Comparative Study of the Impurity Effect on SnAgCu and SnZn Solder Joints with Electrodeposited Cu.

Sn-3Ag-0.5Cu (SAC305)- and Sn-9Zn-based alloys (Sn-Zn-X, X = Al, In) are lead-free solders used in the fabrication of solder joints with Cu metallization. Electroplating is a facile technology used to fabricate Cu metallization. However, the addition of functional additive molecules in the plating solution may result in impurity residues in the Cu electroplated layer, causing damage to the solder joints. This study investigates the impurity effect on solder joints constructed by joining various solder alloys to the Cu electroplated layers. Functional additives are formulated to fabricate high-impurity and low-impurity Cu electroplated samples. The as-joined solder joint samples are thermally aged at 120 °C and 170 °C to explore the interfacial reactions between solder alloys and Cu. The results show that the impurity effect on the interfacial reactions between SAC305 and Cu is significant. Voids are massively formed at the SAC305/Cu interface incorporated with a high impurity content, and the Cu6Sn5 intermetallic compound (IMC) grows at a faster rate. In contrast, the growth of the Cu5Zn8 IMC formed in the SnZn-based solder joints is not significantly influenced by the impurity content in the Cu electroplated layers. Voids are not observed in the SnZn-based solder joints regardless of the impurity content, indicative of an insignificant impurity effect. The discrepancy of the impurity effect is rationalized by the differences in the IMC formation and associated atomic interdiffusion in the SAC305- and SnZn-based solder joints.

Atomic Au3Cu Palisade Interlayer in Core@Shell Nanostructures for Efficient Kirkendall Effect Mediation.

Plasmonic Cu@semiconductor heteronanocrystals (HNCs) have many favorable properties, but the synthesis of solid structures is often hindered by the nanoscale Kirkendall effect. Herein, we present the use of an atomically thin Au3Cu palisade interlayer to reduce lattice mismatch and mediate the Kirkendall effect, enabling the successive topological synthesis of Cu@Au3Cu@Ag, Cu@Au3Cu@Ag2S, and further transformed solid Cu@Au3Cu@CdS core-shell HNCs via cation exchange. The atomically thin and intact Au3Cu palisade interlayer effectively modulates the diffusion kinetics of Cu atoms as demonstrated by experimental and theoretical investigations and simultaneously alleviates the lattice mismatch between Cu and Ag as well as Cu and CdS. The Cu@Au3Cu@CdS HNCs feature exceptional crystallinity and atomically organized heterointerfaces between the plasmonic metal and the semiconductor. This results in the efficient plasmon-induced injection of hot electrons from Cu@Au3Cu into the CdS shell, enabling the Cu@Au3Cu@CdS HNCs to achieve high activity and selectivity for the photocatalytic reduction of CO2 to CO.

One-Step Electrochemical Synthesis of Multiyolk-Shell Nanocoils for Exceptional Photocatalytic Performance.

Multiyolk-shell (mYS) nanostructures have garnered significant interest in various photocatalysis applications such as water splitting and waste treatment. Nonetheless, the complexity and rigorous conditions for the synthesis have hindered their widespread implementation. This study presents a one-step electrochemical strategy for synthesizing multiyolk-shell nanocoils (mYSNC), wherein multiple cores of noble metal nanoparticles, such as Au, are embedded within the hollow coil-shaped FePO4 shell structures, mitigating the challenges posed by conventional methods. By capitalizing on the dissimilar dissolution rates of bimetallic alloy nanocoils in an electrochemically programmed solution, nanocoils of different shapes and materials, including two variations of mYSNCs are successfully fabricated. The resulting Au-FePO4 mYSNCs exhibit exceptional photocatalytic performance for environmental remediation, demonstrating up to 99% degradation of methylene blue molecules within 50 min and 95% degradation of tetracycline within 100 min under ultraviolet-visible (UV-vis) light source. This remarkable performance can be attributed to the abundant electrochemical active sites, internal voids facilitating efficient light harvesting with coil morphology, amplified localized surface plasmon resonance (LSPR) at the plasmonic nanoparticle-semiconductor interface, and effective band engineering. The innovative approach utilizing bimetallic alloys demonstrates precise geometric control and design of intricate multicomponent hybrid composites, showcasing the potential for developing versatile hollow nanomaterials for catalytic applications.

