Spherical Electron Research Articles

An Angstrom-Scale Protective Skin Grown In Situ on Perovskite Oxide to Enhance Stability in Water.

The utilization of perovskite oxide as a catalyst for aqueous reactions is promising but challenging in stability. Here, we propose an in situ growth strategy that constructs an ultrathin protective skin on the Sr0.9Fe0.81Ta0.09Ni0.1O3-δ perovskite surface and thus effectively solves the stability issue. Using a spherical aberration-corrected transmission electron microscope, we observe the coexistence of an angstrom-scale (~7 Å) Fe2O3 protective skin and FeNi alloy nanoparticles. A number of alloy nanoparticles grow along with the skin and uniformly take root on the skin surface. Such a hierarchical structure can reconstruct the surface electronic structure and suppress the ion leaching of perovskite oxide in water. Benefiting from this unique structure, the catalyst has experienced a substantial increase (800 h, more than three orders of magnitude) in its stable operation time in water (for example, in a hydrogen evolution reaction). These results provide valuable insight into solid-solid phase transitions and have substantial implications for using structural defects at surfaces to modulate mass transport and transformation kinetics. Our strategy is sufficiently simple and can be used to subtly manipulate the catalyst structures to improve the performance of perovskite-based catalysts and potentially other oxide catalysts for a wide range of reactions.

Simultaneously Enhanced Low Temperature Li+ Transport Kinetics and Crystal Stability of Nb1.94Mo0.06O5@C Anode Induced by Distorted NbO6 Octahedron

AbstractThe electrochemical performances of lithium‐ion batteries (LIBs) will be significantly degraded under low‐temperature conditions, which restricts their wide application in cold environments. Herein, the low‐temperature transport kinetics of a novel Nb1.94Mo0.06O5@C nanocomposite anode is accelerated greatly via engineering the microstructure and NbO6 octahedron. The detailed crystallographic features are characterized by using synchrotron radiation, spherical electron microscope, and density functional theory simulation methods. Both experimental and simulation analysis suggest that Mo6+ preferentially replaces Nb5+ in the regular octahedral location and distorts the NbO6 octahedron, resulting in a widened c‐axis spacing and a lowered ion diffusion barrier. Coupled with the enhanced electronic conductivity derived from surface carbon layer, Nb1.94Mo0.06O5@C anode exhibits an enhanced charge transfer process, improved Li+ diffusion kinetics, pronounced pseudo‐capacitance process, and excellent low temperature capacity. Furthermore, in situ X‐ray diffraction and ex situ electron microscope elucidate that the structural evolution of Nb1.94Mo0.06O5@C is highly reversible, unveiling its excellent cycling stability. The full cell assembled with LiNi0.6Co0.2Mn0.2O2 cathode demonstrates excellent practicality. This study reveals the critical role of distorting NbO6 octahedron and expanding crystal spacing in facilitating rapid Li+ diffusion and enhancing charge storage performance of Nb2O5 at low temperatures.

Control of Grain Boundary Formation in Atomically Resolved Nanocrystalline Carbon Monolayers: Dependence on Electron Energy

Abstract In this study, we explore the dynamics of grain boundaries in nanocrystalline carbon monolayers, focusing on their variation with electron beam energy and electron dose rate in a spherical and chromatic aberration-corrected transmission electron microscope. We demonstrate that a clean surface, a high-dose rate, and a 60 keV electron beam are essential for precise local control over the dynamics of grain boundaries. The structure of these linear defects has been evaluated using neural network-generated polygon mapping.

Improving Catalytic Performance via the Synergy of Tensile Lattice Strain and Plasmonic Enhancement in Defective AuPd@Pd Short Nanowires.

The synthesis of bimetallic nanocatalysts with strained crystal lattices has attracted considerable interest. This is because, beyond the electronic structure modifications realized through elemental doping, the strain effect offers an extra mechanism to fine-tune the electronic structures, thereby possibly improving the catalytic performances. We present a method for constructing defective AuPd@Pd short nanowires, achieved through a controlled galvanic replacement reaction between short AuCu nanowires and Pd precursors. Advanced structural analyses using spherical aberration-corrected transmission electron microscopy (AC-TEM) validated the expanded crystal lattice on the nanowire surface and also demonstrated pronounced plasmonic absorption in the UV-vis region. Leveraging both plasmonic absorption and strain effects, the AuPd@Pd short nanowires displayed a higher apparent rate constant compared to Pd nanoparticles. Integrating molecular dynamic simulations with density functional theory calculations revealed that the tensile strain on AuPd@Pd short nanowires benefited the catalytic activity by elevating the d-band center, thereby intensifying the adsorption of p-nitrophenol. The current research introduces a unique method for synthesizing noble metal nanocrystals with specific dimensions and elucidates the rational development of high-performance plasmonic nanocatalysts through synergistic exploitation of the beneficial strain effect.

