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Sulfidated zero valent iron (ZVI) is a popular material for the reductive degradation of halogenated organic pollutants. Simple and economic synthesis of this material is highly demanded. In this study, sulfidated micro/nanostructured ZVI (MNZVI) particles were prepared by simply heating MNZVI particles and sulfur elements (S 0 ) in pure water (50℃). The iron oxides on the surface of MNZVI particles were conducive to sulfidation reaction, indicating the formation of iron-sulphide minerals (FeS x ) on the surface of MNZVI particles might not be from the direct reaction of Fe 0 with S 0 (Fe 0 and S 0 acted as reductant and oxidant, respectively). As an important reductant, hydrogen atom (H•) can be generated from the reduction of H + by MNZVI particles and participate in the formation of FeS x . Quenching experiment and cyclic voltammetry analysis proved the existence of H• on the surface of MNZVI particles. DFT calculation found that the potential barrier of H•/S 0 and Fe 0 /S 0 were 1.91 and 7.24 eV, respectively, indicating that S 0 would preferentially react with H• instead of Fe 0 . The formed H• can quickly react with S 0 to generate hydrogen sulfide (H 2 S), which can further react with iron oxides such as α-Fe 2 O 3 on the surface of MNZVI particles to form FeS x . In addition, the H 2 partial pressure in water significantly affected the amount of H• generated, thereby affecting the sulfidation efficiency. For TCE degradation, as the sulfur loading of sulfidated MNZVI particles increased, the contribution of H• significantly decreased while the contribution of direct electron transfer increased. This study provided new insights into the synthesis mechanism of sulfidated ZVI in water., Competing Interests: 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., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Biogenic sulfidation of zero-valent iron (ZVI) using sulfate reducing bacteria (SRB) has shown enhanced dechlorination rates comparable to those produced by chemical sulfidation. However, controlling and sustaining biogenic sulfidation to enhance in situ dechlorination are poorly understood. Detailed interactions between SRB and ZVI were examined for 4 months in column experiments under enhanced biogenic sulfidation conditions. SRB proliferation and changes in ZVI surface properties were characterized along the flow paths. The results show that ZVI can stimulate SRB activity by removing excessive free sulfide (S 2- ), in addition to lowering reduction potential. ZVI also hinders downgradient movement of SRB via electrostatic repulsion, restricting SRB presence near the upgradient interface. Dissolved organic carbon (e.g., >2.2 mM) was essential for intense biogenic sulfidation in ZVI columns. The presence of SRB in the upgradient zone appeared to promote the formation of iron polysulfides. Biogenic FeS x deposition increased the S content on ZVI surfaces ∼3-fold, corresponding to 3-fold and 2-fold improvements in the trichloroethylene degradation rate and electron efficiency in batch tests. Elucidation of SRB and ZVI interactions enhances sustained sulfidation in ZVI permeable reactive barrier.