Sphere-Confined Reversible Zn Deposition for Stable Alkaline Aqueous Batteries.

The practical applications of alkaline zinc-based batteries are challenged by poor rechargeability with an insufficient zinc utilization ratio. Herein, a sphere-confined reversible zinc deposition behavior from a free-standing Zn anode is reported, which is composed of bi-continuous ZnO-protected interconnected and hollowed Zn microspheres by the Kirkendall effect. The cross-linked Zn network with in situ formed outer ZnO shell and inner hollow space not only inhibits side reactions but also ensures long-range conductivity and accommodates shape change, which induces preferential reversible zinc dissolution-deposition process in the inner space and maintains structural integrity even under high zinc utilization ratio. As a result, the Zn electrode can be stably cycled for 390 h at a high current density of 20 mA cm-2 (60% depth of discharge), outperforming previously reported alkaline Zn anodes. A stable zinc-nickel oxide hydroxide battery with a high cumulative capacity of 8532 mAh cm-2 at 60% depth of discharge is also demonstrated.

Sodium chloride modulated construction of hollow Co/Co3O4 heterostructure with enhanced mesoscale diffusion towards overall water splitting.

Fabricating an efficient electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) isthe most challenging task for overall water splitting. Herein, we utilized the confinement effect of molten sodium chloride (NaCl) to controllably prepare hollow Co/Co3O4 nanoparticles embedded into nitrogen-doped carbon (H-Co/Co3O4-NC). Experimental and theoretical investigations revealed that the interfacial interaction within Co/Co3O4 heterostructure played a pivotal role in modulating the electronic structure and facilitating the electron transfer. Meanwhile, the superiority of hollow nanostructure could promote the mesoscale mass diffusion. Remarkably, the as-prepared H-Co/Co3O4-NC catalyst achieved the low overpotentials of 316 mV and 252 mV towards OER and HER, respectively, which delivered overall water splitting with the potential of 1.76 V at a current density of 10 mA cm-2.

Ball-in-ball NiS2@CoS2 heterojunction driven by Kirkendall effect for high-performance Mg2+/Li+ hybrid batteries.

Mg2+/Li+ hybrid batteries (MLHBs), which support the rapid insertion and removal of Mg2+/Li+ bimetallic ions, are promising energy storage systems. Inspired by the Kirkendall effect, ball-in-ball bimetallic sulfides with heterostructures were prepared as cathode materials for the MLHBs. First, a nickel-cobalt precursor (NiCo-X precursor) with three-dimensional (3D) nanosheets on its surface was prepared using a solvothermal method based on the association reaction between alkoxide molecules. Subsequently, the NiCo-X precursor was vulcanized at high temperature using the potential energy difference as the driving force to successfully prepare NiS2@CoS2 core-shell hollow spheres. When used as the positive electrode material for the MLHBs, the NiS2@CoS2 hollow spheres exhibited excellent Mg2+/Li+ ion storage capacity, high specific capacity, good rate performance, and stable cyclic stability owing to their tough hierarchical structure. At a current density of 500 mA g-1, a specific capacity of 536 mAh g-1 was maintained after 200 cycles. By explaining the transformation mechanism of Mg2+/Li+ in bimetallic sulfides, it was proven that Mg2+ and Li+ worked cooperatively. This study provides a new approach for developing MLHBs with good electrochemical properties.

Fabrication of ß-Ga2O3 Nanotubes via Sacrificial GaSb-Nanowire Templates.

ß-Ga2O3 nanostructures are attractive wide-band-gap semiconductor materials as they exhibit promising photoelectric properties and potential applications. Despite the extensive efforts on ß-Ga2O3 nanowires, investigations into ß-Ga2O3 nanotubes are rare since the tubular structures are hard to synthesize. In this paper, we report a facile method for fabricating ß-Ga2O3 nanotubes using pre-synthesized GaSb nanowires as sacrificial templates. Through a two-step heating-treatment strategy, the GaSb nanowires are partially oxidized to form ß-Ga2O3 shells, and then, the residual inner parts are removed subsequently in vacuum conditions, yielding delicate hollow ß-Ga2O3 nanotubes. The length, diameter, and thickness of the nanotubes can be customized by using different GaSb nanowires and heating parameters. In situ transmission electron microscopic heating experiments are performed to reveal the transformation dynamics of the ß-Ga2O3 nanotubes, while the Kirkendall effect and the sublimation process are found to be critical. Moreover, photoelectric tests are carried out on the obtained ß-Ga2O3 nanotubes. A photoresponsivity of ~25.9 A/W and a detectivity of ~5.6 × 1011 Jones have been achieved with a single-ß-Ga2O3-nanotube device under an excitation wavelength of 254 nm.