Mn-Induced microstructural stabilization and mechanical strengthening in Cu-Ni-Sn alloys: A mechanistic exploration

The exploration of the mechanical properties and microstructural evolution in Cu-9Ni-6Sn-XMn (X = 0, 0.1, 0.5, 1.0 wt%) alloys that were aged at 350 °C for various durations has been conducted. Spherical aberration-corrected scanning transmission electron microscopy (AC-STEM) was utilized to characterize the nanoscale phases at the atomic scale. The results indicated that the hardness and tensile strength of the Cu-9Ni-6Sn alloy were significantly enhanced with the addition of Mn. When the Mn content was 0.1 wt % and the aging time was 720 min, the hardness and tensile strength of the alloy reached 394 HV and 883 MPa, respectively. These values were 25 HV and 84 MPa higher than those of the Mn-free alloy. The Cu-9Ni-6Sn alloy exhibits the coexistence of nanoscale D022/L12 ordered phases throughout the aging process, which subsequently transition into discontinuous precipitation (DP). Mn effectively prevented the coarsening of the D022/L12 ordering phases during the aging process, which may be the key factor in enhancing the strengthening effect of the alloy. It was observed that no secondary phase related to Mn was formed, as Mn was completely dissolved in the alloy. Furthermore, Mn segregated at the DP at the later stages of aging, which was attributed to the negative mixing enthalpy between Sn-Mn and Ni-Mn. The suppression of DP was related to the enhanced stability of the D022/L12 ordering phase. These results are anticipated to provide valuable guidance for the production and application of Cu-Ni-Sn alloys.

Synergistic Active Heterostructure Design for Enhanced Two Electron Oxygen Reduction via Chemical and Electrochemical Reconstruction of Heterosulfides.

Transition metal sulfides, particularly heterostructures, represent a promising class of electrocatalysts for two electron oxygen reduction (2e- ORR), however, understanding the dynamic structural evolution of these catalysts during alkaline ORR remains relatively unexplored. Herein, NiS2/In2.77S4 heterostructure was synthesized as a precatalyst and through a series of comprehensive ex situ and in situ characterizations, including X-ray absorption spectroscopy, Raman spectroscopy, transient photo-induced voltage measurements, electron energy loss spectroscopy, and spherical aberration-corrected electron microscopy, it was revealed that nickel/indium (oxy)hydroxides (NiOOH/In(OH)3) could be evolved from the initial NiS2/In2.77S4 via both electrochemical and chemical-driven methods. The electrochemical-driven phase featured abundant bridging oxygen-deficient [NiO6]-[InO6] units at the interfaces of NiOOH/In(OH)3, facilitating a synergistic effect between active Ni and In sites, thus enabling an enhanced alkaline 2e- ORR capability than that of chemical-driven process. Remarkably, electrochemically induced NiOOH/In(OH)3 exhibited exceptional performance, achieving H2O2 selectivity of >90 % across the wide potential window (up to 0.4 V) with a peak selectivity of >99 %. Notably, within the three-electrode flow cell, a current density of 200 mA cm-2 was sustained over 20 h, together with an impressive Faradaic efficiency of ~90 % during the whole cycle process.

Obtaining in-situ reacted Fe–W–Ni–Cr–Cu high-entropy alloy within the interlayer of dissimilar Cf/SiC-GH3536 joint by designing non-high-entropy Cu–Ti–W composite filler