The solid-solid reaction of microscale zero-valent iron (mZVI) with elemental sulfur (S 0 ) in water can form sulfidated mZVI (S-mZVI) with high reactivity and selectivity. However, the inherent passivation layer of mZVI hinders the sulfidation. In this study, we demonstrate that ionic solutions of Me-chloride (Me: Mg 2+ , Ca 2+ , K + , Na + and Fe 2+ ) can accelerate the sulfidation of mZVI by S 0 . The S 0 with S/Fe molar ratio of 0.1 was fully reacted with mZVI in all solutions to form unevenly distributed FeS species on S-mZVIs as confirmed by SEM-EDX and XANES characterization. The cations depassivated the mZVI surface by driving the proton release from the surface site (FeOH) and resulting in localized acidification. The probe reaction test (tetrachloride dechlorination) and open circuit potential (E OCP ) measurement demonstrated that Mg 2+ was most efficient in depassivating the mZVI and therefore promoting sulfidation. The decrease of surface proton for hydrogenolysis on the S-mZVI synthesized in MgCl 2 solution also inhibited the formation of cis-1,2-dichloroethylene by 14-79% compared to other S-mZVIs during trichloroethylene dechlorination. In addition, the synthesized S-mZVIs exhibited the highest reduction capacity reported so far. These findings provide a theoretical basis for the facile on-site sulfidation of mZVI by S 0 with cation-rich natural waters for sustainable remediation of contaminated sites., Competing Interests: 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., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Knowledge of the fate and transport of nanoscale zero-valent iron (nZVI) in saturated porous media is crucial to the development of in situ remediation technologies. This work systematically compared the retention and transport of carboxymethyl cellulose (CMC) modified nZVI (CMC-nZVI) and sulfidated nZVI (CMC-S-nZVI) particles in saturated columns packed with quartz sand of various grain sizes and different surface metal oxide coatings. Grain size reduction had an inhibitory effect on the transport of CMC-S-nZVI and CMC-nZVI due to increasing immobile zone deposition and straining in the columns. Metal oxide coatings had minor effect on the transport of CMC-S-nZVI and CMC-nZVI because the sand surface was coated by the free CMC in the suspensions, reducing the electrostatic attraction between the nZVI and surface metal oxides. CMC-S-nZVI displayed greater breakthrough (C/C 0  = 0.82-0.90) and higher mass recovery (84.9%-89.3%) than CMC-nZVI (C/C 0  = 0.70-0.80 and mass recovery = 70.9%-79.6%, respectively) under the same experimental conditions. A mathematical model based on the advection-dispersion equation simulated the experimental data of nZVI breakthrough curves very well. Findings of this study suggest sulfidation could enhance the transport of CMC-nZVI in saturated porous media with grain and surface heterogeneities, promoting its application in situ remediation., Competing Interests: 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., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The application of lignin derivative as modifier is an economical and efficient approach to improve the reactivity of raw material towards pollutant removal. In this study, lignosulfonate modified zero valent iron (LS-ZVI) was firstly prepared by ball-milling method and utilized for Cr(VI) removal under different conditions. The comparative experiments showed that lignosulfonate modification could significantly enhance the Cr(VI) removal by ZVI from <10 % to 100 % within 90 min reaction. Compared to ZVI, the specific surface area of LS-ZVI increased 3.4 times and surface Fe(0) content increased from 3.4 % to 10.5 % due to the surface erosion, resulting in the high-efficient Cr(VI) removal. Solution and solid-phase analyses indicated that Fe(0) played dominated role and generated Fe(II) involved in Cr(VI) removal process, which mainly included rapid adsorption, reduction and co-precipitation. Batch experiments revealed that lower pH conditions were beneficial for Cr(VI) removal and the effect of co-existing ions (Ca 2+ , Mg 2+ , NO 3 - , Cl - , and SO 4 2- ) was negligible except the inhibitory effect of NO 3 - . Moreover, LS-ZVI also exhibited excellent removal performance for Ni(II), Zn(II), and