Electron-rich Regions Research Articles

Measurement of electron energetics in the equatorial and polar planes of a compact dipole plasma driven at steady state

The electron energy distribution function (EEDF) is investigated in a plasma driven at steady state and confined by a single permanent dipole magnet, employing electron cyclotron resonance heating using microwaves of 2.45 GHz. Directional retarding field energy analyzers are used to explore the EEDF in the equatorial and polar planes of the dipole magnetic field. The plasma confined in the magnetic field is found to be Maxwellian in most of the available space. Electrons have higher values of average energy () in the direction parallel to the magnetic field for both the equatorial and polar planes. The energetic electron rich regions are found at specific locations (r = 9 cm in the equatorial plane, and r = 5 cm and near the boundary region around r = 17 cm in the polar plane). The process rates such as electron neutral collisions and ionization show anisotropic variation in the polar plane of the dipole plasma.

Active sites engineering on FeNi alloy/Cr3C2 heterostructure for superior oxygen evolution activity

Exploring high active electrocatalysts for oxygen evolution reaction (OER) is of great significance for a sustainable hydrogen economy. The development of non-precious transition metals, with sufficient active sites and ample intrinsic activity, remains a challenge. Herein, a new type of FeNi–Cr3C2 heterostructure anchored on carbon sheets (FeNi–Cr3C2@C) was reported, which can effectively catalyze OER with swift kinetics and outstanding intrinsic activity. The introduced Cr3C2 phase not only serves as a support material but also effectively suppresses the thermal coarsening of FeNi alloy nanoparticle. The FeNi–Cr3C2@C displays a robust OER activity with a low overpotential of 283 mV at the current density of 10 mA cm−2, a high turnover frequency value of 1.69 s−1 at the overpotential of 300 mV (10 times higher than that of FeNi@C) and good stability in alkaline media. Density functional theory calculations (DFT) calculations show that Cr3C2 can facilitate the generation of electron-rich region at the Ni site in FeNi alloys as an active site, exhibiting an optimized adsorption behavior toward oxygen intermediate species with regard to decreased thermodynamic energy barriers. Our work opens up a promising path to modulate the electrocatalytic active sites using inexpensive and durable Cr3C2 for electrochemical catalytic reactions.

Realization of a highly-performing triboelectric nanogenerator utilizing molecular self-assembly

Triboelectric nanogenerator (TENG) is promising as a sustainable power source for energy-autonomous electronics. This work demonstrates for the first time that a highly-performing TENG can be realized by utilizing molecular self-assembly of small molecules. It is found that molecular self-assembly modifies the orbital energy levels of the corresponding tribo-layer that causes reduced energy gap between the tribo-layers for charge transfer. It is also found that an expansion of the electron-rich regions occurs due to molecular self-assembly that in turn increases the probability of the electron cloud/potential well overlap. Both the phenomena result in significantly-enhanced charge transfer between the tribo-positive and tribo-negative layers of a TENG during contact electrification. A low-cost, simple, and straightforward technique that does not require sophisticated equipment is adopted for the molecular self-assembly of a naturally abundant small molecule. Spectroscopic analysis, atomic force microscopy, and electron microscopy reveal that the modified molecules are capable of building high order self-assembled structure. A TENG with a self-assembled layer (SAL-TENG) generated voltage and power density of ∼1340 V and ∼11.75 W m−2, respectively, as compared with, ∼200 V and ∼3.5 W m−2 respectively, for another TENG comprising the same molecules but are not self-assembled (NSA-TENG).

