Iron single-atom catalysts created in constrained space with in-situ-formed carbon layers for efficient Fenton reaction

doi:10.1016/S1872-2067(26)65114-5

Abstract

Abstract:

Phenol is a common organic pollutant in industrial wastewater and must be strictly controlled and discharged to meet standards to prevent ecological health risks. Traditional Fenton method faces challenges such as low utilization of active sites in iron-based catalysts, leaching of metallic iron, and limited pH adaptability. In this work, we introduce a solid-grinding followed by heat-treatment (SH) method for the synthesis of iron single-atom catalysts (SACs). This approach leverages the unique constrained space which is between the silica walls and the template within template-loaded SBA-15 (TLS). The precursor Fe(NO₃)₃ is able to penetrate the constrained space through solid-grinding. During the following heat treatment process, iron single atoms are formed and stabilized in the in-situ carbon layers formed by the template, resulting in the formation of a novel SAC, named as Fe₁@C-TLS. Experiments and theoretical calculations reveal that the constrained space effectively inhibits the migration and agglomeration of iron atoms to form a unique Fe-C₃ coordination structure. The Fe₁@C-TLS catalyst exhibits excellent activity (k = 0.102 min⁻¹) in the Fenton reaction for the degradation of phenol, significantly outperforming the Fe@TRS nanoparticle catalyst prepared without constrained space (k = 0.0115 min⁻¹), as well as reported iron and other transition metals-based catalysts.

Key words: Single-atom catalysts, Iron, Constrained space, Carbon layers, Phenol degradation

Yang Wang, Cun-Feng Fan, Yang Liu, Xiao-Qin Zheng, Xuan-Yi Liu, Kai Zhang, Jiahui Kou, Hengming Huang, Lin-Bing Sun. Iron single-atom catalysts created in constrained space with in-situ-formed carbon layers for efficient Fenton reaction[J]. Chinese Journal of Catalysis, 2026, 88: 432-441.

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URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(26)65114-5

https://www.cjcatal.com/EN/Y2026/V88/I9/432

Figures/Tables 6

Fig. 1. A schematic representation illustrating the synthesis process of catalysts comprising individual iron atoms and iron nanoparticles. (a) Synthesis of single iron atoms anchored on in-situ-generated carbon layers within constrained space in TLS by the SH method. (b) Synthesis of aggregated Fe2O3 in a traditional carrier TRS with no constrained space.

Fig. 2. Materials characterization. (a) Low-angle XRD patterns for the samples TLS, Fe1@C-TLS, C-TLS, Fe@TRS, and TRS. (b) Nitrogen adsorption-desorption isotherms for TLS, before and after the incorporation of Fe(NO3)3, with the corresponding pore size distribution shown in the inset. (c) DTG curves for Fe(NO3)3@TLS, Fe(NO3)3@TRS, C-TLS, and TLS. (d) TG-MS analysis for Fe(NO3)3@TLS. (e) HAAFD-STEM image for Fe1@C-TLS. Red circles indicate the locations of single-atom bright spots. (f) HAAFD-STEM image for Fe@TRS. The nanoparticles are indicated by yellow circles.

Fig. 3. Investigation of local chemical environment and valence. (a) XPS spectra of Fe 2p for Fe1@C-TLS and Fe@TRS. (b) XPS spectra of C 1s for Fe1@C-TLS and C-TLS. (c) Normalized Fe K-edge XANES spectra of Fe1@C-TLS, Fe@TRS, Fe2O3, and Fe foil. (d) Fourier transform k3-weighted EXAFS spectra for Fe1@C-TLS, Fe@TRS, Fe2O3, and Fe foil. (e) Fitted EXAFS curve in R-space for Fe1@C-TLS. (f) Fitted EXAFS curve in k-space for Fe1@C-TLS. (g) WT image of Fe2O3. (h) WT image of Fe@TRS. (i) WT image of Fe1@C-TLS.

Fig. 4. Catalytic performance on Fenton phenol degradation. (a) The degradation of phenol by different catalysts (reaction conditions: pH = 3.0 ± 0.2, [catalyst] = 0.1 g·L?1, [phenol] = 20 mg·L?1, [H2O2] = 1000 ppm, T = 40 °C). (b) The corresponding kinetic curves for phenol degradation by Fe@TRS and Fe1@C-TLS at 40 °C. (c) A comparative study of the performance of typical catalysts on the degradation kinetics of organic pollutants. (d) The degradation of phenol by Fe1@C-TLS at different H2O2 concentrations (reaction conditions: pH = 3.0 ± 0.2, [Catalyst] = 0.1 g·L?1, [phenol] = 20 mg·L?1, T = 40 °C). (e) The degradation of phenol by Fe1@C-TLS at different pH values. (Reaction conditions: [Catalyst] = 0.1 g·L?1, [phenol] = 20 mg·L?1, [H2O2] = 1000 ppm, T = 40 °C). (f) The degradation of phenol by Fe1@C-TLS at different temperatures (reaction conditions: pH = 3.0 ± 0.2, [Catalyst] = 0.1 g·L?1, [phenol] = 20 mg·L?1, [H2O2] = 1000 ppm).

