English

• Advanced oxidation processes (AOPs), with advantages of high efficiency, universality and thoroughness oxidation on organic pollutants, have become one of the promising approaches for refractory organic wastewater treatment [1-6]. As one of the most mature and diverse strategies, transition metal-based Fenton-like catalysis have been studied extensively, such reactions require no additional energy and overcome the problems of homogeneous reactions [7-11]. To achieve the highly efficient generation of reactive oxygen species, many strategies are mainly focused on tailoring transition metal-based catalysts with desired active sites generation and exposure by controlling crystal facet growth and engineering geometry structural [12-17]. These traditional strategies are always conducted in the wet conduction, which needs the solvents such as water, ethanol or ethylene glycol [18,19]. Tedious multistep processes and harsh reaction conditions blocked the practical applications of these technologies [20-24]. Therefore, developing a facile scale-up method to create more active sites to boost transition metal-based catalysts performance still remains a major challenge.

  Notably, inducing chemical defects have emerged as a promising approach for improving catalytic performance by modulating the electronic structure of transition metal-based catalysts [25-28] and solid-state synthesis method with effectively introduce defects make it easy to scale-up production [29-32]. Hence, we develop a one-step all solid-state growth strategy to precisely engineer oxygen defects in V₂O₅ that are self-assembled during the process of selective crystallization, thereby boosting the Fenton-like performance in defective V₂O₅@graphene/H₂O₂ system (0.2012 min⁻¹), which was 14.3, 28.2, and 17.3 times higher than that of graphene/H₂O₂ (0.0085 min⁻¹), pure V₂O₅/H₂O₂ (0.0043 min⁻¹) and mechanical mixed system (graphene+V₂O₅/H₂O₂ 0.0070 min⁻¹), respectively. Additionally, O_Vs-riched V₂O₅@graphene exhibits an outstanding catalytic stability and degradation ability for a variety of refractory organic pollutants. Our work provides a promising synthetic strategy for transition metals in Fenton-like catalytic degradation process to produce reactive oxygen species, paving the way for sustainable water purification and material design optimization.

  The graphene-controlled thermal decomposition reaction of VCl₃ to defective V₂O₅@graphene by an in situ one-step, all-solid-state synthesis was showed in Fig. 1a. XRD patterns indicated that as the graphene addition was below 50%, VCl₃ was mainly transformed to V₂O₅ at 400 ℃ for 120 min and increasing graphene can induce the further decomposition of V₂O₅ to V₂O₄ (Fig. 1b and Fig. S1 in Supporting information) [33,34]. The surface morphologies of defective V₂O₅@graphene composites were obtained by field-emission scanning electron microscopy (FESEM), which showed that V₂O₅ crystals were clearly observed on the graphene sheets (Fig. 1c). Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) associated with the fast Fourier transform (FFT) showed a series clear lattice fringes of 2.501 Å, 2.143 Å, 2.250 Å and 2.076 Å corresponding to the (121), (012), (131) and (022) planes of V₂O₅, thereby confirming the formation of V₂O₅ crystals on graphene surface (Figs. 1d–g, Figs. S2 and S3 in Supporting information). What is more, the magnified image in Fig. 1e clearly displayed that many dislocations and distortions (red circle) were distributed around the lattice fringes, which suggested that defective V₂O₅@graphene has a typical defect-rich structure. The X-ray photoelectron spectroscopy (XPS) analysis of V₂O₅ and V₂O₅@graphene was investigated. With the graphene regulation, the new peaks of 531.0 eV and 532.8 eV corresponding to O_Vs and -OH bonds were obtained in defective V₂O₅@graphene (Fig. S4 in Supporting information), which was absent in pure V₂O₅, thereby confirming the formation of O_Vs in V₂O₅@graphene.

  Figure 1

  

  Figure 1.  (a) Schematic illustration of the sample synthesis process. (b) XRD pattern of annealed VCl₃-graphene at different mass proportions. (c) SEM and magnified SEM image of defective V₂O₅@graphene. (d, e) TEM and HRTEM image of defective V₂O₅@graphene. (f) The associated FFT analysis taken from the regions outlined in (e). (g) Elemental mapping images of defective V₂O₅@graphene.