Hydrogen bond recombination regulated by strongly electronegative functional groups in demulsifiers for efficient separation of oil–water emulsions

Tight oil extraction and offshore oil spills generate large amounts of oil–water emulsions, causing serious soil and marine pollution. In such oil–water emulsions, the resin molecules are bound by π–π stacking and bind to interfacial water molecules via hydrogen bonds, which impede the aggregation between water droplets and thereby the separation of the emulsion. In this study, strongly electronegative oxygen atoms (in ethylene oxide, propylene oxide, esters, and hydroxyl groups) were introduced through poly(propylene glycol)-block-polyether and esterification with acrylic acid to attract negative charges in order to form electron-rich regions and enhance interfacial hydrogen bond recombination. The potential distribution in the demulsifier molecules and their space occupancy were regulated by the polymerization reaction to destroy the π–π stacking interaction between resin molecules. The results show that the binding energies (binding free energy and hydrogen bonding energy) of oxygen-containing demulsifier molecules with water molecules were higher than those of resin molecules with water molecules, resulting in the fission of the hydrogen bonds between resin and water molecules. The introduction of demulsifier molecules that occupied large interfacial space reduced the binding energy between resin molecules from −2176.06 to −110.00 kJ·mol−1. Noteworthy, the binding energy between demulsifier molecules and resin molecules was −1076.36 kJ·mol−1 lower than that between resin molecules (−110.00 kJ·mol−1), indicating the adsorption of the surrounding interfacial resin molecules by the demulsifier molecules and destruction of the π–π stacking between them, thus favoring the collapse of the interfacial structure of the oil–water emulsion and achieving its separation. This study provides important theoretical support for the treatment of oil-contaminated soil and offshore oil spill pollution.

Adsorption of hazardous gases on Cyclo[18]carbon and its analogues

Density functional theory calculations were performed to study the adsorption behavior of hazardous gases (NH3, CO2, CO, and NO) on twelve adsorbents (cyclo[18]carbon (C18) and its analogues Al9N9, B9N9, C6B6N6, C12B3N3, C14B2N2, d-C14B2N2, C16BN, C17Si; cyclo[12]carbon (C12) and its analogues Al6N6 and B6N6). The molecular electrostatic potential (MESP) maps of C18 revealed its polyynic structure with alternating electron-rich and electron-deficient regions. The most negative-valued MESP point (Vmin) indicates that the replacement of carbon atoms of C18/C12 by BN/AlN/Si units increases the electron-rich environment in the molecules. In general, NH3 and CO2 are found to be physisorbed on C18/C12 and its analogues. An important result is that the Vmin of C18/C12 and its analogues is linearly correlated with the NH3 and CO2 adsorption energies. The quantum theory of atoms in molecules (QTAIM) results indicate that the interactions of NH3 and CO2 with C18/C12 and its analogues are non-covalent in nature. In general, CO and NO are found to be chemisorbed on C18/C12 and its analogues. In contrast to the cases of NH3 and CO2 adsorption, the Vmin of C18/C12 and its analogues is generally inversely related to the CO and NO adsorption energies. The QTAIM results indicate the strong covalent character of the bonding for CO/C18, CO/C6B6N6, CO/d-C14B2N2, CO/C12, NO/C18, NO/C17Si, and NO/C12 systems. The adsorption process significantly influenced the chemical potential and/or hardness, especially for CO– and NO-adsorbed C18/C12 and its analogues.

DFT Study on Na-Ion Conducting Solid Biopolymer Electrolyte-Based on Agar-Agar and NaPF6 for Sodium-Ion Batteries

This research article is focused on the structural, electronic, thermal, and vibrational properties of solid biopolymer electrolytes based on Agar-Agar and sodium hexafluorophosphate (NaPF6) salt. Herein, the density functional theory (DFT) technique is used to investigate these properties. The structural analysis provides information about the interactions between Agar-Agar and NaPF6 and hence interaction energy is analysed. Thermodynamic parameters such as Gibbs’ free energy (G), enthalpy (H), entropy (S), and specific heat (Cv) etc. are studied by frequency analysis at normal temperature pressure (NTP) of titled electrolytes. The chemical descriptors of the electrolytes have been studied using the molecular orbital theory (MOT). Molecular electrostatic potential surface (MEPS) demonstrates the three-dimensional molecular charge distribution and illustrates the electron-rich and deficit regions over the whole electrolyte system. Mulliken population analysis (MPA) gives the identification of intramolecular hydrogen bonding. The theoretical infrared (IR) study confirms the formation of the complex system between Agar-Agar and NaPF6 salt. The overall DFT studies of sodium ion-based biopolymer electrolytes have better possibilities for safe sodium-ion batteries.