Cd(II) with removal efficiency beyond 96.6 %. Overall, this work provides a feasible approach for enhancing the reactivity of commercial ZVI in the treatment of heavy metal pollution., Competing Interests: 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., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Modulating the electronic structure of electrode materials at atomic level is the key to controlling electrodes with outstanding rate capability. On the basis of modulating the iron cationic vacancies (IV) and electronic structure of materials, we proposed the method of preparing graphdiyne/ferroferric oxide heterostructure (IV‐GDY‐FO) as anode materials. The goal is to motivate lithium‐ion batteries (LIBs) toward ultra‐high capacity, superior cyclic stability, and excellent rate performance. The graphdiyne is used as carriers to disperse Fe3O4 uniformly without agglomeration and induce high valence of Fe with reducing the energy in the system. The presence of Fe vacancy could regulate the charge distribution around vacancies and adjacent atoms, leading to facilitate electronic transportation, enlarge the lithium‐ion diffusion, and decrease Li+ diffusion barriers, and thus displaying significant pseudocapacitive process and advantageous lithium‐ion storage. The optimized electrode IV‐GDY‐FO reveals a capacity of 2084.1 mAh g−1 at 0.1 C, superior cycle stability and rate performance with a high specific capacity of 1057.4 mAh g−1 even at 10 C. [ABSTRACT FROM AUTHOR]

Uranium anomalies were discovered in ferruginous sandstone in the Khusayyayn Formation of the Wajid Group in southern Saudi Arabia. Based on field surveys, ground radiometric surveys, and chemical analysis, this paper summarizes the characteristics of the lithology and lithofacies of the ferruginous sandstone and analyzes the genetic mechanism of uranium concentration in ferruginous sandstone. Ferric iron basically exists in the form of Fe2O3 in ferruginous sandstone, with an average content of 28.95 wt.%. The formation period of the ferruginous sandstone occurred during the early synsedimentary and later diagenesis stages from the Carboniferous to the Devonian. The uranium anomaly is hosted in thin-bedded and lenticular ferruginous sandstone, with a uranium content ranging from 50 to 766 ppm. The average U-Ra equilibrium coefficient of ferruginous sandstone was 1.00, indicating that the uranium was weakly reformed after the uranium concentration. Ferric ions are closely related to uranium mineralization. The initial concentration of the uranium occurred during the deposition of the ferruginous sandstone. Most of the uranium was adsorbed by a ferric colloidal solution, and part of it was reduced by Fe2+, organic carbon, and sulfur in the uranium preconcentrated stage during the deposition of ferruginous sandstone. The uranium ore was superimposed, transformed, and concentrated due to the change in the pH environment in the early Neogene. [ABSTRACT FROM AUTHOR]

• A multi-stage Malmquist-Luenberger index model is constructed for the multiple production of iron and steel industry. • The proposed model can evaluate environmental total factor productivity (ETFP) growth of whole system and sub-process. • Technical regression of steel-making sub-process is the main source of restricting system ETFP growth. • The change of system ETFP varies greatly, being highest in the eastern region, and lowest in the western region. • Compared with the single-stage conventional MLPI, the multi-stage MLPI is smaller and has more discriminatory power. This paper develops a multi-stage Malmquist-Luenberger index (MLPI) model by considering the joint production of desirable and undesirable outputs in multiple production processes. The proposed approach not only evaluates the environmental total factor productivity (ETFP) growth of the whole system but also investigate the progress and regress of each sub-process, i.e., the iron-making sub-process and the steel-making sub-process. Driving factors of ETFP change are identified through multi-stage MLPI decomposition. With an application of the proposed model in China's 48 iron and steel enterprises over the period of 2009–2013, the validity of the proposed models has been demonstrated. Moreover, this study explores the regional