  DownLoad: Full-Size Img PowerPoint

  Energy dispersive spectroscopy (EDS) analysis revealed that the molar ratio of V/O in defective V₂O₅@graphene, V₂O₄@graphene and pure V₂O₅ was 1:0.956, 1:1.487 and 2.128 (Table S1 in Supporting information), respectively, implying that the V atom content of defective V₂O₅@graphene was higher than that of pure V₂O₅, thereby confirming the O_Vs introduction in defective V₂O₅@graphene [35].

  To better reveal the positive effect of O_Vs on Fenton-like performance, degradation experiments with Rhodamine B (RhB, 10 mg/L) as a model dye were conducted. Fig. 2a showed that RhB cannot be decoloured in the presence of only H₂O₂ or defective V₂O₅@graphene. With both defective V₂O₅@graphene and H₂O₂ addition, the degradation of RhB was extremely active and conformed to quasi-first-order kinetics, and the reaction rate constant (k_obs) was 0.1214 min⁻¹, which was much higher than that of graphene/H₂O₂ (0.0085 min⁻¹), pure V₂O₅/H₂O₂ (0.0043 min⁻¹) and mechanical mixed system (graphene+V₂O₅/H₂O₂, 0.0070 min⁻¹), respectively (Fig. 2b). The H₂O₂ dosages and solution pH values had an enormous effect on H₂O₂ activation and their influences on the RhB degradation efficiency were studied. To confirm the optimum addition of H₂O₂, the catalytic performance of V₂O₅@graphene/H₂O₂ system with different H₂O₂ addition was investigated and there was no major breakthrough in Fenton-like activity as H₂O₂ usage increasing to 200 µL (Fig. S5 in Supporting information). Thus the optimal 30 wt% H₂O₂ usage was selected as 200 µL. Notably, we found that defective V₂O₅@graphene had better catalytic activity under acidic and weak alkaline (pH range: 3–9, Fig. S6 in Supporting information). Under the optimal conditions, defective V₂O₅@graphene exhibits the highest intrinsic activity, which surpassed the most advanced heterogeneous catalysts (Fig. 2c and Table S2 in Supporting information). These findings demonstrated that graphene-controlled VCl₃ thermal decomposition can in situ induced O_Vs in V₂O₅@graphene, which boosts Fenton-like performance for efficient complex organic wastewater treatment.

  Figure 2

  

  Figure 2.  (a) The degradation of RhB in pure graphene/H₂O₂, V₂O₅@graphene/H₂O_2, V₂O₅@graphene, graphene+V₂O₅/H₂O₂ and pure V₂O₅/H₂O₂ reaction systems. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [RhB] = 10 mg/L and pH 7.0. (b) Corresponding kinetic curves of the different catalytic systems. (c) Comparison of k_obs of different pollutant degradation via Fenton-like oxidation in this work and the previous reports (details in Table S2 in Supporting information). (d) Mineralization efficiency of different pollutants including RhB (10 mg/L), MB (20 mg/L), MR (20 mg/L), BPA (20 mg/L) and TCP (10 mg/L) within 4 h. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt% and pH 7.0.

  DownLoad: Full-Size Img PowerPoint

  For the practical applications of defective V₂O₅@graphene/H₂O₂ system, we assessed the removal efficiency of methylene blue (MB), methyl red (MR), bisphenol A (BPA) and 2,4,6-trichlorophenol (TCP) which were universally discovered at acidic or weak alkaline environments. Fig. 2d showed that the TOC removal efficiency of RhB, MB, MR, BPA, and TCP reach up to 100%, 99.9%, 96.9%, 99.8%, and 99.6% within 6 h, confirming the excellent mineralization ability for persistent organic pollutants. In addition, catalyst stability was also tested and defective V₂O₅@graphene indicated that the defective V₂O₅@graphene/H₂O₂ system remained a high Fenton-like activity even after 12 cycles (Fig. S7 in Supporting information). During the cycle experiment, the leaching amount of V ions was investigated via inductively coupled plasma (ICP) and Fig. S8 (Supporting information) showed a low V ions concentration after each cycle (0.553, 0.573, 0.585 and 0.602 mg/L), confirming the stability of defects V₂O₅@graphene in Fenton-like system. Remarkably, no significant morphological changes were observed in TEM and HRTEM images (Fig. S9 in Supporting information). The XRD patterns of defective V₂O₅@graphene before and after reaction were basically identical, demonstrating that the structure was stable (Fig. S10 in Supporting information). What is more, Fig. S11 (Supporting information) showed that the removal efficiency of BPA was achieved higher than 90.0% within 60 min even in the presence of NaCl, Na₂SO₄ and Na₂CO₃, suggesting that such defective V₂O₅@graphene/H₂O₂ system provides an effective way for saline organic wastewater treatment. These results inferred that defective V₂O₅@graphene with outstanding H₂O₂ activation and stability would be a bright Fenton-like catalyst for removing environmental organic pollutants.