DFT Calculation and MD Simulation Studies on Gemini Surfactant Corrosion Inhibitor in Acetic Acid Media.

Gemini surfactant corrosion inhibitor (CI) is one type of CI mainly used in mitigating corrosion in the complex system of oil/gas production industries. Computer modeling methods such as density functional theory (DFT) calculation and molecular dynamic (MD) simulation are required to develop new CI molecules focusing on their application condition as a prediction or screening process before the physical empirical assessment. In this work, the adsorption inhibition efficiencies of two monomer surfactants (2B and H) and their respective Gemini structures with the addition of different spacers (alkyl, benzene, ester, ether, and ketone) are investigated using DFT calculation and MD simulation method in 3% sodium chloride (NaCl), and 1500 ppm acetic acid solutions. In DFT calculation, 2B-benzene molecules are assumed to have the most promising inhibition efficiency based on their high reactivity and electron-donating ability at their electron-rich benzene ring region based on the lowest bandgap energy (0.765 eV) and highest HOMO energy value (-2.879 eV), respectively. DFT calculation results correlate with the adsorption energy calculated from MD simulation, where 2B-benzene is also assumed to work better as a CI molecule with the most adsorption strength towards Fe (110) metal with the highest negative adsorption energy value (-1837.33 kJ/mol at temperature 323 K). Further, diffusion coefficient and molecular aggregation analysis in different CI concentrations through MD simulation reveals that only a small amount of Gemini surfactant CI is needed in the inhibition application compared to its respective monomer. Computer simulation methods successfully predict and screen the Gemini surfactant CI molecules that can work better as a corrosion inhibitor in acetic acid media. The amount of Gemini surfactant CI that needs to be used is also predicted. The future planning or way forward from this study will be the development of the most promising Gemini surfactant CI based on the results from DFT calculation and MD simulations.

Studying the Biological Activity of Trans-[Cu (quin)2(EtOH)2] as Potent Antimicrobial Cu(II) Complex through Computational Investigations: DFT, ADMET and Molecular Docking.

Trans-[Cu (quin)2(EtOH)2], a new copper (II) complex, was characterized using a variety of computational techniques to explore its biological role in pharmacological applications. The computational methods included density functional theory (DFT), ADMET and molecular docking. The optimized geometrical parameters revealed that the plane containing the Cu ion and the Quinaldinate ligands was confirmed to be nearly planar. DFT findings suggest that the complex has a stable structure with a moderate band gap of 3.88 eV. Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) analysis revealed a planar surface intramolecular charge transfer from its donor sites, in the center, to its ends instead of the vertical plane. Two electron-rich regions were observed around the oxygen ions in the molecular electrostatic potential (MEP) map, which were expected to be the sites of molecular bonding and interactions with target proteins. Drug-likeness and pharmacokinetics parameters were determined to provide insight into the safety level of the studied compound. The ADMET (absorption, distribution, metabolism, excretion, and toxicity) results showed favorable pharmacological features, as evidenced by a high oral bioavailability and a low risk of toxicity. A molecular docking study was performed by fitting the copper complex into the active sites of target proteins for Bacillus cereus, Staphylococcus aureus, and Escherichia coli bacteria. The title complex had the strongest antifungal effect within the inhibitory zone of B. cereus with a strong binding affinity of -9.83 kcal/mol. Also, maximum activity was exhibited against S.aureus (-6.65 kcal/mol) compared to the other recently reported Cu complexes within the limits of the screened references. Docking studies implicated modest inhibitory activity against E. coli bacteria. The findings highlighted the compound's biological activities and identified it as a possible treatment drug for the bacteria B. cereus and S. aureus.