A multiple Kirkendall strategy for converting nanosized zero-valent iron to highly active Fenton-like catalyst for organics degradation.

Nanosized zero-valent iron (nZVI) is a promising persulfate (PS) activator, however, its structurally dense oxide shell seriously inhibited electrons transfer for O-O bond cleavage of PS. Herein, we introduced sulfidation and phosphorus-doped biochar for breaking the pristine oxide shell with formation of FeS and FePO4-containing mixed shell. In this case, the faster diffusion rate of iron atoms compared to shell components triggered multiple Kirkendall effects, causing inward fluxion of vacancies with further coalescing into radial nanocracks. Exemplified by trichloroethylene (TCE) removal, such a unique "lemon-slice-like" nanocrack structure favored fast outward transfer of electrons and ferrous ions across the mixed shell to PS activation for high-efficient generation and utilization of reactive species, as evidenced by effective dechlorination (90.6%) and mineralization (85.4%) of TCE. [Formula: see text] contributed most to TCE decomposition, moreover, the SnZVI@PBC gradually became electron-deficient and thus extracted electrons from TCE with achieving nonradical-based degradation. Compared to nZVI/PS process, the SnZVI@PBC/PS system could significantly reduce catalyst dosage (87.5%) and PS amount (68.8%) to achieve nearly complete TCE degradation, and was anti-interference, stable, and pH-universal. This study advanced mechanistic understandings of multiple Kirkendall effects-triggered nanocrack formation on nZVI with corresponding rational design of Fenton-like catalysts for organics degradation.

Oxygen Plasma Induced Nanochannels for Creating Bimetallic Hollow Nanocrystals.

Platinum-based metal catalysts are considered excellent converters in various catalytic reactions, particularly in fuel cell applications. The atomic structure at the nanocrystal surface and the metal interface both influence the catalytic performance, controlling the efficiency of the electrochemical reactions. Here we report the synthesis of Ag/Pt and Ag/Pd core/shell nanocrystals and insight into the formation mechanism of these bimetallic core/shell nanocrystals when undergoing oxygen plasma treatment. We carefully designed the oxidation treatment that determines the structural and compositional evolution. The accelerated oxidation-triggered diffusion of Ag toward the outer metal shell leads to the Kirkendall effect. After prolonged oxygen plasma treatment, most core/shell nanocrystals evolve into hollow spheres. At the same time, a minor fraction of the metal remains unchanged with a well-protected Ag core and a monocrystalline Pt or Pd shell. We hypothesize that the O2 plasma disturbs the Pt or Pd shell surface and introduces active O species that react with the diffused Ag from the inside out. Based on EDX elemental mapping, combined with several electron microscopic techniques, we deduced the formation mechanism of the hollow structures to be as follows: (I) the oxidation of Ag within the Pt or Pd lattice causes a disrupted crystal lattice of Pt or Pd; (II) nanochannels arise at the defect locations on the Pt or Pd shell; (III) the remaining Ag atoms pass through these nanochannels and leave a hollow crystal behind. Our findings deepen the understanding of interface dynamics of bimetallic nanostructured catalysts under an oxidative environment and unveil an alternative approach for catalyst pretreatment.

Cobalt vacancy-originated TiMnCoCN compounds with a self-adjusting ability for the high-efficiency acidic oxygen evolution reaction.

Oxygen evolution reaction (OER) electrocatalysts in acidic media, except for precious IrO2, have difficulty realizing good electrocatalytic activity and high electrochemical stability simultaneously. However, the scarcity of IrO2 as an acidic OER electrocatalyst impedes its large-scale application in hydrogen generation, organic synthesis, nonferrous metal production and sewage disposal. Herein, we report the design and fabrication of a nanoporous TiMnCoCN compound based on the nanoscale Kirkendall effect, possessing an intriguing self-adjusting capability for the oxygen evolution reaction (OER) in a 0.5 M H2SO4 solution. The nanoporous TiMnCoCN compound electrode for the acidic OER displays a low overpotential of 143 mV for 10 mA cm-2 and exhibits no increase in potential over 50,000 s, which is ascribed to the self-adjusting ability, Carbon/nitrogen (C/N) incorporation and nanoporous architecture. The concentration of inert TiO2 on the reconstructed surface of the compound can self-adjust with the change in OER potential via a cobalt-dissolved vacancy approach according to the stabilization requirement. In this work, the self-reconstruction law of surface structure was discovered, providing a novel strategy for designing and fabricating nonnoble OER electrocatalysts with superior catalytic performance and robust stability in acidic media.