  On the basis of the above observations, in situ introduction of O_Vs in defective V₂O₅@graphene plays an important role for Fenton-like performance and the enhanced mechanism of defective V₂O₅@graphene was proposed as shown in Fig. 3a. Besides the redox cycle of V⁴⁺/V⁵⁺ in defective V₂O₅@graphene for H₂O₂ activation, the O_Vs of electron-donor nature can not only active H₂O₂ for the ^•OH generation, but also facilitate the reduction of V⁵⁺ to V⁴⁺, thereby boosting the Fenton-like performance in defective V₂O₅@graphene/H₂O₂ system (Fig. 3a). This result was consistent with the previous research that the primary process of generating ^•OH was the single electron transfer from surface V⁴⁺ to H₂O₂ (Eq. 1), and a chain reaction can be propagated as V⁴⁺ can be regenerated via H₂O₂ (Eq. 2) [36].

  (1)

  (2)

  Figure 3

  

  Figure 3.  (a) Schematic illustration of the Fenton-like catalysis mechanism via defective V₂O₅@graphene/H₂O₂ system. (b) EPR spectra of DMPO adducts in V₂O₅@graphene/H₂O₂, pure H₂O₂, pure graphene/H₂O₂, pure V₂O₅/H₂O₂ and V₂O₅@graphene reaction systems. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [DMPO] = 100 mmol/L, and pH 7.0. (c) High-resolution XPS spectrum of V 2p and O 1s of defective V₂O₅@graphene and pure V₂O₅ fresh and used. (d) The quenching experiments with existence of 1 mmol/L CH₃OH, 10 mmol/L CH₃OH in the defective V₂O₅@graphene/H₂O₂ catalytic system. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [RhB] = 10 mg/L and pH 7.0.

  DownLoad: Full-Size Img PowerPoint

  The presence of O_Vs can maintain the electrostatic equilibrium, which facilitates the absorption of a large number of oxygen species, thereby promoting catalytic oxidation reactions and radical reactions [37]. Additionally, towards the oxides with surface O_Vs, interaction mode between O_Vs and H₂O₂ was a novel but overlooked reaction way for the H₂O₂ activation (Eq. 3) [38].

  (3)

  The electron paramagnetic resonance (EPR) analysis showed that DMPO−OH (1:2:2:1) signals produced in defective V₂O₅@graphene/H₂O₂ system was much higher than that in systems of pure H₂O₂, V₂O₅/H₂O₂ and graphene+V₂O₅/H₂O₂, which demonstrated the positive effect for H₂O₂ activation with the help of O_Vs (Fig. 3b).