NiCo Nanolayered Double Hydroxides on Fe/Ni Metal–Organic Frameworks for Oxygen Evolution

Modulation of oxygen intermediates in the oxygen evolution reaction (OER) tends to be an effective method for intensifying OER activity. In this paper, NiCo nanolayered double hydroxide (NC-LDH)-decorated FeNi bimetallic metal–organic framework (FN-MIL) heterostructures were constructed for enhanced OER performance. Various characteristics including Raman and Fourier-transform infrared spectra, X-ray diffraction patterns, scanning and transmission electron microscopy images, and X-ray photoelectron spectroscopy spectra help to explore the composition and microstructure. The band gap of samples was discussed using Mott–Schottky curves and Tauc plots to analyze the interfacial electron transfer driven by the energy level difference, resulting in the formation of electron-rich and electron-deficient regions at the interface and realizing the directed modulation of oxygen intermediates. The as-prepared composite catalyst revealed excellent OER performance, long-term stability, a high faradic efficiency of 97.8%, and a low potential of 244 mV at 10 mA cm–2 (without iR-compensation). Interestingly, the catalyst maintained high OER activity in seawater containing 1 M KOH due to its favorable resistance to chloride ions, suggesting an appealing prospect in practical application.

Construction of carbon nitride-based heterojunction as photocatalyst for peroxymonosulfate activation: Important role of carbon dots in enhancing photocatalytic activity

Strategic combination of carbon dots (CDs) and carbon nitride (CN) has provided an appealing strategy to synthesize metal-free carbonaceous catalyst for environmental-concerned photocatalytic applications. However, there still exists an ambiguous cognition on the relationship between functional structures of CDs and enhanced photocatalytic activity of CDs/CN composites. Herein, different types of functionalized CDs were physically integrated with CN matrix to construct CDs/CN heterojunctions. By systematically investigating the efficiency of CDs/CN-catalyzed peroxymonosulfate (PMS) in p-nitrophenol degradation, we revealed that the CDs enriched with carboxyl groups or doped by pyrrolic-N inclined to attract photogenerated electrons from CN host, and thus contributed to the photocarriers separation. As such, these CDs-imparted active sites can dramatically facilitate PMS activation, and further p-nitrophenol degradation by photogenerated holes and multiple reactive oxygen radicals. Nonetheless, the CDs mainly doped by electron-donating graphitic-N could form electron-rich regions at the interface of CN host upon forming heterojunction, thus making barriers against charge separation in the PMS-mediated oxidation process. Taken together, this study will shed light on the rational design of CDs/CN heterojunctions with high photocatalytic activity.

Surface and interface mediated magnetism in mesoscopic ceria@carbon core–shell structures

CeO2@C submicron core–shell structure was prepared by a two-step synthesis method, and the ceria shell thickness and its microstructure were precisely controlled by the precursor composition and annealing process. The results show that forming the thin ceria shell by aggregating nanoparticles on the surface of the carbon sphere is more favorable for forming ferromagnetism than merely dispersed ceria nanoparticles. The saturation magnetization increases with decreasing shell thickness, indicating the contributions of surfaces and interfaces to the magnetism. Furthermore, high-temperature reduction results in shell densification and the aggregation of defects at the surface. The spectroscopic and microscopic measurements reveal that in such cases, a continuous defect-rich area with a sub-nanometric thickness, doped with electrons extends over the whole surface of the mesostructure. The magnetic strength difference caused by adjusting the thickness of this defective layer from several nanometers to sub-nanometric width can reach 360 times, suggesting that the magnetization of these mesoscopic systems is related to the presence of these quasi-2D electron-rich regions on the surface. This study shows the applicability of giant orbital magnetism to mesoscopic systems, and the results can also provide a reference for the subsequent synthesis of magnetic materials.

