Microstructure modulation of α-MnO2 via mild urea-induced phase transition for enhanced catalytic ozonation of emerging contaminants

doi:10.1016/S1872-2067(25)64889-3

Chinese Journal of Catalysis ›› 2026, Vol. 84: 175-188.DOI: 10.1016/S1872-2067(25)64889-3

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Microstructure modulation of α-MnO₂ via mild urea-induced phase transition for enhanced catalytic ozonation of emerging contaminants

Peixin Zhu^a, Mengyao Xiao^a, Xixi Chen^c(), Jingsong Luo^d, Zhong Fang^d, Long Chen^d, Huinan Zhao^a, Chun He^a^,^b, Shuanghong Tian^a^,^b()

^a School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
^b Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation, Guangzhou 510275, Guangdong, China
^c Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong 610200, China
^d China National Chemical Southern Construction Investment Co., Ltd., Guangzhou 516000, Guangdong, China

Received:2025-09-01 Accepted:2025-09-15 Online:2026-05-18 Published:2026-04-16
Contact: *E-mail: xixichen@cityu.edu.hk, chenxixi8117@163.com (X. Chen),
tshuangh@mail.sysu.edu.cn (S. Tian).
About author:First author contact:CRediT authorship contribution statement
Peixin Zhu: Methodology, Software, Writing - original draft. Mengyao Xiao: Investigation, Data curation. Xixi Chen: Supervision, Conceptualization, Data curation, Writing - review & editing. Jingsong Luo: Resources, Funding acquisition. Zhong Fang: Resources, Funding acquisition. Long Chen: Resources, Funding acquisition. Huinan Zhao: Supervision, Conceptualization, Writing - review & editing. Chun He: Supervision, Conceptualization, Writing - review & editing. Shuanghong Tian: Supervision, Conceptualization, Writing - review & editing, Funding acquisition.
Supported by:
National Key Research and Development Program of China(2024YFC3712500);National Natural Science Foundation of China(22376229);Guangdong Basic and Applied Basic Research Foundation(2023A1515010037)

Abstract

Abstract:

While facet engineering and heterostructure construction are recognized as effective strategies for enhancing catalytic performance through defect creation, their integration remains scarce and challenging. This study develops a mild urea-assisted thermal strategy to construct an oxygen vacancy (OV)-rich α-MnO₂(310)/Mn₃O₄ heterojunction (Mn400-0.125U), comprising 48.6% α-MnO₂ with preferentially exposed (310) facets and 51.4% Mn₃O₄. The low OV formation energy on (310) facets coupled with heterojunction interfaces effects leads to a high OV concentration. Mn400-0.125U demonstrated exceptional catalytic ozonation performance, achieving a sulfamethoxazole degradation rate constant (7.7×10^-2 min^-1), which is 1.8-, 1.6-, and 3.3-fold higher than those of α-MnO₂, Mn₃O₄, and single ozonation, respectively. Operational advantages include ultralow catalyst dosage (0.1 g/L), broad pH adaptability (3.5-10.5), and remarkable resilience against aqueous matrix interference (≤ 12.4% efficiency loss). Both experimental and theoretical calculations demonstrate that the abundant OVs, combined with the proper hydrophilicity of Mn400-0.125U, synergistically trigger barrier-free activation and decomposition of ozone, subsequently generating a series of reactive species via chain reactions. A hybrid oxidation regime was identified where the non-radical pathway mediated by electron-transfer, O* (surface oxygen atoms), and ¹O₂predominates over radical pathways (•O₂^-/•OH). This work establishes a facile coupled modulation protocol for creating defect-rich manganese oxides applied in catalytic ozonation of emerging contaminants.

Key words: Facet engineering, Heterojunction, Manganese-based catalysts, Oxygen vacancy, Catalytic ozonation

Peixin Zhu, Mengyao Xiao, Xixi Chen, Jingsong Luo, Zhong Fang, Long Chen, Huinan Zhao, Chun He, Shuanghong Tian. Microstructure modulation of α-MnO₂ via mild urea-induced phase transition for enhanced catalytic ozonation of emerging contaminants[J]. Chinese Journal of Catalysis, 2026, 84: 175-188.

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URL: https://www.cjcatal.com/EN/10.1016/S1872-2067(25)64889-3

https://www.cjcatal.com/EN/Y2026/V84/I5/175

Figures/Tables 8

Fig. 1. (a) Schematic diagram of modulating the microstructure of α-MnO2. (b) Photograph of the modulated catalysts. XRD patterns of the catalysts modulated by urea-assisted thermal treatment at 400 °C (c) and 200 °C (d) with different urea dosage. Characteristic diffraction peaks at 18.1°, 28.9°, 37.6°, 42.0°, 49.9°, 60.2°, and 65.1° are corresponded to the (200), (310), (211), (301), (411), (521), and (022) planes of tetragonal α-MnO2 (JCPDS 44-0141). Characteristic diffraction peaks emerged at 18.0°, 31.0°, 32.3°, 36.1°, 44.4°, 59.8°, and 65.4° are indexed to the (101), (200), (103), (211), (220), (224), and (323) planes of tetragonal Mn3O4 (JCPDS 24-0734).