In aerospace applications, the development of high-entropy alloys (HEAs) filler is an effective strategy to obtain reliable Cf/SiC nozzles and GH3536 thrust chambers components. Considering the high costs and extended preparation times with HEA fillers, utilizing non-HEA fillers to generate HEAs within brazing seam offers significant advantages. This study successfully joined Cf/SiC with GH3536 using a non-HEA Cu–Ti–W composite filler that facilitated the in-situ formation of Fe–W–Ni–Cr–Cu HEA during the brazing process. Furthermore, the formation and accompanying martensite phase transformation were revealed. The microstructure characteristic of W reinforcements/HEA/Cu(s,s) was ultimately formed in the brazing seam. The atomic structure of the HEA, confirmed to be hexagonal close-packed, was elucidated using spherical aberration-corrected transmission electron microscopy. Additionally, a martensite phase transformation was observed in the HEA, involving two adjacent layers of (0 0 0 1) atomic planes that sheared and move a3 distance alon g [10–10] in opposite directions, resulting in the formation of M-HEA. The inclusion of HEA and M-HEA in the Cf/SiC-GH3536 joint, brazed with Cu–Ti–W composite filler, increased its shear strength to 84.8 MPa, which was 2.15 times higher than that of joints without the W reinforcements. This study offers new insights into the design of composite fillers and the application of HEAs.

In Situ Formation of SnSe2/SnSe Vertical Heterostructures toward Polarization Selectable Band Alignments.

2D van der Waals (vdW) layered semiconductor vertical heterostructures with controllable band alignment are highly desired for nanodevice applications including photodetection and photovoltaics. However, current 2D vdW heterostructures are mainly obtained via mechanical exfoliation and stacking process, intrinsically limiting the yield and reproducibility, hardly achieving large-area with specific orientation. Here, large-area vdW-epitaxial SnSe2/SnSe heterostructures are obtained by annealing layered SnSe. These in situ Raman analyses reveal the optimized annealing conditions for the phase transition of SnSe to SnSe2. The spherical aberration-corrected transmission electron microscopy investigations demonstrate that layered SnSe2 epitaxially forms on SnSe surface with atomically sharp interface and specific orientation. Optical characterizations and theoretical calculations reveal valley polarization of the heterostructures that originate from SnSe, suggesting a naturally adjustable band alignment between type-II and type-III, only relying on the polarization angle of incident lights. This work not only offers a unique and accessible approach to obtaining large-area SnSe2/SnSe heterostructures with new insight into the formation mechanism of vdW heterostructures, but also opens the intriguing optical applications based on valleytronic nanoheterostructures.

A CeO2 (100) surface reconstruction unveiled by in situ STEM and particle swarm optimization techniques.

The reconstruction of the polar CeO2 (100) surface has been a subject of long-standing debates due to its complexity and the limited availability of experimental data. Herein, we successfully reveal a CeO2 (100)-(4 × 6) surface reconstruction by combining in situ spherical aberration-corrected scanning transmission electron microscopy, density functional theory calculations, and a particle swarm optimization-based algorithm for structure searching. We have further elucidated the stabilizing mechanism of the reconstructed structure, which involves the splitting of the filled Ce(4f) states and the mixing of the lower-lying ones with the O(2p) orbitals, as evidenced by the projected density of states. We also reveal that the surface chemisorption properties toward water molecules, an important step in numerous heterogeneous catalytic reactions, are enhanced. These insights into the distinct properties of ceria surface pave the way for performance improvements of ceria in a wide range of applications.

Hirshfeld atom refinement and dynamical refinement of hexagonal ice structure from electron diffraction data.

Reaching beyond the commonly used spherical atomic electron density model allows one to greatly improve the accuracy of hydrogen atom structural parameters derived from X-ray data. However, the effects of atomic asphericity are less explored for electron diffraction data. In this work, Hirshfeld atom refinement (HAR), a method that uses an accurate description of electron density by quantum mechanical calculation for a system of interest, was applied for the first time to the kinematical refinement of electron diffraction data. This approach was applied here to derive the structure of ordinary hexagonal ice (Ih). The effect of introducing HAR is much less noticeable than in the case of X-ray refinement and it is largely overshadowed by dynamical scattering effects. It led to only a slight change in the O-H bond lengths (shortening by 0.01 Å) compared with the independent atom model (IAM). The average absolute differences in O-H bond lengths between the kinematical refinements and the reference neutron structure were much larger: 0.044 for IAM and 0.046 Å for HAR. The refinement results changed considerably when dynamical scattering effects were modelled - with extinction correction or with dynamical refinement. The latter led to an improvement of the O-H bond length accuracy to 0.021 Å on average (with IAM refinement). Though there is a potential for deriving more accurate structures using HAR for electron diffraction, modelling of dynamical scattering effects seems to be a necessary step to achieve this. However, at present there is no software to support both HAR and dynamical refinement.