  To better insight into this mechanism, we used XPS analysis to analyze chemical state of catalysts before and after reaction (Fig. 3c). Two peaks located at 517.3 eV and 515.8 eV in the V 2p_3/2 XPS spectra of pristine V₂O₅ and V₂O₅@graphene were assigned to the V⁵⁺ and V⁴⁺ signals, respectively. After Fenton-like reaction, the peak intensity of surface -OH groups (532.8 eV) were improved significantly, which was attributed to the H₂O₂ activation by O_Vs in V₂O₅@graphene [38,39]. Interestingly, the molar ratio of V⁵⁺/V⁴⁺ in V₂O₅@graphene before and after reaction was 1.27:1 and 1.80:1, while the increase amount of V⁵⁺ was much lower than that of pure V₂O₅ before and after reaction (3.51:1 and 5.71:1), suggesting that the electron-rich O_Vs can suppress high value vanadium (V⁵⁺) formation. Therefore, defective V₂O₅@graphene with rich O_Vs ensures the high efficiency and stable for Fenton-like catalysis. In addition, to determine the source of the electrons, we fabricated the V₂O₅@graphite, V₂O₅@CNT, and V₂O₅@graphene through the solid phase synthesis method. Interestingly, the catalytic performance of V₂O₅@graphene was much higher than that of V₂O₅@graphite and V₂O₅@CNT (Fig. S12 in Supporting information), which demonstrated that the formed electron-rich O_Vs gives electron to accelerate the high value vanadium (V⁵⁺) reduction. The H₂O₂ activation performance of defective V₂O₅@graphene and pure V₂O₅ was independent of the BET surface areas of the catalysts (Table S3 and Figs. S13a-d in Supporting information), indicating that the binding capacity of the catalysts with H₂O₂ was mainly related to their chemical structure. The radical quenching experiments were further conducted to explored the roles of the reactive species in pollutant degradation. The different concentrations of methanol (^•OH scavengers [40,41]) addition significantly inhibited the RhB degradation, which suggested that the ^•OH-radical pathways dominated the RhB degradation in the V₂O₅/H₂O₂ catalytic system (Fig. 3d).

  In summary, the vacancy defective V₂O₅@graphene with rich O_Vs was successfully prepared by solid phase synthesis method. Defective V₂O₅@graphene provides sufficient O_Vs, which can not only active H₂O₂ for the ^•OH generation, but also accelerate the electron transfer from V⁵⁺ to V⁴⁺, which make defective V₂O₅@graphene a bright Fenton-like catalyst for removing environmental organic pollutants. The defective V₂O₅@graphene/H₂O₂ system presents outstanding activity and stability for ^•OH generation, which can degrade organic pollutants efficiently.

  Declaration of competing interest

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  Acknowledgments

  This work was supported by the National Key R&D Program of China (No. 2019YFC1803900), the National Natural Science Foundation of China (Nos. U1932123, 22073069, 21773082, and 42107402), the National Science Fund for Outstanding Young Scholars (No. 11722548), and the University of Chinese Academy of Sciences (No. WIUCASOD2021014).

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2024.109833.

  
  
• 1. [1]

     F. Yang, B. Sheng, Z. Wang, et al., J. Hazard. Mater. 406 (2021) 124774. doi: 10.1016/j.jhazmat.2020.124774

  2. [2]

     V. Sarria, M. Deront, P. Péringer, C. Pulgarin, Appl. Catal. B: Environ. 40 (2003) 231–246. doi: 10.1016/S0926-3373(02)00162-5

  3. [3]

     J.L. Wang, L.J. Xu, Cri. Rev. Environ. Sci. Technol. 42 (2012) 251–325. doi: 10.1080/10643389.2010.507698

  4. [4]

     Z.H. Xie, C.S. He, D.N. Pei, et al., Chem. Eng. J. 468 (2023) 143778. doi: 10.1016/j.cej.2023.143778

  5. [5]

     S. Feijoo, X. Yu, M. Kamali, L. Appels, R. Dewil, Rev. Environ. Sci. Biotechnol. 22 (2023) 205–248. doi: 10.1007/s11157-023-09645-4

  6. [6]

     H. Weng, Y. Yang, C. Zhang, et al., Chem. Eng. J. 453 (2023) 139812. doi: 10.1016/j.cej.2022.139812

  7. [7]

     L. Gu, N. Zhu, L. Wang, X. Bing, X. Chen, J. Hazard. Mater. 198 (2011) 232–240. doi: 10.1016/j.jhazmat.2011.10.035

  8. [8]

     M. Gągol, A. Przyjazny, G. Boczkaj, Chem. Eng. J. 338 (2018) 599–627. doi: 10.1016/j.cej.2018.01.049

  9. [9]

     F. Mo, C. Song, Q. Zhou, et al., Proc. Natl. Acad. Sci. U. S. A. 120 (2023) e2300281120. doi: 10.1073/pnas.2300281120

  10. [10]