Fig. 2. SEM images of the pristine MnO2 (a), the modulated Mn400-0U (b), Mn400-0.125U (c), and Mn400-0.250U (d). TEM (e1-e2) and HRTEM (e3-e4) images of Mn400-0.125U (α-MnO2/Mn3O4). (e5) HRTEM images of Mn400-0.125U (α-MnO2/Mn3O4) after cycled reaction. (f1-f4) EDS elemental mapping images of Mn400-0.125U (α-MnO2/Mn3O4). Water contact angle measurements on Mn400-0U (α-MnO2) (g1), Mn400-0.125U(g2), and Mn400-0.250U (Mn3O4) (g3).

Fig. 3. XPS spectra of Mn 2p (a), O 1s (b), and N 1s (c) of Mn400-0U, Mn400-0.125U and Mn400-0.250U. ESR profiles (d) and Raman spectra (e) of Mn400-0U, Mn400-0.125U and Mn400-0.250U.

Table 1 Oxygen vacancies analysis of the catalysts indicated by XPS, ESR, and Raman.

Sample	[O_ads]/ [O_total]	[Mn²⁺+Mn³⁺] /[Mn_total]	ESR Intensity(a.u.) g = 2.003	Raman v₂/v₃(Mn-O)
Mn400-0U	21.9%	53.1%	0.24	1.254
Mn400-0.125U	34.3%	68.2%	0.72	1.087
Mn400-0.250U	30.0%	57.3%	0.33	1.202

Fig. 4. H2-TPR (a), EIS (b) and CV (c) curves of Mn400-0U, Mn400-0.125U and Mn400-0.250U.

Fig. 5. Removal of SMZ (a,b) and pseudo first-order kinetics fitting (c) for SMZ removal in ozonation and catalytic ozonation. Effects of catalyst dosage of Mn400-0.125U (d), initial solution pH (e,f), and water matrices (g) on the removal of SMZ or the pseudo first-order reaction constant of SMZ removal by catalytic ozonation. (h) Stability assessments by recyclability of Mn400-0.125U.

Fig. 6. (a) Evolution of ozone concentration along with the time in ozonation and catalytic ozonation. Effect of scavengers (b) and pseudo first-order kinetics fitting (c) for SMZ removal in Mn400-0.125U/O3 system. ESR spectra of DMPO-?OH (d), DMPO/DMSO-?O2? (e) and TEMP-1O2 adducts (f) in ozonation and catalytic ozonation.

Fig. 7. Optimized geometry structures and the calculated energy of M310-O3 (a), M310-OV-O3 (b), M310-OV-H2O-O3 (c), M101-O3 (d), and M101-H2O-O3 (e).