In Situ Electron Microscopy of Transformations of Copper Nanoparticles under Plasmonic Excitation.

Metal nanoparticles are attracting interest for their light-absorption properties, but such materials are known to dynamically evolve under the action of chemical and physical perturbations, resulting in changes in their structure and composition. Using a transmission electron microscope equipped for optical excitation of the specimen, the structural evolution of Cu-based nanoparticles under simultaneous electron beam irradiation and plasmonic excitation was investigated with high spatiotemporal resolution. These nanoparticles initially have a Cu core-Cu2O oxide shell structure, but over the course of imaging, they undergo hollowing via the nanoscale Kirkendall effect. We captured the nucleation of a void within the core, which then rapidly grows along specific crystallographic directions until the core is hollowed out. Hollowing is triggered by electron-beam irradiation; plasmonic excitation enhances the kinetics of the transformation likely by the effect of photothermal heating.

Advanced In Situ Electrochemical Induced Dual-Mechanism Heterointerface toward High-Energy Aqueous Zinc-Ion Batteries.

In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, while the mechanism behind is still needed to study deeply. Herein, an in situ electrochemically approach is developed for the activation of heterointerface MnOx /Co3 O4 by inducing Mn-defect, wherein the Mn defects are formed through a charge process that converts the MnOx with poor electrochemical activities toward Zn2+ into high electrochemically active cathode for aqueous zinc-ion batteries (ZIBs). Guided by the coupling engineering strategy, the heterointerface cathode exhibits an intercalation/conversion dual-mechanism without structural collapse during storage/release of Zn2+ . The heterointerfaces between different phases can generate built-in electric fields, reducing the energy barrier for ion migration and facilitating electron/ion diffusion. As a consequence, the dual-mechanism MnOx /Co3 O4 shows an outstanding fast charging performance and maintains a capacity of 401.03 mAh g-1 at 0.1 A g-1 . More importantly, a ZIB based on MnOx /Co3 O4 delivered an energy density of 166.09 Wh kg-1 at an ultrahigh power density of 694.64 W kg-1 , which outperforms those of fast charging supercapacitors. This work provides insights for using defect chemistry to introduce novel properties in active materials for highly for high-performance aqueous ZIBs.

Facile synthesis of ZnO/ZnS hollow nanorods via Kirkendall effect with enhanced photocatalytic degradation of methylene blue.

Because of the growing concerns about environmental issues, the search of proficient semiconductor catalysts for pollutants degradation from contaminated water is one of the interesting areas of research. Due to the larger surface area, hollow nanomaterials with hollow interior and outer thickness illustrate a class of significant nanostructured materials. The enhanced surface area provides remarkable applications of the hollow nanomaterials in catalysis. In Kirkendall effect, pores are formed owing to the diverse diffusion rates of two nanomaterials in a diffusion couple. Here, we have introduced the facile hydrothermal synthesis of hollow nanorods of ZnO/ZnS via Kirkendall effect using ZnO nanorods (NRs). The morphologies, optical properties, compositions, and crystal structures of the as synthesized materials are systematically studied using UV-vis, PXRD, FESEM, TEM, EDS, XPS, etc. The process of synthesis and growth mechanism of hollow NRs is suggested based on the Kirkendall effect. A hollow nanomaterial, envisaged being highly efficient for molecule adsorption on its surface, the as synthesized materials were used for the photocatalytic degradation of methylene blue (MB) dye. MB degradation efficiency of 96% within 60 min was performed over ZnO/ZnS hollow NRs, which was 2.6-fold greater than that of ZnO. The rate constant of ZnO/ZnS heterostructure was 0.045 min-1, which was 5.5 times larger than that of bare ZnO. We have concluded our work in the directions towards the synthesis of various semiconductor hollow nanostructures for the varied catalytic reactions.