      Y. Li, J. Xu, G. Shi, D. Yue, Chem. Commun. 59 (2023) 1341–1344. doi: 10.1039/D2CC05989D

  11. [11]

      D. Yue, X. Yan, C. Guo, X. Qian, Y. Zhao, J. Phys. Chem. Lett. 11 (2020) 968–973. doi: 10.1021/acs.jpclett.9b03597

  12. [12]

      Y. Xue, Q. Sui, M.L. Brusseau, et al., Chem. Eng. J. 353 (2018) 657–665. doi: 10.1016/j.cej.2018.07.124

  13. [13]

      P. Salgado, V. Melin, M. Albornoz, H, et al., Appl. Catal. B: Environ. 226 (2018) 93–102. doi: 10.1016/j.apcatb.2017.12.035

  14. [14]

      Q. Yi, J. Ji, B. Shen, et al., Environ. Sci. Technol. 53 (2019) 9725–9733. doi: 10.1021/acs.est.9b01676

  15. [15]

      D. Yue, C. Guo, X. Yan, et al., Chem. Eng. J. 360 (2019) 97–103. doi: 10.1016/j.cej.2018.11.201

  16. [16]

      D.Q. He, Y.J. Zhang, D.N. Pei, et al., J. Hazard. Mater. 382 (2020) 121090. doi: 10.1016/j.jhazmat.2019.121090

  17. [17]

      Q. Ji, L. Bi, J. Zhang, H. Cao, X.S. Zhao, Energy Environ. Sci. 13 (2020) 1408–1428. doi: 10.1039/D0EE00092B

  18. [18]

      C. Li, X. Han, F. Cheng, et al., Nat. Commun. 6 (2015) 7345. doi: 10.1038/ncomms8345

  19. [19]

      P. Zhang, L. Wang, S. Yang, et al., Nat. Commun. 8 (2017) 15020. doi: 10.1038/ncomms15020

  20. [20]

      S.W.K. Andreas Stein, T.E. Mallouk, Science 259 (1993) 1558–1564. doi: 10.1126/science.259.5101.1558

  21. [21]

      M. Bianchini, J. Wang, R.J. Clement, et al., Nat. Mater. 19 (2020) 1088–1095. doi: 10.1038/s41563-020-0688-6

  22. [22]

      J. Diao, Y. Qiu, S. Liu, et al., Adv. Mater. 32 (2020) e1905679. doi: 10.1002/adma.201905679

  23. [23]

      R. Li, D. Speed, D. Siriwardena, et al., Chem. Eng. J. 425 (2021) 131785. doi: 10.1016/j.cej.2021.131785

  24. [24]

      K. Paździor, L. Bilińska, S. Ledakowicz, Chem. Engin. J. 376 (2019) 120597. doi: 10.1016/j.cej.2018.12.057

  25. [25]

      J.J. Ye, P.H. Li, H.R. Zhang, et al., Adv. Funct. Mater. 33 (2023) 2305659. doi: 10.1002/adfm.202305659

  26. [26]

      J. Chen, X.Y. Chen, Y. Liu, et al., Energ. Environ. Sci. 16 (2023) 792–829. doi: 10.1039/D2EE03015B

  27. [27]

      Y. Wen, J. Yan, B. Yang, Z. Zhuang, Y. Yu, J. Mater. Chem. A 10 (2022) 19184–19210. doi: 10.1039/D2TA02188A

  28. [28]

      W. Shao, M. Xiao, C. Yang, et al., Small 18 (2022) e2105763. doi: 10.1002/smll.202105763

  29. [29]

      J.R. Chamorro, T.M. McQueen, Acc. Chem. Res. 51 (2018) 2918–2925. doi: 10.1021/acs.accounts.8b00382

  30. [30]

      S.R. Bauers, S.R. Wood, K.M. Jensen, et al., J. Am. Chem. Soc. 137 (2015) 9652–9658. doi: 10.1021/jacs.5b04838

  31. [31]

      S. Ahlawat, K.R. Mote, N.A. Lakomek, V. Agarwal, Chem. Rev. 122 (2022) 9643–9737. doi: 10.1021/acs.chemrev.1c00852

  32. [32]