difference analysis of system and multi-stage ETFP among 31 provinces in eastern, central and western regions. Results show that the ETFP of system, iron-making sub-process and steel-making sub-process experienced increase annually, the most important finding is that the environmental efficiency increase is the most critical driving factor in promoting ETFP growth. Technical regression of steel-making sub-process is the main source of restricting system ETFP growth. In addition, the change of system ETFP varies greatly in different regions, being highest in the eastern region, and lowest in the western region. Compared with the single-stage conventional MLPI, the multi-stage MLPI is smaller and has more discriminatory power. [ABSTRACT FROM AUTHOR]

The reductive capacity of zero valent iron (ZVI) is extremely restricted by the surface passivation. To address this issue, ball-milling lignosulfonate modified ZVI (LS-ZVI) was prepared and used to determine the reactivity, electron utilization efficiency and application feasibility towards nitrobenzene (ArNO 2) removal. The results showed that LS-ZVI could completely remove ArNO 2 within 40 min with aniline conversion percentage of ∼95%, while ArNO 2 reduction by ZVI was negligible within 180 min. Electrochemical evidence, H 2 production, and characterization analysis collectively illuminated that the enhanced ArNO 2 reduction by LS-ZVI was attributed to the increased Fe0 exposure that endowed it with excellent electron transfer ability. The inhibited H 2 production indicated that the electron utilization efficiency of LS-ZVI towards ArNO 2 was close to 100%. Moreover, ArNO 2 removal was slightly inhibited under higher solution pH. Except for the obvious inhibitory effect of high concentration NO 3 −, the effects of co-existing ions (Cl−, NO 3 −, SO 4 2−, Ca2+, and Mg2+) were little. The presence of Ni(II) had a negligible effect on ArNO 2 removal, while high concentration of Cd(II) and Cr(VI) could obviously inhibit ArNO 2 reduction. In addition, the excellent reusability of LS-ZVI and the complete ArNO 2 removal in groundwater suggested the feasibility of LS-ZVI in practical field remediation. [Display omitted] • Lignosulfonate modification significantly enhanced nitrobenzene removal by ZVI. • The increased Fe0 exposure endowed LS-ZVI with faster electron transfer ability. • Electrons from LS-ZVI was almost completely utilized for nitrobenzene reduction. • LS-ZVI exhibited excellent regeneration capacity towards nitrobenzene removal. • LS-ZVI could also completely remove nitrobenzene from groundwater. [ABSTRACT FROM AUTHOR]

In the conventional data envelopment analysis (DEA) window analysis, a decision-making unit (DMU) in each window is treated as different units in each period so that the evaluation for one unit is performed on different scales over time. This paper proposes a novel window analysis based on common weight across time (CWAT), which evaluates each unit in each window by its common scale independent of time. The model for obtaining common weights is described as linear programming. And the paper suggests the Malmquist productivity index (MPI) on CWAT, CWAT MPI, to analyze productivity change by inheriting the result of window analysis. The numerical experiments are illustrated to examine the validity of CWAT and MPI, and the result shows that the proposed method provides a new evaluation scale compared to previous studies. The proposed model is applied to evaluate the performance of China 45 iron and steel enterprises during 2009–2017. The energy and environmental efficiency are calculated using CWAT, and CWAT MPI analyzes the productivity change. • We study a DEA window analysis based on common weights. • The proposed DEA window is represented by linear programming. • We discuss the Malmquist index in the DEA window. • The MPI is the geometric mean of all indices calculated in individual windows. • The performance of the iron and steel enterprises is evaluated. [ABSTRACT FROM AUTHOR]

