatalytic degradation of RhB by CDs/g-C3N4 composite catalyst
图 8 CDs/g-C3N4 复合催化剂反应前后XRD图谱
Figure 8. XRD patterns of fresh and used CDs/g-C3N4 composite catalyst
图 9 g-C3N4和CDs/g-C3N4复合催化剂的PL图谱
Figure 9. PL spectra of g-C3N4 and CDs/g-C3N4 composite catalyst
图 10 CDs、g-C3N4和CDs/g-C3N4复合催化剂的电化学阻抗谱
Figure 10. Electrochemical impedance spectroscopy of CDs, g-C3N4 and CDs/g-C3N4 composite catalyst
图 11 CDs、g-C3N4和CDs/g-C3N4复合催化剂的光电流-时间曲线
Figure 11. Photocurrent-time curves of CDs, g-C3N4 and CDs/g-C3N4 composite catalyst
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[1] KUDO A, MISEKI Y. Heterogeneous photocatalyst materials for water splitting[J]. Chemical Society Reviews,2009,38(1):253-278. doi: 10.1039/B800489G [2] YAN P C, JI F W, ZHANG W, et al. Engineering surface bromination in carbon nitride for efficient CO2 photoconversion to CH4[J]. Journal of Colloid and Interface Science,2023,634:1005-1013. doi: 10.1016/j.jcis.2022.12.063 [3] GUAN G W, ZHENG S T, XIA M Y, et al. Incorporating CdS and anchoring Pt single atoms into porphyrinic metal-organic frameworks for superior visible-light and sunlight-driven H2 evolution[J]. Chemical Engineering Journal,2023,464:142530. doi: 10.1016/j.cej.2023.142530 [4] CAO Z, ZHAO Y P, LI J M, et al. Rapid electron transfer-promoted tetracycline hydrochloride degradation: Enhanced activity in visible light-coupled peroxymonosulfate with PdO/g-C3N4/kaolinite catalyst[J]. Chemical Engineering Journal,2023,457:141191. doi: 10.1016/j.cej.2022.141191 [5] CAO S W, LOW J X, YU J G, et al. Polymeric photocatalysts based on graphitic carbon nitride[J]. Advanced Materials,2015,27(13):2150-2176. doi: 10.1002/adma.201500033 [6] HE F, WANG Z X, LI Y X, et al. The nonmetal modulation of composition and morphology of g-C3N4-based photocatalysts[J]. Applied Catalysis B: Environmental,2020,269:118828. doi: 10.1016/j.apcatb.2020.118828 [7] FANG Y X, HOU Y D, FU X Z, et al. Semiconducting polymers for oxygen evolution reaction under light illumination[J]. Chemical Society Reviews,2022,122(3):4204-4256. doi: 10.1021/acs.chemrev.1c00686 [8] YANG M C, LIAN R H, ZHANG X R, et al. Photocatalytic cyclization of nitrogen-centered radicals with carbon nitride through promoting substrate/catalyst interaction[J]. Nature Communications,2022,13(1):4900-4909. doi: 10.1038/s41467-022-32623-3 [9] MING H B, ZHANG P Y, YANG Y, et al. Tailored poly-heptazine units in carbon nitride for activating peroxymonosulfate to degrade organic contaminants with visible light[J]. Applied Catalysis B: Environmental,2022,311:121341. doi: 10.1016/j.apcatb.2022.121341 [10] GAO Y, LIN J Y, ZHANG Q Z, et al. Facile synthesis of heterostructured YVO4/g-C3N4/Ag photocatalysts with enhanced visible-light photocatalytic performance[J]. Applied Catalysis B: Environmental,2018,224:586-593. doi: 10.1016/j.apcatb.2017.11.003 [11] 吴健博, 石亮, 郑小强, 等. g-C3N4/BiOCl 复合光催化剂作为2D/2D异质结用于光催化降解染料性能研究[J]. 复合材料学报, 2023, 40(1):323-333.WU Jianbo, SHI Liang, ZHENG Xiaoqiang, et al. g-C3N4/BiOCl composite photocatalyst used as 2D/2D heterojunction for photocatalytic degradation of dyes[J]. Acta Materiae Compositae Sinica,2023,40(1):323-333(in Chinese). [12] TANG C S, CHENG M, LAI C, et al. Recent progress in the applications of non-metal modified graphitic carbon nitride in photocatalysis[J]. Coordination Chemistry Reviews,2023,474:214846. doi: 10.1016/j.ccr.2022.214846 [13] 梁家驰, 李昕奇, 左建良, 等. 石墨相氮化碳形貌调控及其光催化性能研究[J]. 化工新型材料, 2022, 50(8):223-228.LIANG Jiachi, LI Xinqi, ZUO Jianliang, et al. Morphology control of g-C3N4 with improved photocatalytic performance[J]. New Chemical Materials,2022,50(8):223-228(in Chinese). [14] 郑富凯, 李宗霖, 曹煜祺, 等. 钴、碳共掺杂氮化碳的制备及其光催化分解水产氢性能[J]. 