Morphology Engineering in Multicomponent Hollow Metal Chalcogenide Nanoparticles.

Hollow metal chalcogenide nanoparticles are widely applicable in environmental and energy-related processes. Herein, we synthesized such particles with large compositional and morphological diversity by combining scanning probe block copolymer lithography with a Kirkendall effect-based sulfidation process. We explored the influence of temperature-dependent diffusion kinetics, elemental composition and miscibility, and phase boundaries on the resulting particle morphologies. Specifically, CoNi alloys form single-shell sulfides for the synthetic conditions explored because Co and Ni exhibit similar diffusion rates, while CuNi alloys form sulfides with various types of morphologies (yolk-shell, double-shell, and single-shell) because Cu and Ni have different diffusion rates. In contrast, Co-Cu heterodimers form hollow heterostructured sulfides with varying void numbers and locations depending on synthesis temperature and phase boundary. At higher temperatures, the increased miscibility of CoS2 and CuS makes it energetically favorable for the heterostructure to adopt a single alloy shell morphology, which is rationalized using density functional theory-based calculations.

Synthesis of L10 -Iron Triad (Fe, Co, Ni)/Pt Intermetallic Electrocatalysts via a Phosphide-Induced Structural Phase Transition.

Structurally ordered L10 -iron triad (Fe, Co, Ni)/Pt with a M(iron triad)/Pt ratio ≈1:1 has drawn increasing attention in oxygen reduction reaction (ORR) electrocatalysis and fuel cell technologies by virtue of the high performance derived from their strong surface strain. However, the synthesis of intermetallic L10 -M(iron triad)Pt generally requires the accurate content control of the multicomponent and the sufficient thermal energy to overcome the kinetic barrier for atom diffusion. This work reports a synthesis of sub ≈5 nm L10 -intermetallic nanoparticles using phosphide intermediate-induced structural phase transition. Taking the L10 -CoPt intermetallic, for example, the formation of the L10 structure depends on the Co2 P intermediates can provide abundant P vacancies to accelerate the Pt diffusion into the orthorhombic Co-rich skeletons, instead of the traditional route of intermetallic from solid solution. L10 -CoPt prepared by this method has a high degree of ordering and shows the broad adaptability of various Pt-based electrocatalysts with different loading and states to improve their electrocatalytic performance. Additionally, the other L10 -M(iron triad)Pt intermetallics, i.e., L10 -NiPt and L10 -FePt, are also prepared through this phosphide-induced phase transition. The findings provide a promising strategy for designing other intermetallic materials alloy materials using a structural phase transition induced by a second phase.

One-Step Synthesis of Multi-Core-Void@Shell Structured Silicon Anode for High-Performance Lithium-Ion Batteries.

The core-void@shell architecture shows great advantages in enhancing cycling stability and high-rate performance of Si-based anodes. However, it is usually synthesized by template methods which are complex and environmentally unfriendly and would lead to low-efficiency charge and mass exchange because of the single-point van der Waals contact between the Si core and the shell. Here, a facile and benign one-step method to synthesize multi-Si-void@SiO2 structure, where abundant void spaces exist between multiple Si cores that are multi-point attached to a SiO2 shell through strong chemical bonding, is reported. The corresponding electrode exhibits highly stable cycling stability and excellent electrochemical performance. After 200 cycles at a current density of 0.1 A g-1 and then another 200 cycles at 1.2 A g-1 , the electrode outputs a specific capacity of 1440 mAh g-1 . Even at 2.0 A g-1 , it outputs a specific capacity as high as 1182 mAh g-1 . Such an anode can match almost all the cathode materials presently used in lithium-ion batteries. These results demonstrate the multi-Si-void@SiO2 as a promising anode to be used in future commercial lithium-ion batteries of high energy density and high power density.

An Effective Photocatalytic Degradation of Industrial Pollutants through Converting Titanium Oxide to Magnetic Nanotubes and Hollow Nanorods by Kirkendall Effect.