Spectroscopic and modeling approaches of arsenic (III/V) adsorption onto Illite

Illite plays an essential role in arsenic (As) transportation in the subsurface. Despite extensive investigations into As adsorption onto illite, debates persist due to the absence of direct evidence revealing the underlying processes. In this research, we conducted batch experiments and employed spherical aberration-corrected scanning transmission electron microscope, X-ray absorption spectroscopy, and density functional theory-based calculations to elucidate the mechanisms for the adsorption of two major inorganic As species (As(III) and As(V)) onto illite. Experimental results indicate adsorption capacities of 0.251 and 0.667 μmol/g for As(III) and As(V) onto illite, respectively. As(III) adsorption occurs within 300 min, whereas As(V) is rapidly adsorbed within 500 min, after which it tends to stabilize. Both As species can adsorbed onto the basal surface via electrostatic forces, where cations act as a bridge, leading to specific-cation effects. Conversely, As adsorption onto the edge surface can be ascribed to inner-sphere complexes via As-O-Al bonds, causing a negatively shifted isoelectric point of illite. These mechanisms collectively account for the partially reversible adsorption and two-stage kinetics pattern. Finally, a process-based surface complexation model was developed to predict As adsorption onto illite, which includes the inner/outer-sphere complexation and monodentate/bidentate complexes.

Experimental confirmation of the linear relation between plasma current and external vertical magnetic field in EXL-50 spherical torus energetic electron plasmas

A three-fluid equilibrium plasma with bulk plasma and energetic electrons has been observed on the Xuanlong-50 (EXL-50) spherical torus, where the energetic electrons play a crucial role in sustaining the plasma current and pressure. In this study, the equilibrium of a multi-fluid plasma was investigated by analyzing the relationship between the external vertical magnetic field (B V), plasma current (I p), the poloidal ratio (β p) and the Shafranov formula. Remarkably, our research demonstrates some validity of the Shafranov formula in the presence of multi-fluid plasma in EXL-50 spherical torus. This finding holds significant importance for future reactors as it allows for differentiation between alpha particles and background plasma. The study of multi-fluid plasma provides a significant reference value for the equilibrium reconstruction of burning plasma involving alpha particles.

Surface reconstructed layer with bulk high-valence Mo doping to achieve long-life LiMn2O4 cathode material

Mo doping plays a striking role in the stability enhancement of LiMn2O4 cathode materials. However, the underlying microscopic mechanism is still unclear. Here, we elucidate that the relationship between the atomic position of Mo doping in LiMn2O4 and the stability enhancement of Mo-doped LiMn2O4 by utilizing the spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM). It exhibits that the part of Mo6+ ions occupy empty Mn 16c site to form a surface reconstructed layer of rock-salt like phase on the outermost surface and other Mo6+ ions dope into the Mn octahedral 16d sites to form LiMoxMn2-xO4 in bulk, which is beneficial for inhibiting the parasitic side reactions. Concomitantly, this dual modification of bulk structure and surface can significantly enhance electrode reversibility and Li+ diffusion. As a result, excellent long cycling stability of the as-designed optimal LiMo0.01Mn1.99O4 after 1500 cycles with 61.61 % capacity retention at 10 C (1 C = 148 mAh g−1) is presented, with an initial discharge capacity of 88.30 mAh g−1. Our research provides a clever approach for regulating the surface structure/bulk architecture in LiMn2O4 cathode materials.

Defect Density and Atomic Defect Recognition in the Middle Layer of a Trilayer MoS2 Stack.

Molybdenum disulfide (MoS2) is one of the most intriguing two-dimensional materials, and moreover, its single atomic defects can significantly alter the properties. These defects can be both imaged and engineered using spherical and chromatic aberration-corrected high-resolution transmission electron microscopy (CC/CS-corrected HRTEM). In a few-layer stack, several atoms are vertically aligned in one atomic column. Therefore, it is challenging to determine the positions of missing atoms and the damage cross-section, particularly in the not directly accessible middle layers. In this study, we introduce a technique for extracting subtle intensity differences in CC/CS-corrected HRTEM images. By exploiting the crystal structure of the material, our method discerns chalcogen vacancies even in the middle layer of trilayer MoS2. We found that in trilayer MoS2 the middle layer's damage cross-section is about ten times lower than that in the monolayer. Our findings could be essential for the application of few-layer MoS2 in nanodevices.