无机化学学报, 2021, 37(11):2029-2036. doi: 10.11862/CJIC.2021.226ZHENG Fukai, LI Zonglin, CAO Yuqi, et al. Cobalt and carbon co-doped carbon nitride for enhanced photocatalytic hydrogen evolution[J]. Chinese Journal of Inorganic Chemistry,2021,37(11):2029-2036(in Chinese). doi: 10.11862/CJIC.2021.226 [15] SARAEV A A, KURENKOVA A Y, ZHURENOK A V, et al. Selectivity control of CO2 reduction over Pt/g-C3N4 photocatalysts under visible light[J]. Catalysts,2023,13(2):273-287. doi: 10.3390/catal13020273 [16] WON J H, KIM M K, OH H S, et al. Scalable production of visible light photocatalysts with extended nanojunctions of WO3/g-C3N4 using zeta potential and phase control in sol-gel process[J]. Applied Surface Science,2023,612:155838. doi: 10.1016/j.apsusc.2022.155838 [17] FU J W, YU J G, JIANG C J, et al. g-C3N4-based heterostructured photocatalysts[J]. Advanced Energy Materials,2018,8(3):1701503. doi: 10.1002/aenm.201701503 [18] 车望远, 刘长军, 杨焜, 等. 荧光碳点的制备和性质及其应用研究进展[J]. 复合材料学报, 2016, 33(3):431-450. doi: 10.13801/j.cnki.fhclxb.20160219.001CHE Wangyuan, LIU Changjun, YANG Kun, et al. Research progress in preparation, property and applications of fluorescent carbon dots[J]. Acta Materiae Compositae Sinica,2016,33(3):431-450(in Chinese). doi: 10.13801/j.cnki.fhclxb.20160219.001 [19] CAI T T, LIU B, PANG E N, et al. A review on the preparation and applications of coal-based fluorescent carbon dots[J]. New Carbon Materials,2020,35(6):646-666. doi: 10.1016/S1872-5805(20)60520-0 [20] ZHAO Z X, REISCHAUER S, PIEBER B, et al. Carbon dot/TiO2 nanocomposites as photocatalysts for metallaphotocatalytic carbon-heteroatom cross-couplings[J]. Green Chemistry,2021,23(12):4524-4530. doi: 10.1039/D1GC01284C [21] REN Y Q, HAO C H, CHANG Q, et al. Boosting chemoselective reduction of 4-nitrostyrene via photoinduced energetic electrons from in situ formed Cu nanoparticles on carbon dots[J]. Green Chemistry,2021,23(8):2938-2943. doi: 10.1039/D1GC00409C [22] HU S L, ZHANG W J, LI N, et al. Integrating biphase γ- and α-Fe2O3 with carbon dots as a synergistic nanozyme with easy recycle and high catalytic activity[J]. Applied Surface Science,2021,545:148987. doi: 10.1016/j.apsusc.2021.148987 [23] CAI T T, CHANG Q, LIU B, et al. Triggering photocatalytic activity of carbon dot-based nanocomposites by a self-supplying peroxide[J]. Journal of Materials Chemistry A,2021,9(14):8991-8997. doi: 10.1039/D1TA01097B [24] LI S J, PANG E N, LI N, et al. High reaction activity enables carbon dots to construct multicomponent nanocomposites with superior catalytic performance[J]. Inorganic Chemistry Frontiers,2022,9(8):1761-1769. doi: 10.1039/D2QI00260D [25] LIU W, LI Y Y, LIU F Y, et al. Visible-light-driven photocatalytic degradation of diclofenac by carbon quantum dots modified porous g-C3N4: Mechanisms, degradation pathway and DFT calculation[J]. Water Research,2019,151:8-19. doi: 10.1016/j.watres.2018.11.084 [26] LIANG J N, YANG X H, FU H T, et al. Integrating optimal amount of carbon dots in g-C3N4 for enhanced visible light photocatalytic H2 evolution[J]. International Journal of Hydrogen Energy,2022,47(41):18032-18043. doi: 10.1016/j.ijhydene.2022.03.285 [27] WANG G, LI X, HAO P C, et al. g-C3N4/nitrogen-doped carbon dot/silver nanoparticle-based ternary photocatalyst for water pollutant treatment[J]. ACS Applied Nano Materials,2023,6(7):5747-5758. doi: 10.1021/acsanm.3c00185 [28] WANG J, GAO M M, HO G W. Bidentate-complex-derived TiO2/carbon dot photocatalysts: In situ synthesis, versatile heterostructures, and enhanced H2 evolution[J]. Journal of Materials Chemistry A,2014,2(16):5703-5709. doi: 10.1039/c3ta15114j [29] YOU Z Y, LI G, WANG C H, et al. The synergistic effect of potassium ions and nitrogen defects on carbon nitride for enhanced photocatalytic hydrogen evolution[J]. International Journal of Hydrogen Energy,2023,48(42):15934-15943. doi: 10.1016/j.ijhydene.2023.01.089 [30] ZHENG Y M, LUO Y, RUAN Q S, et al. Plasma-induced hierarchical amorphous carbon nitride nanostructure with two N2 C-site vacancies for photocatalytic H2O2 production[J]. Applied Catalysis B: Environmental,2022,311:121372. doi: 10.1016/j.apcatb.2022.121372 -
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