Under oxic environment, the corrosion of zero valent iron (ZVI) connects with its oxidation and adsorption capacity, but little is known about the effects of sulfidation on those processes of ZVI. To assess the oxidant production from ball-milling unsulfidated and sulfidated microscale ZVI (mZVIbm and S-mZVIbm), the transformation of benzoic acid (BA) to p-hydroxybenzoic acid (p-HBA) was used as the oxidation probe reaction. During the oxidation reaction, the concentration of p-HBA in S-mZVIbm/O 2 systems rapidly reached equilibrium (< 12 μM) within 40 min regardless of sulfur loading content, whereas it could gradually reach 26 μM in mZVIbm/O 2 system within 240 min despite the slower generation of p-HBA at initial stage. Combining with the characteristic analysis, the lower oxidation capacity of S-mZVIbm/O 2 system might be ascribed to the enhanced Fe(II) dissolution that caused a larger solution pH rise along with the loss of Fe(0) and FeS x sites and the formation of lepidocrocite, which was not beneficial for oxygen activation. Under the identical conditions such as material dosage and co-existing anions, the oxidation capacity of mZVIbm/O 2 system also exceeded S-mZVIbm/O 2 system. In addition, the comparative experiment of Zn2+ immobilization by S-mZVIbm and S-mZVIbm with or without BA was investigated. mZVIbm showed insignificant Zn2+ immobilization, whereas BA could enhance Zn2+ immobilization by S-mZVIbm due to the enhanced corrosion that could provide more adsorption sites. Overall, this work is valuable for assessing the oxidation capacity of S-mZVIbm/O 2 system and BA effect on heavy metal immobilization of S-mZVI in wastewater treatment. [Display omitted] • Sulfidation inhibited the final OH• amount of mZVIbm/O 2 system. • The loss of Fe0 and FeS x sites weakened oxidation capacity of S-mZVIbm/O 2 system. • Lepidocrocite was the major corrosion product of S-mZVIbm after oxidation reaction. • Benzoic acid could enhance the performance of S-mZVIbm for Zn2+ immobilization. [ABSTRACT FROM AUTHOR]

Goethite and pyrite are common iron minerals in oxic or anoxic environments, respectively, both minerals being major reservoirs for Nickel, a bio-essential element. Mineral transformation between goethite and pyrite is frequent owing to the alternation of oxic and anoxic conditions in sulfate-rich environments. This mineral transformation has been amply studied, but the effect of Ni on this transformation and its fate along it remain poorly understood. Sulfidation of Ni-free and Ni-containing (through adsorption or isomorphic substitution) goethites was thus studied experimentally by reacting goethite with dissolved S(-II) (molar Fe:S≈1:1). X-ray diffraction and associated Rietveld refinement, thermogravimetric analysis, scanning/transmission electron microscopy, X-ray absorption spectroscopy, and wet chemistry were used to monitor mineralogical evolutions and unravel Ni association with reaction products. After 44 days of sulfidation, about half of initial goethite converted to iron sulfides: thermodynamically stable pyrite (67%–93%) with minor contents of mackinawite (2%–15%) and greigite (5%–25%). Although the overall content of iron sulfides formed was essentially independent of Ni presence, Ni hampered the conversion from metastable iron sulfides (i.e., mackinawite and greigite) to pyrite (67%–78% vs. 93%, in the presence and absence of Ni, respectively). Pyrite formation from metastable sulfide precursors yielded a uniform Ni distribution in newly formed pyrite, regardless of the initial Ni association with goethite. Although no Ni was released to solution during pyrite formation, Ni incorporation to pyrite results in an increased risk of release to the environment as iron sulfides will be oxidized when exposed to air and water in supergene environments, leading to highly acidic conditions favoring Ni solubility and mobility. [ABSTRACT FROM AUTHOR]

Polymer stabilization, exemplified by carboxymethyl cellulose (CMC), has demonstrated effectiveness in enhancing the transport of nanoscale zero-valent iron (nZVI). And, sulfidation is recognized for enhancing the reactivity and selectivity of nZVI in dechlorination processes. The influence of polymer stabilization on sulfidated nZVI (S-nZVI) with various sulfur precursors remains unclear. In this study, CMC-stabilized S-nZVI (CMC-S-nZVI) was synthesized using three distinct sulfur precursors (S2−, S 2 O 4 2−, and S 2 O 3 2−) through one-step approach. The antioxidant properties of CMC significantly elevated the concentration of reduced sulfur species (S2−) on