Enhancement of ionospheric heating effect by chemical release

The ionosphere can be artificially modified by employing ground-based high-power high-frequency electromagnetic waves to irradiate the ionosphere. This modification is achieved through the nonlinear interaction between the electromagnetic waves and the ionospheric plasma, leading to changes in the physical properties and structure of the ionosphere. The degree of artificial modification of the ionosphere is closely related to the heating energy density of high-frequency pump waves. Due to the high density of neutral constituents in the lower ionosphere and the high frequency of electron-neutral collisions, the energy of heating pump waves will be absorbed and attenuated during the penetration of the low ionosphere, seriously affecting the heating effect. This paper proposes a method to reduce the absorption of ionospheric heating pump waves by releasing electron attachment chemicals into low ionosphere to form a large-scale electron density hole. A model for mitigating pump waves absorption based on SF6 release is established, and the absorption at different frequencies is quantitatively calculated. The propagation characteristics of high-frequency signals in ionospheric holes are studied using a three-dimensional ray tracing method, and the results demonstrate that the chemical release method not only reduces the absorption attenuation of heating pump waves but also forms spherical electron density holes, which exhibit a focusing effect on the heating beam and enhance the heating effect. The results are of great significance for understanding the nonlinear interaction between electromagnetic wave and ionospheric plasma and improving the ionospheric heating efficiency.

2D Growth of BiSCl as Anisotropic Photodetector with Ultrahigh Responsivity and Detectivity

AbstractBiSCl, which shares the anisotropic chain‐like lattice configuration with the BiVXVIYVII (XS, Se; YCl, Br, I) family displays high photoelectric conversion efficiency in the UV–vis wavelength region. The current difficulty in 2D growth restricts the investigation of device performance and further integration. Herein, an epitaxial growth strategy for 2D BiSCl is proposed based on the principle of sharing a chloridion layer at the BiSCl/BiOCl interface. The interfacial atomic arrangement is carefully revealed using atomic resolved AC‐TEM(Spherical Aberration High Transmission Electron Microscope) and demonstrated by calculations based on density functional theory. Benefiting from its compatibility with PS‐assisted large‐scale transfer technology, the photoelectric performance is evaluated by constructing a standard symmetrical photoconductor and Graphene‐BiSCl Schottky junction device. High responsivity (1.71 × 104 A W−1) and detectivity (5.9 × 1016. Jones) are achieved at 405 nm, and robustness is shown in a broadband spectrum, which manifested prominent anisotropic photoelectric behavior and great potential in weak‐light detection. These results elucidate the photoelectric applications of BiSCl semiconductors and the structural design of the BiVXVIYVII family.

Atomic-Resolution Interfacial Reaction Mechanism between Bi2Te3-Based Alloys and Ni Electrodes.

Interdiffusion and solid-solid phase reaction at the interface between thermoelectric (TE) materials and the electrode critically influence interfacial transport properties and the overall energy conversion efficiency during service. Here, the microstructural evolution and diffusion mechanisms at the interfaces between the most widely used Bi2Te3-based TE materials, n-type Bi2Te2.7Se0.3 (BTS) and p-type Bi0.5Sb1.5Te3 (BST), and Ni electrodes were investigated at atomic resolution using spherical aberration-corrected scanning transmission electron microscopy (STEM). The BTS(0001)/Ni and BST(0001)/Ni interfaces were constructed by depositing Ni nanoparticles on mechanically exfoliated BTS and BST bulk materials and subsequent annealing. The interfacial reaction is initially dominated by Ni diffusion into the TE matrix to form NiAs-type NiM intermetallics, while Ni trans-quintuple-layer diffusion only occurs in Sb-rich BST. The Bi-rich BTS is more influenced by the Ni-Te preferential reaction, resulting in NiM abnormal grain growth and the formation of tilted and rotated interfaces. Bi diffusion into the BTS matrix forms a Bi double layer at the interface or Bi2[Bi2(Te,Se)3] as the annealing temperature increases, while Bi diffusion into the Ni thin film greatly accelerates the interfacial reaction rate, as elucidated by in situ heating STEM. The results provide essential structural details to understand and prevent the degradation of TE device performance.