A WO3–TiO2 nanorod/CaCO3 photocatalyst with degradation-regeneration double sites for NO2-inhibited and durable photocatalytic NO

As a promising cleaner technology for nitric oxide degradation, photocatalysis has attracted extensive attention, while the main limitations of photocatalytic nitric oxide are that the toxic NO2 is produced easily and the photocatalytic durability was inferior due to the accumulation of photocatalytic products. In this paper, a WO3–TiO2 nanorod/CaCO3 (TCC) insulating heterojunction photocatalyst with degradation-regeneration double sites was prepared by simple grinding and calcining. The effects of CaCO3 loading on the morphology, microstructure and composition of TCC photocatalyst were investigated by SEM, TEM, XRD, FT-IR and XPS etc. Also, TCC exhibits NO2-inhibited and durable characteristics for NO degradation. DFT calculation, the detection of active radicals by EPR, capture test and the NO degradation pathway characterized by in-situ FT-IR spectra showed that the electron-rich region formed and the existence of regeneration sites are the main reasons for promoting the NO2-inhibited and durable NO degradation. Furthermore, the mechanism of NO2-inhibited and durable NO degradation by TCC was revealed. Finally, TCC superamphiphobic photocatalytic coating was prepared, which still exhibits similar NO2-inhibited and durable characteristics for NO degradation to TCC photocatalyst. It may provide new application value and development prospects in the field of photocatalytic NO.

Defect-rich ruthenium dioxide electrocatalyst enabled by electronic reservoir effect of carbonized polymer dot for remarkable pH-universal oxygen evolution

Designing highly active and durable electrocatalysts for oxygen evolution reaction (OER) over a wide pH range is of great significance, but it remains challenging. Herein, a defect-rich RuO2 electrocatalyst with pH-universal OER activity is developed by rationally utilizing the electronic reservoir effect of Mn-coordinated carbonized polymer dots (Mn-CPDs). Mn-CPDs as distinct electron acceptor/donor endows Ru-O sites of RuO2 with abundant defective structures (i.e., O-Ru-O-Ru-Ru sites and O-Ru-O-Mn units) via reduction-oxidation processes, with incorporated Mn atoms simultaneously feeding electron to Ru. The resultant Ru-O-Mn/CPD exhibits an ultralow OER potential of 196 mV, 194 mV and 251 mV at 10 mA·cm−2 under 0.5 M H2SO4, 1.0 M KOH, and 1.0 M PBS media, respectively, and long-term catalytic stability, which are among the best OER electrocatalysts. Surprisingly, Ru-O-Mn/CPD also shows great Pt-like hydrogen evolution activity. The theoretical simulation indicates that defective Ru-O-Mn structures produce electron-rich Ru region and near-optimal Ru-4d/O-2p band center, thus optimizing the adsorption/desorption kinetics of key intermediates.

Insight into Diphenyl Phosphine Oxygen-Based Molecular Additives as Defect Passivators toward Efficient Quasi-2D Perovskite Light-Emitting Diodes.

The introduction of additives has become an important method for enhancing the device performance of quasi-two-dimensional perovskite light-emitting diodes. In this work, we systematically studied the electronic and spatial effects of molecular additives on defect passivation abilities using the methyl, hydrogen, and hydroxyl groups substituted three diphenyl phosphine oxygen additives. The electron-donating conjugation effect of the hydroxyl group on diphenylphosphinic acid (OH-DPPO) leads to a more electron-rich region in OH-DPPO, and the hydroxyl group has a moderate steric hindrance. All these factors endow it with best passivation ability than the other two additives. Furthermore, ion migration was suppressed due to hydrogen bonding between the hydroxyl group and Br. Ultimately, the OH-DPPO passivated devices achieved an external quantum efficiency of 22.44% and a 6-fold improvement in lifetime. These findings provide guidance for developing multifunctional additives in the field of perovskite optoelectronics.