CMC-S-nZVIs, marking a 3.1–7.0-fold increase compared to S-nZVIs. The rate of trichloroethylene degradation (k m) by CMC-S-nZVIs was observed to be 2.2–9.0 times higher than that achieved by their non-stabilized counterparts. Among the three CMC-S-nZVIs, CMC-S-nZVI Na2S exhibited the highest k m. Interesting, while the electron efficiency of CMC-S-nZVIs surged by 7.9–12 times relative to nZVI, it experienced a reduction of 7.0–34% when compared with S-nZVIs. This phenomenon is attributed to the increased hydrophilicity of S-nZVI particles due to CMC stabilization, which inadvertently promotes the hydrogen evolution reaction (HER). In conclusion, the findings of this study underscores the impact of CMC stabilization on the properties and dechlorination performance of S-nZVI sulfidated using different sulfur precursors, offering guidance for engineering CMC-S-nZVIs with desirable properties for contaminated groundwater remediation. • S precursors tuned the S species formed on one-step CMC-stabilized S-nZVI. • CMC stabilization enhanced particle reactivity by retaining more reduced S species on particle surface. • CMC stabilization lowered electron efficiency by increasing particle hydrophilicity. • CMC-S-nZVI synthesized via Na 2 S possessed the highest reactivity and electron efficiency. [ABSTRACT FROM AUTHOR]

Ball milling is an effective technique to not only activate and reduce the size of commercial microscale zero valent iron (mZVI) but also to mechanochemically sulfidate mZVI. Yet, little is known about the difference between how chlorinated ethenes (CEs) interact with ball milled mZVI (mZVIbm) and mechanochemically sulfidated mZVI (S-mZVIbm). We show that simple ball milling exposed the active Fe0 sites, while mechanochemical sulfidation diminished Fe0 sites and meanwhile increased S2- sites. Mechanochemical sulfidation with [S/Fe] dosed increased from 0 to 0.20 promoted the particle reactivity most for TCE dechlorination (∼14-fold), followed by PCE and 1,1-DCE while it diminished the reactivity for trans -DCE (∼0.4-fold), cis -DCE (∼0.02-fold) and VC (∼0.002-fold) compared to simple ball milling. Sulfidation also improved the electron efficiency of CE dechlorination, except for cis -DCE and VC. The k SA of cis -DCE, VC and trans -DCE dechlorination positively correlated with surface Fe0 content, suggesting their dechlorination was mainly mediated by Fe0 site or reactive atomic hydrogen. The k SA of TCE dechlorination positively correlated with surface S2- content and the dechlorination mainly occurred on S2- sites via direct electron transfer. Increased sulfidation favored direct electron transfer mechanism. The k SA of PCE and 1,1-DCE was not dependent on either parameter and their dechlorination was equally achieved through either mechanism. [Display omitted] • Chlorinated ethene (CE) reduction by ball milled mZVIbm and S-mZVIbm were compared. • Sulfidation promoted dechlorination of TCE most but inhibited that of cis -DCE, VC. • Sulfidation improved the selectivity of CEs dechlorination except cis -DCE and VC. • Surface Fe0 content or atomic hydrogen mediates cis -DCE, VC, trans -DCE degradation. • TCE dechlorination is controlled by FeS sites or direct electron transfer. [ABSTRACT FROM AUTHOR]

[Display omitted] • CMC-S-nZVI synthesized by two methods can effectively dechlorinate soil-sorbed TCE. • CMC, a common nZVI stabilizer, can facilitate release of TCE from soils. • Soil particles promoted iron corrosion through taking Fe2+ from CMC-S-nZVI surface. • Soil particles blocked the CMC-S-nZVI surface during extended reactions. Carboxymethyl cellulose stabilized and sulfidated nano zero-valent iron (CMC-S-nZVI) can efficiently degrade trichloroethene (TCE) in water. However, little is known about the interaction between CMC-S-nZVI and TCE in soils. Here we studied the effects of two soils, a sandy (LY) and a sandy-loamy soil (DXAL), on TCE dechlorination by two types of CMC-S-nZVI particles. Continuous dechlorination of soil-sorbed TCE was observed for up to 96 h. LY and DXAL soil sorption suppressed 24-h dechlorination by 5–16 % and 25–51 %, respectively, although CMC significantly enhanced TCE release from the soils. Soil clay minerals, including Fe/Mn oxides and organic matter, promoted iron corrosion during the initial stage (< 8 h and < 2 h for the two particle types) through uptake of Fe2+ from the CMC-S-nZVI surface, but inhibited corrosion and TCE dechlorination at the later stage by blocking surface reaction sites, thereby hindering electron transfer. The dual effects of soil were more evident in DXAL, due to its higher content of clays and organic matter. Our findings show that CMC-S-nZVI can effectively dechlorinate soil-sorbed TCE, but reductant demand and the blocking effect from the soil should be considered to optimize engineering designs at TCE-contaminated sites. [ABSTRACT FROM AUTHOR]