Fig. 5. Examination of phenol degradation mechanism. (a) Degradation performance of the catalyst Fe1@C-TLS and the leaching situation of Fe1@C-TLS at 20 min. (b) CV curves of Fe1@C-TLS and Fe@TRS. (c) EIS spectra of Fe1@C-TLS and Fe@TRS. (d) EPR spectra of the Fenton reaction catalyzed by Fe1@C-TLS at different pH values. (e) Schematic diagram of the Fe1@C-TLS catalytic mechanism for phenol degradation. (f) The effect of TBA on the degradation of phenol in Fe1@C-TLS.

Fig. 6. Theoretical calculations. (a) Relative energy change for the conversion of H2O2 to •OH by Fe-C3 (A), Fe-C3 (B), Fe-C4 and Fe2O3. Charge transfer between metal atoms and carriers of (b) Fe-C3 (A), (c) Fe-C3 (B) and (d) Fe-C4.

References

[1]	F. Deng, H. Olvera-Vargas, M. Zhou, S. Qiu, I. Sirés, E. Brillas, Chem. Rev., 2023, 123, 4635-4662.
[2]	H. Sheng, A. N. Janes, R. D. Ross, D. Kaiman, J. Huang, B. Song, J. R. Schmidt, S. Jin, Energy Environ. Sci., 2020, 13, 4189-4203.
[3]	M. He, Z. Xu, D. Hou, B. Gao, X. Cao, Y. S. Ok, J. Rinklebe, N. S. Bolan, D. C. W. Tsang, Nat. Rev. Earth Environ., 2022, 3, 444-460.
[4]	D. Meyerstein, Nat. Rev. Chem., 2021, 5, 595-597.
[5]	R. Zhu, Y. Zhu, H. Xian, L. Yan, H. Fu, G. Zhu, Y. Xi, J. Zhu, H. He, Appl. Catal. B, 2020, 270, 118891.
[6]	Y. Ahmed, J. Zhong, Z. Yuan, J. Guo, J. Hazard. Mater., 2022, 430, 128408.
[7]	J. Xu, Q. Zhang, X. Gao, P. Wang, H. Che, C. Tang, Y. Ao, Angew. Chem. Int. Ed., 2023, 62, e202307018.
[8]	L. Su, P. Wang, X. Ma, J. Wang, S. Zhan, Angew. Chem. Int. Ed., 2021, 60, 21261-21266.
[9]	J. Tang, J. Wang, Environ. Sci. Technol., 2018, 52, 5367-5377.
[10]	D. He, H. Niu, S. He, L. Mao, Y. Cai, Y. Liang, Water Res., 2019, 162, 151-160.
[11]	Z. Tan, P. Cao, S. Chen, H. Yu, Y. Su, X. Quan, Appl. Catal. B, 2024, 355, 124170.
[12]	M. Wu, X. Guo, Y. Cao, H. Yu, Z. Hu, Y. Yang, T. Yao, J. Wu, Chem. Eng. J., 2024, 489, 151091.
[13]	C. Gao, S. Chen, X. Quan, H. Yu, Y. Zhang, J. Catal., 2017, 356, 125-132.
[14]	J. Liang, Q. Xiang, W. Lei, Y. Zhang, J. Sun, H. Zhu, S. Wang, J. Hazard. Mater., 2021, 412, 125195.
[15]	T. W. Leal, L. A. Lourenço, H. de, L. Brandão, A. da Silva, S,. M. A. G. U. de Souza, A. A. U. de Souza, J. Hazard. Mater., 2018, 359, 96-103.
[16]	J. Liu, Z. Yang, S. Li, Y. Du, Z. Zhang, J. Shao, M. Willatzen, Z.-L. Wang, D. Wei, J. Am. Chem. Soc., 2024, 146, 31574-31584.
[17]	X. Zhang, B. Xu, S. Wang, X. Li, B. Liu, Y. Xu, P. Yu, Y. Sun, J. Hazard. Mater., 2022, 423, 127039.
[18]	I. Amildon Ricardo, C. E. S. Paniagua, V. A. B. Paiva, B. R. Gonçalves, R. M. F. Sousa, A. E. H. Machado, A. G. Trovó Chem. Eng. J., 2018, 339, 531-538.
[19]	Y. Wang, Y. Zhou, X.-Q. Zheng, K. Zhang, Y. Liu, X.-Y. Liu, X. Yang, Z. Xu, J. Kou, L.-B. Sun, Appl. Surf. Sci., 2025, 702, 163333.