Controlling of morphology from nanoparticles to magnetic nanotubes and hollow nanorods are interesting for developing the photo-active materials and their applications in the field of photocatalysis and decontamination of aquatic effluents. In the current study, titanium dioxide nanoparticles and nanocomposites were prepared by different techniques to produce various morphologies. The nanoparticles of pure titanium dioxide were prepared by sol-gel technique. Magnetic nanotubes and hollow nanorods were prepared by combining titanium with di- and tri-valent iron through two stages: urea hydrolysis and solvent thermal technique. According to the Kirkendall effect, magnetic nanotubes were fabricated by unequal diffusion of Fe2+, Fe3+ and Ti4+ inside the nanocomposite to produce maghemite-titanian phase. In the same trend, hollow nanorods were synthesized by limited diffusion of both trivalent iron and tetravalent titanium producing amorphous structure of titanium iron oxides. The magnetic and optical properties showed that these nanotubes and hollow nanorods are magnetically active and optically more effective compared with titanium dioxide nanoparticles. Therefore, the Naphthol green B dye completely disappeared after 45 min of UV light irradiation in presence of the hollow nanorods. The kinetic study confirmed the high performance of the hollow nanorods for the photocatalytic degradation of Naphthol green B compared with titanium dioxide nanoparticles.

Environmental STEM Study of the Oxidation Mechanism for Iron and Iron Carbide Nanoparticles.

The oxidation of solution-synthesized iron (Fe) and iron carbide (Fe2C) nanoparticles was studied in an environmental scanning transmission electron microscope (ESTEM) at elevated temperatures under oxygen gas. The nanoparticles studied had a native oxide shell present, that formed after synthesis, an ~3 nm iron oxide (FexOy) shell for the Fe nanoparticles and ~2 nm for the Fe2C nanoparticles, with small void areas seen in several places between the core and shell for the Fe and an ~0.8 nm space between the core and shell for the Fe2C. The iron nanoparticles oxidized asymmetrically, with voids on the borders between the Fe core and FexOy shell increasing in size until the void coalesced, and finally the Fe core disappeared. In comparison, the oxidation of the Fe2C progressed symmetrically, with the core shrinking in the center and the outer oxide shell growing until the iron carbide had fully disappeared. Small bridges of iron oxide formed during oxidation, indicating that the Fe transitioned to the oxide shell surface across the channels, while leaving the carbon behind in the hollow core. The carbon in the carbide is hypothesized to suppress the formation of larger crystallites of iron oxide during oxidation, and alter the diffusion rates of the Fe and O during the reaction, which explains the lower sensitivity to oxidation of the Fe2C nanoparticles.

Electrocatalyst based on Ni2P nanoparticles and NiCoP nanosheets for efficient hydrogen evolution from urea wastewater.

Urea electrolysis is a promising approach to produce hydrogen while simultaneously purifying urea-rich wastewater. In practice, it is highly desirable but still challenging, through the structure construction strategy, to implement a method with controllable synthesis of ultra-thin nanosheet arrays with rich interfaces, and then apply them into the catalysis operations of hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). In this work, the bifunctional electrocatalyst Ni2P/NiCoP nanosheets anchored nickel foam (NF) were prepared with ultra-thin rich interfaces by regulating the Co- and P-doping. The results showed that the elaborated Ni2P/NiCoP/NF electrode delivered the excellent electrocatalytic activities for both UOR and HER operations. Particularly for UOR, it required only a cell voltage of 1.41 V at 100 mA cm-2, which was 400 mV lower than that in the traditional overall water splitting operation.

Architectural Genesis of Metal(loid)s with Iron Nanoparticle in Water.

Reactions of core-shell iron nanoparticles with metal(loid)s in water can form an array of nanostructures such as Ag-seed/dendrite, As-subshell, U-yolk, Co-hollowshell, and Cs-spot. Nonetheless, there is a lack of profound understanding in the genesis of these amazing geometries. Herein, we propose a concept to unravel the interdiffusion between the core-shell iron nanoparticle and metal(loid)s, where several key interactions including the Kirkendall effect, metal(loid) character effect, and reaction condition effect are involved in determining the structure of the final solid reaction products. Particularly, the architectural growths of metal(loid)s with iron nanoparticles in water can be manipulated mutually or singly by the following factors: standard redox potential difference, magnetic property, electrical charge and conductivity, as well as the iron (hydr)oxide shell structure under different solution chemistry and operation conditions. This contribution provides a theoretical basis to rationalize the architectural genesis of various metal(loid)s with iron nanoparticles, which will benefit the real practice for synthesizing functional iron-based nanoparticles and recovering the rare/precious metal(loid)s by iron nanoparticles from water.