Regulating the Fe-spin state by Fe/Fe3C neighbored single Fe-N4 sites in defective carbon promotes the oxygen reduction activity

Non-noble iron-based single-atom catalysts (Fe-N-C) require more accessible active sites and rapid mass transportation, and spin state regulation of iron atoms is also key but challenging to synergistically improve the zinc-air battery (ZAB) performance. Thus, here we indicate that by pre-preparing a 3D nitrogen-doping carbon-sheet network from in situ gas-molecule cutting of bulk MOF and then adsorbing iron into defects and pores of this preformed matrix, we achieve a Fe-N-C catalyst with 14.78 wt.% iron existed as single-atom Fe-N4 sites neighboured Fe/Fe3C nanostructures. Electrons transfer to Fe3C/FeN4 from the adsorbed Fe atom and forms an electron-rich region around Fe3C, achieving the spin-state modulation of the d-band center of Fe atom in FeN4 through charges transfer. The calculation proves that d-band centers of spin-up/down for Fe in Fe-Fe3C/FeN4 are closer to the Fermi level than that of Fe3C/FeN4 (-1.51/-0.72 eV vs. -1.47/-0.65 eV), implying Fe site in Fe-Fe3C/FeN4 is more chemically active and is beneficial to the adsorption and reaction of O2 when involved in ORR. This catalyst delivers excellent ORR activity and the primary ZAB performance with the energy density (ED) of up to 1002 mWh g-1 Zn at 50 mA cm−2 and the maximum power density of 212 mW cm−2, especially in which it displays an excellent durability with 92.7% ED retention during a ∼150 h continuous discharge. These results highlight the significance of metal-atoms spin-state modulation by coupled active metal-species in hybrid catalysts for electrochemical energy devices.

Se⋯π Chalcogen Bonding in 1,2,4-Selenodiazolium Tetraphenylborate Complexes

The series of substituted 1,2,4-selenodiazolium tetraphenylborate complexes were synthesized via cyclization between 2-pyridylselenylchloride, followed by the anion metathesis, and fully characterized. The utilization of tetraphenylborate anion, a strong π-electron donor via its phenyl rings, promoted the formation of assemblies exhibiting selenium–π interactions. The chalcogen bonding (ChB) interactions involving the π-systems of the tetraphenylborate anion were studied using density functional theory (DFT) calculations, where “mutated” anions were used to estimate the strength of the Se···π chalcogen bonds. Moreover, molecular electrostatic potential (MEP) surfaces were used to investigate the electron-rich and poor regions of the ion pairs. The quantum theory of atoms-in-molecules (QTAIM) and the noncovalent interaction (NCI) plot methods based on the topology of the electron density were used and combined to characterize the ChBs. The investigation reported herein disclosed that the formation of symmetrical dimers can be broken by the introduction of a stronger π-acceptor and, consequently, forming stronger Se···π contacts with selenodiazolium cations.

Investigation of Methyl-5-(pentan-3-yloxy)-7-oxabicyclo[4.1.0]hept-3-ene-3-carboxyhydrazide Derivatives as Potential Inhibitors of COVID-19 Main Protease: DFT and Molecular Docking Study.

The search for effective therapeutics to combat COVID-19 has led to the exploration of the biological activity of numerous compounds. In this study, hydrazones derived from oseltamivir intermediate, methyl 5-(pentan-3-yloxy)-7-oxabicyclo[4.1.0]hept-3-ene-3-carboxylate have been investigated for their potential as drug candidates against the COVID-19 virus using computational methods, including density functional theory (DFT) studies, molecular docking, and absorption, distribution, metabolism, excretion and toxicity (ADMET) analysis. The DFT studies provide information on the electronic properties of the compounds while the molecular docking results using AutoDock reported the binding energies between the main protease of COVID-19 and the compounds. The DFT results revealed that the energy gap of the compounds ranged from 4.32 to 5.82 eV while compound HC had the highest energy gap (5.82 eV) and chemical potential (2.90 eV). The electrophilicity index values of the 11 compounds ranged from 2.49 to 3.86, thus they were classified as strong electrophiles. The molecular electrostatic potential (MESP) revealed electron-rich and electron-deficient regions of the compounds. The docking results reveal that all the compounds had better docking scores than remdesivir and chloroquine, frontline drugs employed in combating COVID-19, with HC having the best docking score of -6.5. The results were visualized using Discovery studio, which revealed hydrogen bonding, pi-alkyl interaction, alkyl interaction, salt bridge interaction, halogen interaction as being responsible for the docking scores. The drug-likeness results showed that the compounds qualify as oral drug candidates as none of them violated Vebers and Lipinski's rule. Thus, they could serve as potential inhibitors of COVID-19.