      O. Bubnova, C. Pastore, W. Sun, A. Weingarten, ACS Nano 13 (2017) 12772–12779.

  33. [33]

      T. Chirayil, P.Y. Zavalij, M.S. Whittingham, Chem. Mater. 10 (1998) 2629–2640. doi: 10.1021/cm980242m

  34. [34]

      N. Bahlawane, D. Lenoble, Chem. Vap. Deposition 20 (2014) 299–311. doi: 10.1002/cvde.201400057

  35. [35]

      Y. He, C. Chen, Y. Liu, et al., Nano Lett. 22 (2022) 4970–4978. doi: 10.1021/acs.nanolett.2c01666

  36. [36]

      G. Fang, Y. Deng, M. Huang, et al., Environ. Sci. Technol. 52 (2018) 2178–2185. doi: 10.1021/acs.est.7b05303

  37. [37]

      X. Liu, J. Wu, S. Zhang, et al., Appl. Catal. B: Environ. 320 (2023) 121994. doi: 10.1016/j.apcatb.2022.121994

  38. [38]

      H. Li, J. Shang, Z. Yang, et al., Environ. Sci. Technol. 51 (2017) 5685–5694. doi: 10.1021/acs.est.7b00040

  39. [39]

      L. Zhang, S. Wang, C. Lu, Anal. Chem. 87 (2015) 7313–7320. doi: 10.1021/acs.analchem.5b02267

  40. [40]

      Y. Yang, G. Banerjee, G.W. Brudvig, J.H. Kim, J.J. Pignatello, Environ. Sci. Technol. 52 (2018) 5911–5919. doi: 10.1021/acs.est.8b00735

  41. [41]

      X. Li, X. Liu, C. Lin, et al., Chem. Eng. J. 382 (2020) 123013. doi: 10.1016/j.cej.2019.123013

• 

  Figure 1  (a) Schematic illustration of the sample synthesis process. (b) XRD pattern of annealed VCl₃-graphene at different mass proportions. (c) SEM and magnified SEM image of defective V₂O₅@graphene. (d, e) TEM and HRTEM image of defective V₂O₅@graphene. (f) The associated FFT analysis taken from the regions outlined in (e). (g) Elemental mapping images of defective V₂O₅@graphene.

  下载: 全尺寸图片 幻灯片
  

  Figure 2  (a) The degradation of RhB in pure graphene/H₂O₂, V₂O₅@graphene/H₂O_2, V₂O₅@graphene, graphene+V₂O₅/H₂O₂ and pure V₂O₅/H₂O₂ reaction systems. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [RhB] = 10 mg/L and pH 7.0. (b) Corresponding kinetic curves of the different catalytic systems. (c) Comparison of k_obs of different pollutant degradation via Fenton-like oxidation in this work and the previous reports (details in Table S2 in Supporting information). (d) Mineralization efficiency of different pollutants including RhB (10 mg/L), MB (20 mg/L), MR (20 mg/L), BPA (20 mg/L) and TCP (10 mg/L) within 4 h. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt% and pH 7.0.

  下载: 全尺寸图片 幻灯片
  

  Figure 3  (a) Schematic illustration of the Fenton-like catalysis mechanism via defective V₂O₅@graphene/H₂O₂ system. (b) EPR spectra of DMPO adducts in V₂O₅@graphene/H₂O₂, pure H₂O₂, pure graphene/H₂O₂, pure V₂O₅/H₂O₂ and V₂O₅@graphene reaction systems. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [DMPO] = 100 mmol/L, and pH 7.0. (c) High-resolution XPS spectrum of V 2p and O 1s of defective V₂O₅@graphene and pure V₂O₅ fresh and used. (d) The quenching experiments with existence of 1 mmol/L CH₃OH, 10 mmol/L CH₃OH in the defective V₂O₅@graphene/H₂O₂ catalytic system. Reaction conditions: [catalyst] = 0.25 g/L, [H₂O₂] = 200 µL 30 wt%, [RhB] = 10 mg/L and pH 7.0.

  下载: 全尺寸图片 幻灯片
•