References

[1]	A. Aziz, N. Ali, A. Khan, M. Bilal, S. Malik, N. Ali, H. Khan, Int. J. Biol. Macromol., 2020, 153, 502-512.
[2]	N. Ali, A. Khan, M. Bilal, S. Malik, S. Badshah, H. M. N. Iqbal, Molecules, 2020, 25, 226.
[3]	N. Ali, A. Khan, S. Malik, S. Badshah, M. Bilal, H. M. N. Iqbal, J. Environ. Chem. Eng., 2020, 8, 104064.
[4]	W. Yang, T. Wu, Ind. Eng. Chem. Res., 2019, 58, 3468-3477.
[5]	A. M. Gorito, J. F. J. R. Pesqueira, N. F. F. Moreira, A. R. Ribeiro, M. F. R. Pereira, O. C. Nunes, C. M. R. Almeida, A. M. T. Silva, J. Environ. Chem. Eng., 2021, 9, 105315.
[6]	P. C. C. Faria, D. C. M. Monteiro, J. J. M. Órfão, M. F. R. Pereira, Chemosphere, 2009, 74, 818-824.
[7]	J. Wang, Y. Lou, C. Xu, S. Song, W. Liu, Sep. Purif. Technol., 2016, 159, 57-67.
[8]	M. Alameddine, Z. T. How, M. Gamal El-Din, Sci. Total Environ., 2021, 770, 144679.
[9]	M. A. Prada-Vásquez, S. E. Estrada-Flórez, E. A. Serna-Galvis, R. A. Torres-Palma, Sci. Total Environ., 2021, 765, 142699.
[10]	J. Wang, H. Chen, Sci. Total Environ., 2020, 704, 135249.
[11]	B. Zhu, X.-S. Li, P. Sun, J.-L. Liu, X.-Y. Ma, X. Zhu, A.-M. Zhu, Chin. J. Catal., 2017, 38, 1759-1769.
[12]	M. Sui, B. Duan, L. Sheng, S. Huang, L. She, Chin. J. Catal., 2012, 33, 1284-1289.
[13]	G. Yu, Y. Wang, H. Cao, H. Zhao, Y. Xie, Environ. Sci. Technol., 2020, 54, 5931-5946.
[14]	H. Huang, W. Li, X. Chen, Z. Yang, M. Chen, A. Zhang, C. He, S. Tian, ACS Appl. Mater. Interfaces, 2025, 17, 12177-12188.
[15]	Y. Yang, Z. Yang, Z. Lai, C. Yang, Y. Hou, H. Tao, J. Zhang, M. Anpo, X. Fu, Chin. J. Catal., 2025, 72, 143-153.
[16]	G. Zhu, J. Zhu, W. Jiang, Z. Zhang, J. Wang, Y. Zhu, Q. Zhang, Appl. Catal. B, 2017, 209, 729-737.
[17]	G. Li, Y. Lu, C. Lu, M. Zhu, C. Zhai, Y. Du, P. Yang, J. Hazard. Mater., 2015, 294, 201-208.
[18]	J. Ma, C. Wang, H. He, Appl. Catal. B, 2017, 201, 503-510.
[19]	H. Xu, N. Yan, Z. Qu, W. Liu, J. Mei, W. Huang, S. Zhao, Environ. Sci. Technol., 2017, 51, 8879-8892.
[20]	H. Wang, L. Peng, G. Li, H. Liu, Z. Liang, H. Zhao, T. An, Appl. Catal. B, 2024, 344, 123675.
[21]	T. Ba, C. Wang, Q. Feng, J. Sun, X. Shi, J. Water Process. Eng., 2023, 53, 103716.
[22]	Y. Wang, T. Zhou, D. Chen, Z.-X. Zhang, Q. Zhang, X. Ye, J. Wan, J.-P. Zou, Appl. Catal. B, 2024, 353, 124106.
[23]	C. He, Y. Wang, Z. Li, Y. Huang, Y. Liao, D. Xia, S. Lee, Environ. Sci. Technol., 2020, 54, 12771-12783.
[24]	Y. Wang, X. Hu, H. Song, Y. Cai, Z. Li, D. Zu, P. Zhang, D. Chong, N. Gao, Y. Shen, C. Li, Appl. Catal. B, 2021, 299, 120677.
[25]	J. Liu, C. Meng, X. Zhang, S. Wang, K. Duan, X. Li, Y. Hu, H. Cheng, Chem. Eng. J., 2023, 466, 143319.
[26]	P. Wu, S. Dai, G. Chen, S. Zhao, Z. Xu, M. Fu, P. Chen, Q. Chen, X. Jin, Y. Qiu, S. Yang, D. Ye, Appl. Catal. B, 2020, 268, 118418.
[27]	Y. Jing, A. Fan, J. Guo, T. Shen, S. Yuan, Y. Chu, Chem. Eng. J., 2022, 429, 132193.
[28]	C. Akshhayya, M. K. Okla, A. A. AL-ghamdi, M. A. Abdel-Maksoud, H. AbdElgawad, A. Das, S. S. Khan, Surf. Interfaces, 2021, 27, 101523.
[29]	K. Natarajan, M. Saraf, A. K. Gupta, S. M. Mobin, Ind. Eng. Chem. Res., 2020, 59, 7584-7593.
[30]	P. Zheng, J. Su, Y. Wang, W. Zhou, J. Song, Q. Su, N. Reeves-McLaren, S. Guo, ChemSusChem, 2020, 13, 1793-1799.
[31]	J. Gao, H. Wang, Y. Zhou, Z. Liu, Y. He, J. Alloys Compd., 2022, 892, 162151.
[32]	V. Meena, D. Swami, A. Chandel, N. Joshi, S. O. Prasher, J. Hazard. Mater., 2025, 483, 136541.