While it has been recognized that sulfidation can effectively improve the reactivity of microscale zero valent iron (mZVI), there is limited understanding of nitrobenzene (ArNO 2) removal by sulfidated mZVI. To understand the reduction capacity and pathway of ArNO 2 by sulfidated mZVI, ball-milling sulfidated mZVI (S-mZVIbm) with different S/Fe molar ratios (0–0.2) was used to conduct this experiment. The results showed that sulfidation could efficiently enhance ArNO 2 removal under iron-limited and iron excess conditions, which was attributed to the presence of FeS x sites that could provide higher Fe(0) utilization efficiency and stronger passivation resisting for S-mZVIbm. The optimum ArNO 2 reduction could be obtained by S-mZVIbm with S/Fe molar ratio at 0.1, which could completely transform ArNO 2 to aniline (ArNH 2) with a rate constant of 4.36 × 10−2 min−1 during 120-min reaction. FeS x phase could act as electron transfer sites for ArNO 2 reduction and it could still be reserved in S-mZVIbm after reduction reaction. The product distribution indicated that sulfidation did not change the types of reduction products, while the removal of ArNO 2 by S-mZVIbm was a step-by-step reduction progress along with the adsorption of ArNH 2. In addition, a faster reduction of ArNO 2 in groundwater/soil system further demonstrated the feasibility of S-mZVIbm in the real field remediation. [Display omitted] • Sulfidation significantly enhanced nitrobenzene removal by mZVIbm. • Fe(0) utilization of S-mZVIbm for nitrobenzene reduction was higher than that of mZVIbm. • FeS x phase acted as electron transfer sites for nitrobenzene reduction and still reserved after reaction. • Nitrobenzene removal by S-mZVIbm included a multi-step reduction process and adsorption of aniline. • S-mZVIbm exhibited a faster nitrobenzene removal in groundwater/soil system. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile strategy for anion defect-rich electrocatalyst is proposed in this study. • The catalysts exhibited excellent OER, HER, and overall water splitting catalytic performance. • Introduction of Fe3+ and anion defects could reduce the energy barrier of intermediate. Interfacial electronic structure regulation has been shown to be beneficial for a variety of electrocatalytic reactions. However, integrating foreign species into anion vacancy defect electrocatalysts, and investigating their interfacial electron structure and synergistic catalytic effect are still somewhat controversial. Herein, Fe 2 O 3 /NiSe 2 and Fe 2 O 3 /Ni 3 S 2 heterostructures catalysts with abundant anion defects (Se, S) were constructed through an efficient spatial combination of primary hydroxide nanosheets. The Fe 2 O 3 /NiSe 2 and Fe 2 O 3 /Ni 3 S 2 catalysts exhibited outstanding electrocatalytic activities, as shown by the overpotentials of 200 mV at 100 mA cm−2 for OER, and 60 mV at 10 mA cm−2 for HER, respectively. The Fe 2 O 3 /NiSe 2 (anode)‖Fe 2 O 3 /Ni 3 S 2 (cathode) device accelerated water splitting at 1.54 V with 10 mA cm−2, surpassing the integrated couple of Pt and Ir-based oxide (1.57 V). The chemical valence state, combined with DFT calculations, revealed that interface engineering and anion defects could modulate the electronic structures of the Fe 2 O 3 modified NiSe 2 and Ni 3 S 2 catalysts, reduce the energy barrier of intermediate, and therefore dramatically improve their catalytic performances. This work not only presents a universal strategy for the construction of active and durable electrocatalyst with abundant anion defects, but also provides a new way for the rational design of novel nanostructure for electrocatalytic applications. [ABSTRACT FROM AUTHOR]