Bimetallic oxide Cu2O@MnO2 with exposed phase interfaces for dual-effect purification of indoor formaldehyde and pathogenic bacteria.

The combination of materials with different functions is an optimal strategy for synchronously removing various indoor pollutants. For multiphase composites, exposing all components and their phase interfaces fully to the reaction atmosphere is a critical problem that needs to be solved urgently. Here, a bimetallic oxide Cu2O@MnO2 with exposed phase interfaces was prepared by a surfactant-assisted two-step electrochemical method, which shows a composite structure of non-continuously dispersed Cu2O particles anchored on flower-like MnO2. Compared with the pure catalyst MnO2 and bacteriostatic agent Cu2O, Cu2O@MnO2 respectively shows superior dynamic formaldehyde (HCHO) removal efficiency (97.2% with a weight hourly space velocity of 120 000 mL g-1 h-1) and pathogen inactivation ability (the minimum inhibitory concentration for 104 CFU mL-1 Staphylococcus aureus is 10 μg mL-1). According to material characterization and theoretical calculation, its excellent catalytic-oxidative activity is attributable to the electron-rich region at the phase interface which is fully exposed to the reaction atmosphere, inducing the capture and activation of O2 on the material surface, and then promoting the generation of reactive oxygen species that can be used for the oxidative-removal of HCHO and bacteria. Additionally, as a photocatalytic semiconductor, Cu2O further enhances the catalytic ability of Cu2O@MnO2 under the assistance of visible light. This work will provide efficient theoretical guidance and a practical basis for the ingenious construction of multiphase coexisting composites in the field of multi-functional indoor pollutant purification strategies.

Creating an electron-rich region on ultrafine Bi2O3 nanoparticles to boost the electrochemical carbon dioxide reduction to formate

Metal–support interfacial interactions can enrich the electron density of Bi2O3 effectively facilitating *COO intermediate generation and boosting catalytic activity.

Reductive dehalogenation in groundwater by Si-Fe(II) co-precipitates enhanced by internal electric field and low vacancy concentrations

Fe(II) and silicate can form Si-Fe(II) co-precipitates in anoxic groundwater and sediments, but their phase composition and reactivity towards subsurface pollutants are largely unknown. Three types of Si-Fe(II) co-precipitations with the same chemical composition, namely Si-Fe(II)-I, Si-Fe(II)-II, and Si-Fe(II)-III, have been synthesized by different hydroxylation sequences in this work. It was found that Si-Fe(II)-III reduce carbon tetrachloride (CT) much faster (k1=0.04419 min−1) than Si-Fe(II)-I (0 min−1) and Si-Fe(II)-II (7.860 × 10−4 min−1). XRD results show that the main component of Si-Fe(II)-III is ferrous silicate (FeSiO3), which is quite different from that of Si-Fe(II)-I and Si-Fe(II)-II. The unique arrangement of hydroxyl coordination, the less distorted octahedral structure, the polyhedral morphology and the absence of Si-A center vacancies in Si-Fe(II)-III are responsible for its high reductive dehalogenation reactivity. The highest redox activity of Si-Fe(II)-III was shown by electrochemical characterization. The [FeII-O-Si]+ in Si-Fe(II)-III may stabilize the dichlorocarbene anion (˸CCl2−), which favors the transformation of CT to methane (9.2%). The Si-Fe(II) co-precipitates consist of countless internal electric fields, and the transformation of hydroxyl and CT both consumed electrons. The coexistence of hydroxyl and CT increases the electron density in the electron-rich region due to their electronegativity, enhancing their electron-accepting capabilities. This study deepens our understanding of the phase composition and electronic structure of Si-Fe(II) co-precipitates, which fills the gap in the reductive dehalogenation of halides by Si-Fe(II) co-precipitates.