[33]	G. Zhao, J. Wang, W. Chen, W. Zhang, L. Jin, X. Huang, J. Hazard. Mater., 2025, 492, 138089.
[34]	G. Kresse, J. Furthmüller, Comput. Mater. Sci., 1996, 6, 15-50.
[35]	J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865-3868.
[36]	S. Rong, P. Zhang, F. Liu, Y. Yang, ACS Catal., 2018, 8, 3435-3446.
[37]	S. Zhan, H. Huang, C. He, Y. Xiong, P. Li, S. Tian, Appl. Catal. B, 2023, 321, 122040.
[38]	W. Q. Li, Z. H. Wen, S. H. Tian, L. J. Shan, Y. Xiong, Catal. Sci. Technol., 2018, 8, 1051-1061.
[39]	J. Zhou, B. Feng, X. Kong, L. Li, Z. Li, X. Tian, M. Feng, S. Qu, J. Wang, Dalton Trans., 2022, 51, 18622-18632.
[40]	X. Li, X. Yan, S. Zuo, X. Lu, S. Luo, Z. Li, C. Yao, C. Ni, Chem. Eng. J., 2017, 320, 211-221.
[41]	S. He, K. Xiao, X.-Z. Chen, T. Li, T. Ouyang, Z. Wang, M.-L. Guo, Z.-Q. Liu, J. Colloid Interface Sci., 2019, 557, 644-654.
[42]	C. Pei, Y. Wang, Y. Ding, R. Li, W. Shu, Y. Zeng, X. Yin, J. Wan, Adv. Mater., 2023, 35, 2209083.
[43]	K. Wang, M. Pei, Y. Shuai, Y. Liu, S. Deng, Z. Zhuang, K. Sun, W. Yan, J. Zhang, ACS Energy Lett., 2024, 9, 4682-4690.
[44]	S. Dang, Y. Wen, T. Qin, J. Hao, H. Li, J. Huang, D. Yan, G. Cao, S. Peng, Chem. Eng. J., 2020, 396, 125342.
[45]	T. Mathew, K. Suzuki, Y. Ikuta, N. Takahashi, H. Shinjoh, Chem. Commun., 2012, 48, 10987-10989.
[46]	J. Wang, D. Li, P. Li, P. Zhang, Q. Xu, J. Yu, RSC Adv., 2015, 5, 100434-100442.
[47]	Y. He, L. Wang, Z. Chen, B. Shen, J. Wei, P. Zeng, X. Wen, Sci. Total Environ., 2021, 785, 147328.
[48]	W. Lu, J. Chen, L. Kong, F. Zhu, Z. Feng, J. Zhan, Sens. Actuat. B, 2021, 333, 129560.
[49]	J. Wu, H. Xie, G. Zhang, H. Lin, J. Xing, L. Wang, J. Xu, Chem. Eng. J., 2024, 499, 156402.
[50]	C. M. Julien, M. Massot, Mater. Sci. Eng. B, 2003, 97, 217-230.
[51]	M. Polverejan, J. C. Villegas, S. L. Suib, J. Am. Chem. Soc., 2004, 126, 7774-7775.
[52]	Y. J. Wei, L. Y. Yan, C. Z. Wang, X. G. Xu, F. Wu, G. Chen, J. Phys. Chem. B, 2004, 108, 18547-18551.
[53]	F. Shi, B. Yang, Z. Xiong, Y. Cheng, C. Ma, T. Huang, G. Wen, Water Res., 2025, 273, 123027.
[54]	Y. Dai, G. Liu, X. Sun, J. Ma, T. Xian, H. Yang, Appl. Surf. Sci., 2025, 681, 161611.
[55]	H. Liu, J. Wang, H. Yu, H. Xiong, Y. Chen, C. Wang, J. Xiao, ACS Sens., 2022, 7, 2978-2986.
[56]	O. Bochkova, A. Stepanov, A. Khazieva, B. Akhmadeev, I. Ismaev, K. Kholin, I. Nizameev, A. Sapunova, A. Voloshina, A. Laskin, D. Smekalov, M. Tarasov, Y. Budnikova, A. Mustafina, Mater. Today Chem., 2023, 33, 101706.
[57]	D. Xia, W. Xu, Y. Wang, J. Yang, Y. Huang, L. Hu, C. He, D. Shu, D. Y. C. Leung, Z. Pang, Environ. Sci. Technol., 2018, 52, 13399-13409.
[58]	S. Tian, S. Zhan, Z. Lou, J. Zhu, J. Feng, Y. Xiong, J. Catal., 2021, 398, 1-13.
[59]	Z. Xie, L. Ji, H. Bian, Q. Zhang, Chem. Eng. J., 2025, 509, 161202.
[60]	A. C. Mecha, M. N. Chollom, Environ. Chem. Lett., 2020, 18, 1491-1507.
[61]	D. Wang, Y. He, Y. Chen, F. Yang, Z. He, T. Zeng, X. Lu, L. Wang, S. Song, J. Ma, Water Res., 2023, 230, 119574.
[62]	M. Sui, S. Xing, L. Sheng, S. Huang, H. Guo, J. Hazard. Mater., 2012, 227-228, 227-236.
[63]	T. Tian, P. Zhu, C. He, Y. Xiong, J. Fang, S. Tian, Appl. Catal. B, 2024, 359, 124463.
[64]	L. Zhu, H. Wang, J. Sun, L. Lu, S. Li, Environ. Sci. Technol., 2024, 58, 6753-6762.

Microstructure modulation of α-MnO₂ via mild urea-induced phase transition for enhanced catalytic ozonation of emerging contaminants

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