Improvement of chemical mechanical polishing performance by introducing N–Si bond via external coating of cerium oxide with ZIF-8

Cerium oxide (CeO2) nanoparticles are widely used as abrasives in chemical mechanical polishing (CMP), an essential process for obtaining Si wafers with excellent surface quality. While CeO2 nanoparticles form Ce–O–Si bonds, which exhibit good CMP performance, their low activity results in a low removal rate. To address this issue, a two-step ultrasonic dispersion method was employed to prepare a uniform nuclear@shell CeO2@ZIF-8. The process of chemical bond generation in CMP was studied using spherical aberration-corrected transmission electron microscopy and X-ray photoelectron spectroscopy. In comparison to pure cerium oxide, the formation of Ce–O–Si bond was observed, and notably, the emergence of N–Si bond originating from the N of the ZIF-8 shell was identified. Coupled with the increased Ce3+ content, these developments enhanced CMP performance. The material removal rate (MRR) of the CeO2@ZIF-8 abrasives was 151.507 nm/min, which is 89.72 % higher than that of the pure CeO2 abrasives. Moreover, the surface roughness, as determined via AFM testing, was reduced to 0.231 nm within the confines of a 5.0 × 5.0 μm² region. Therefore, this study introduces a novel concept for CMP research by developing a CeO2@ZIF-8 compound abrasive to create a new N–Si bond.

Efficient catalytic degradation of carbamazepine using single-atom Ru-NiFe-LDH: Role of 1O2 and selective degradation

The targeted elimination of stubborn organic pollutants is crucial for human health and ecosystem well-being. Thanks to its exceptional efficiency and other benefits, peroxymonosulfate offers extensive potential for water treatment. However, realizing the practical application of this technology hinges on creating a high-efficiency catalyst. This study presents the fabrication of a monoatomic Ru catalyst through a straightforward hydrothermal approach. Synchrotron radiation and spherical electron microscopy were used to confirm the binding of monoatomic Ru to the NiFe-LDH (Layered Double Hydroxide, LDH) surface. Using a catalyst containing 0.77 wt% of single-atom Ru, 20 mg/L of Carbamazepine (CBZ) could be eliminated within 25 mins. With this, an impressive pseudo-first-order reaction rate constant of 0.118 min−1 was attained. The feasibility of the catalyst was evaluated in a column experimental reactor. The removal rate of 0.5 g of catalyst in wastewater containing 20 mg/L CBZ reached 100 %, demonstrating sustained operation for 720 mins. Ru-LDH/PMS system preferentially degrades carbamazepine, ciprofloxacin and other pollutants. This may be related to the structure and HOMO value of the pollutants and the active factors stimulated by Ru-LDH. Through a range of probe reactions and spectral analysis, it was determined that 1O2 played a pivotal role in pollutant degradation, closely linked to the presence of Ru.

Activation of iron oxide minerals in an aquifer by humic acid to promote adsorption of organic molecules

In aquifers, the sequestration and transformation of organic carbon are closely associated with soil iron oxides and can facilitate the release of iron ions from iron oxide minerals. There is a strong interaction between dissolved organic matter (DOM) and iron oxide minerals in aquifers, but the extent to which iron is activated by DOM exposure to active iron minerals in natural aquifers, the microscopic distribution of minerals on the surface, and the mechanisms involved in DOM molecular transformation are currently unclear. This study investigated the nonbiological reduction transformation and coupled adsorption of iron oxide minerals in aquifers containing DOM from both macro- and micro perspectives. The results of macroscopic dynamics experiments indicate that DOM can mediate soluble iron release during the reduction of iron oxide minerals, that pH strongly affects DOM removal, and that DOM is more efficiently degraded at low rather than high pH values, suggesting that a low pH is conducive to DOM adsorption and oxidation. Spherical aberration-corrected scanning transmission electron microscopy (SACTS) indicates that the reacted mineral surfaces are covered with large amounts of carbon and that dynamic agglomeration of iron, carbon, and oxygen occurs. At the nanoscale, three forms of DOM are found in the mineral surface agglomerates (on the surfaces, inside the surface agglomerates, and in the polymer pores). The microscopic organic carbon and iron mineral reaction patterns can form through oxidation reactions and selective adsorption effects. Fourier transform ion cyclotron resonance mass spectra indicate that both synergistic and antagonistic reactions occur between DOM and the minerals, that the release of iron is accompanied by DOM decomposition and humification, that large oxygen- and carbon-containing molecules are broken down into smaller oxygen- and carbon-containing compounds and that more molecules are produced through oxidation under acidic rather than alkaline conditions. These molecules provide adsorption sites for sediment, meaning that more iron can be released. Microscopic evidence for the release of iron was acquired. These results improve the understanding of the geochemical processes affecting iron in groundwater, the nonbiological transformation mechanisms that occur at the interfaces between natural iron minerals and organic matter, groundwater pollution control, and the environmental behavior of pollutants.