Interface Reconstruction of nZVI with a Mesoporous Mg(OH)2 Shell: Coupled Mass Transport and Interfacial Electron Transfer During Perchlorate Transformation
- 1Nanjing Institute of Environmental Science, Ministry of Ecology and Environment of the People’s Republic of China, Nanjing 210042, China
- 2College of Environment, Hohai University, Nanjing 210098, China
- 3Xuyi Ecological Environment Comprehensive Administrative Law Enforcement Bureau, Huai’an 211700, China
Abstract
Perchlorate (ClO4−) is kinetically persistent in aqueous environments because of its highly symmetric tetrahedral structure and the high activation barrier for Cl−O bond cleavage. Although nanoscale zero−valent iron (nZVI) is a strong reductant, particle aggregation, surface passivation, and inefficient interfacial electron transfer limit its reactivity toward ClO4−. Here, a mesoporous nZVI@Mg(OH)2 core–shell−like composite was fabricated by a one−step liquid−phase in situ deposition strategy to couple substrate accessibility with interfacial electron transfer. At a nominal Mg(OH)2/nZVI mass ratio of 10%, the Mg(OH)2−modified composite showed substantially reduced particle aggregation and increased the BET specific surface area from 4.57 to 67.29 m2·g−1 and the pore volume from 0.0242 to 0.2542 cm3·g−1. The hydroxylated Mg(OH)2 interface may additionally favor local ClO4− accumulation under acidic−to−near−neutral conditions. Under benchmark conditions, the system removed 98.37% of 10 mg·L−1 ClO4− from the aqueous phase within 48 h. The reaction also showed an apparent activation energy of 50.96 ± 6.04 kJ·mol−1. XRD, Raman, and XPS analyses showed progressive Fe0 consumption and the development of a Fe3O4−dominated crystalline reaction layer with a more oxidized and hydroxylated Fe(III)−rich outer region, providing independent evidence for a strongly reducing and dynamically reconstructed Fe−containing interface. Electrochemical measurements revealed a substantially more negative open−circuit potential for nZVI@Mg(OH)2, while equivalent−circuit fitting showed that the total polarization resistance decreased from 15.21 to 10.78 kΩ relative to bare nZVI, consistent with a more electrochemically accessible interface. In situ OCP measurements further showed an immediate electrochemical response upon ClO4− addition. Together with TBA scavenging and Fe2+ control experiments, these results support a predominantly heterogeneous interfacial transformation process and are consistent with a major contribution from direct interfacial electron transfer. The enhanced reactivity is attributed to the coupling of improved substrate accessibility with an electronically accessible, low−resistance Fe−containing interface. This work provides a mechanistic basis for the interfacial design of Fe−based materials with coordinated mass−transport and electron−transfer characteristics toward kinetically persistent oxyanions.
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BibTeX
@article{xu2026interface,
title = {{Interface Reconstruction of nZVI with a Mesoporous Mg(OH)2 Shell: Coupled Mass Transport and Interfacial Electron Transfer During Perchlorate Transformation}},
author = {Keke Xu and Yongkang Sun and Lichao Tan and Mingzhu Zhang and Wenming Pei and Ziyan Du and Jiqiang Jia and Xiaoyan Zhang and Jingjing Yun and Feng Ge and Lei Wang and Ningyuan Zhu},
journal = {Nanomaterials},
year = {2026},
month = oct,
doi = {10.3390/nano16211364},
url = {https://www.mdpi.com/2079-4991/16/21/1364},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Interface Reconstruction of nZVI with a Mesoporous Mg(OH)2 Shell: Coupled Mass Transport and Interfacial Electron Transfer During Perchlorate Transformation
AU - Keke Xu
AU - Yongkang Sun
AU - Lichao Tan
AU - Mingzhu Zhang
AU - Wenming Pei
AU - Ziyan Du
AU - Jiqiang Jia
AU - Xiaoyan Zhang
AU - Jingjing Yun
AU - Feng Ge
AU - Lei Wang
AU - Ningyuan Zhu
PY - 2026
DA - 2026/10/26
JO - Nanomaterials
DO - 10.3390/nano16211364
UR - https://www.mdpi.com/2079-4991/16/21/1364
AB - Perchlorate (ClO4−) is kinetically persistent in aqueous environments because of its highly symmetric tetrahedral structure and the high activation barrier for Cl−O bond cleavage. Although nanoscale zero−valent iron (nZVI) is a strong reductant, particle aggregation, surface passivation, and inefficient interfacial electron transfer limit its reactivity toward ClO4−. Here, a mesoporous nZVI@Mg(OH)2 core–shell−like composite was fabricated by a one−step liquid−phase in situ deposition strategy to couple substrate accessibility with interfacial electron transfer. At a nominal Mg(OH)2/nZVI mass ratio of 10%, the Mg(OH)2−modified composite showed substantially reduced particle aggregation and increased the BET specific surface area from 4.57 to 67.29 m2·g−1 and the pore volume from 0.0242 to 0.2542 cm3·g−1. The hydroxylated Mg(OH)2 interface may additionally favor local ClO4− accumulation under acidic−to−near−neutral conditions. Under benchmark conditions, the system removed 98.37% of 10 mg·L−1 ClO4− from the aqueous phase within 48 h. The reaction also showed an apparent activation energy of 50.96 ± 6.04 kJ·mol−1. XRD, Raman, and XPS analyses showed progressive Fe0 consumption and the development of a Fe3O4−dominated crystalline reaction layer with a more oxidized and hydroxylated Fe(III)−rich outer region, providing independent evidence for a strongly reducing and dynamically reconstructed Fe−containing interface. Electrochemical measurements revealed a substantially more negative open−circuit potential for nZVI@Mg(OH)2, while equivalent−circuit fitting showed that the total polarization resistance decreased from 15.21 to 10.78 kΩ relative to bare nZVI, consistent with a more electrochemically accessible interface. In situ OCP measurements further showed an immediate electrochemical response upon ClO4− addition. Together with TBA scavenging and Fe2+ control experiments, these results support a predominantly heterogeneous interfacial transformation process and are consistent with a major contribution from direct interfacial electron transfer. The enhanced reactivity is attributed to the coupling of improved substrate accessibility with an electronically accessible, low−resistance Fe−containing interface. This work provides a mechanistic basis for the interfacial design of Fe−based materials with coordinated mass−transport and electron−transfer characteristics toward kinetically persistent oxyanions.
SN - 2079-4991
ER -