[20]	X. Qin, P. Cao, X. Quan, K. Zhao, S. Chen, H. Yu, Y. Su, Environ. Sci. Technol., 2023, 57, 2907-2917.
[21]	M. J. Kim, M. W. Lee, K.-Y. Lee, Appl. Surf. Sci., 2021, 541, 148409.
[22]	L. Wang, C. Hou, L. Luo, B. Xiang, Z. Zhu, C. Wang, Appl. Catal. B, 2025, 371, 125281.
[23]	C. Yuan, G. Li, M. Ran, W. Yang, P. Shu, X. Long, W. Li, Appl. Catal. B, 2025, 366, 125002.
[24]	Q. Xia, D. Zhang, Z. Yao, Z. Jiang, Chemosphere, 2022, 289, 133195.
[25]	J. Liu, X. Li, B. Liu, C. Zhao, Z. Kuang, R. Hu, B. Liu, Z. Ao, J. Wang, ACS Appl. Mater. Interfaces, 2018, 10, 38051-38056.
[26]	M.-X. Gu, X.-Q. Zheng, S.-S. Peng, S.-C. Qi, X.-Q. Liu, L.-B. Sun, ACS Sustainable Chem. Eng., 2023, 11, 7844-7850.
[27]	L. Yang, Z. Wu, T. Tian, B. Huang, X. Wang, Y. Zhang, H. Zhang, C.-S. He, Z. Xiong, B. Lai, ACS Nano, 2025, 19, 26701-26714.
[28]	X. Wei, H. Wu, F. Sun, J. Colloid Interface Sci., 2017, 504, 611-619.
[29]	G. M. S. ElShafei, A. M. Al-Sabagh, F. Z. Yehia, C. A. Philip, N. A. Moussa, G. Eshaq, A. E. ElMetwally, Appl. Catal. B, 2018, 224, 681-691.
[30]	M. Wang, G. Fang, P. Liu, D. Zhou, C. Ma, D. Zhang, J. Zhan, Appl. Catal. B, 2016, 188, 113-122.
[31]	S. Zhang, Z. Lu, C. Hu, F. Li, Adv. Sci., 2024, 11, 2307151.
[32]	F. Chen, X.-L. Wu, C. Shi, H. Lin, J. Chen, Y. Shi, S. Wang, X. Duan, Adv. Funct. Mater., 2021, 31, 2007877.
[33]	Y. Wang, Y. Zhou, X.-Y. Liu, X.-Q. Zheng, S.-J. Wang, K. Zhang, X.-B. Shao, J. Kou, L.-B. Sun, Chem. Eng. J., 2025, 519, 164766.
[34]	X.-B. Shao, X.-R. Song, S.-S. Peng, X.-Q. Zheng, S.-C. Qi, P. Tan, X.-Q. Liu, L.-B. Sun, Chem. Eng. J., 2024, 481, 148398.
[35]	L. Duan, H. Jiang, B. Cai, J. Wang, W. Wu, D. Lin, K. Yang, Adv. Funct. Mater., 2025, 35, e09337.
[36]	Y. Yin, R. Fang, B. Hu, Q. Wang, A. H. Asif, C. Zhu, W. Li, L. He, S. Cui, S. Wang, H. Sun, Ind. Eng. Chem. Res., 2024, 63, 15165-15175.
[37]	M. Yang, H. Li, F. Liu, S. Sun, J. Mei, Y. Jiao, J. Cui, Y. Xu, H. Song, Z. Duan, W. Liu, Y. Ren, Appl. Catal. B, 2024, 354, 124071.
[38]	C.-H. Gu, Y. Pan, T.-T. Wei, A.-Y. Zhang, Y. Si, C. Liu, Z.-H. Sun, J.-J. Chen, H.-Q. Yu, Nat. Water, 2024, 2, 649-662.
[39]	K. Zhu, W. Qin, Y. Chen, X. Liang, H. Xin, Z. Huang, H. F. Garces, Y. Gan, M. Sillanpää, R. Qiu, G. Guan, K. Yan, Nano Today, 2024, 58, 102462.
[40]	B. Wang, C. Cheng, M. Jin, J. He, H. Zhang, W. Ren, J. Li, D. Wang, Y. Li, Angew. Chem. Int. Ed., 2022, 61, e202207268.
[41]	S. Ncube, Z. Tian, J. Lin, H. Zhang, S. Wang, W. Tian, Small, 2025, 21, 2504746.
[42]	H. Fu, J. Wei, G. Chen, M. Xu, J. Liu, J. Zhang, K. Li, Q. Xu, Y. Zou, W.-X. Zhang, S. Xi, X. Chen, S. Li, L. Ling, Appl. Catal. B, 2023, 321, 122012.
[43]	J. Qu, Y. Xu, X. Zhang, M. Sun, Y. Tao, X. Zhang, G. Zhang, C. Ge, Y. Zhang, Appl. Catal. B, 2022, 316, 121639.