Intrinsic Electric Field Research Articles

Fabrication of a family of BiOI-doped copper-organic frameworks for enhancing photocatalytic degradation of dyes

Organic dyes are one of the most popular dyes used in industrial and consumption nowadays, and the use of dyes has certain hazards. One of the greenest and most efficient methods for breaking down organic contaminants is photocatalysis. It is a green technology that has enormous promise for the environment and energy sectors. In this work, p-type BiOI nanosheets were deposited in situ on n-type copper-based metal–organic framework (Cu-MOF) to create a unique BiOI@Cu-MOF heterojunction. The BiOI@Cu-5 heterojunction that is optimized showed nearly 100 % removal of rose Bengal (RB) under UV irradiation as well as the degradation rates of methyl orange (MO), crystal violet (GV), methylene blue (MB), and rhodamine B (RhB) were 99.70 %, 95.70 %, 27.20 %, and 23.90 %, respectively. First, the introduction of narrow bandgap BiOI into the material can effectively enhance its absorption of sunlight. Secondly, the high specific surface of the Cu-based MOFs material is favorable for improving the catalytic activity of the catalyst. More critically, the intrinsic electric field at the Cu-MOFs/BiOI heterojunction interface facilitates a successful division of photogenerated electron-hole pairs. Further studies revealed that the photogenerated holes are the important active ingredients for RB scavenging. In this paper, Bi-based semiconductors were used to create p-n heterostructures that will bring new ideas for increasing MOF photocatalytic activity.

Novel S-scheme β-Cu2V2O7/Ni/Pg-C3N4 heterojunction photocatalyst for sunlight-induced degradation of RhB

A novel S-scheme β-Cu2V2O7/Ni/Pg-C3N4 nanocomposite photocatalyst has been advantageously established by propelling β-Cu2V2O7 nanoparticles (NPs) on the top layer of porous graphitic carbon nitride (Pg-C3N4) nanosheets (NSs) using a facile co-precipitation approach. Implementing photoelectrochemical and physicochemical techniques, the crystallinity, purity, optical quality, morphology, chemical composition, and charge separation efficiency of the produced samples were examined. The outcomes indicate that metallic Ni and β-Cu2V2O7 NPs were perfectly encapsulated onto the Pg-C3N4 NSs and well-matched band structures between both semiconductors facilitate the creation of an S-scheme charge transfer path. The fabricated pristine and β-Cu2V2O7/Ni/Pg-C3N4 composite samples were utilized as a catalyst for the removal of rhodamine B (RhB) dye under sunlight irradiation. The β-Cu2V2O7/Ni/Pg-C3N4 nanocomposite exhibits exceptional activity within 60 min of radiation exposure (RhB- 98.56%), whereas β-Cu2V2O7 and Pg-C3N4 show reduced activity (RhB-34.4% and 45.68%). The favourable impact of S-scheme nanocomposite establishment boosted photocatalytic behavior using the intrinsic electric field among Pg-C3N4 NSs and β-Cu2V2O7 and surface plasmon resonance (SPR) effect of metallic Nickel (Ni) NPs for delivering e− and h+ pairs and prolonging the life of charge carriers. According to radical scavenging experiments •O2− is the primary reactive species followed by •OH radicals. The produced nanocomposite has the potential to be employed in large-scale photocatalytic water treatment, as evidenced by the photocatalyst's excellent efficiency and reusability after five consecutive experiments.

Modulation of Polarization in Sliding Ferroelectrics by Introducing Intrinsic Electric Fields.

The emergence of sliding ferroelectricity facilitates low-barrier ferroelectrics in two-dimensional materials, while limited electric polarizations impede practical applications. Herein, we propose an effective strategy to enlarge the polarization by introducing an intrinsic electric field, exemplified by Janus transition metal dichalcogenides (TMDs) with the first-principle calculations. The intrinsic electric field is introduced and regulated by leveraging the electronegativity differences among chalcogens. An improved polarization is achieved in the Janus TeMoS bilayer with a polarization of 1.18 pC/m, a 65% enhancement compared to normal TMD bilayers. Through differential charge density analysis, the inner mechanism is attributed to the effects of intrinsic electric fields on charge redistribution. Furthermore, the feasibility of polarization reversal is determined by evaluating switching barriers and the responses under an electric field. The provided proposal is applicable and available for broader systems and will pave the way for the development of novel electronic devices.

Enhanced photocatalytic activities of transition metal-doped BiOCl catalysts: A DFT and experimental study

The hierarchical architecture and non-uniform distribution of charges in the BiOCl photocatalyst can create an intrinsic electric field, which facilitates good separation and transfer of photogenerated carriers. However, BiOCl photocatalyst is not active in the visible-light region due to its wide bandgap, which hinders its photodegradation applications. In this study, we investigated six transition metals (Co, Ni, Fe, W, Mn, and Zr)-doped BiOCl via density functional theory (DFT) to screen excellent photocatalysts, among which Co–BiOCl showed the optimal catalytic performance. The incorporation of Co not only caused a redshift to its absorption band in BiOCl, but also introduced an inherent electric field, which further inhibited the charge carriers from recombination. These synergistic effects resulted in its improved stability and the enhancement photocatalytic degradation of pollutants, especially organic matter, in wastewater.

Excellent energy storage performance in BSFCZ/AGO/BNTN double-heterojunction capacitors via the synergistic effect of interface and dead-layer engineering

Dielectric films with ultra-high energy storage density and efficiency are urgently needed due to the energy crisis. Here, we construct novel ferroelectric/dead-layer/superparaelectric (FE/DL/SPE) double-heterojunction capacitors, utilizing interface and dead-layer engineering to achieve outstanding energy storage performance. Bi0.9Sm0.1Fe0.9Co0.05Zn0.05O3 (BSFCZ) with large polarization, Ba0.985Na0.015Ti0.95Ni0.05O3 (BNTN) with low hysteresis and high breakdown strength (Eb), and artificial Al0.9Ga0.1O3 (AGO) with wide band-gap were chosen as the FE, SPE, and DL phases, respectively. Interface engineering enables the BSFCZ/AGO/BNTN films to maintain a high polarization of 55 μC cm−2, while the linear dielectric AGO and SPE BNTN substantially suppresses the remnant polarization. This can be clarified by the evolution of domains in the BSFCZ layer: nanodomains are scaled down to polar clusters, reducing polarization hysteresis while maintaining relatively high polarization. Simultaneously, two opposing intrinsic electric fields are formed to offset a portion of the external electric field, and the low dielectric constant AGO layer bears a significant part of the applied electric field due to electromagnetic boundary conditions. Consequently, the Eb is significantly increased from 4.4 MV cm−1 of BSFCZ/BNTN to 5.5 MV cm−1 of BSFCZ/AGO/BNTN, resulting in a giant recoverable energy density of 132 J cm−3 and a high efficiency of 84 % in BSFCZ/AGO/BNTN films. Moreover, the BSFCZ/AGO/BNTN films excel in temperature stability (RT∼200 °C), fatigue resistance (up to 107 cycles), and frequency stability (200 Hz to 20 kHz), alongside an exceptionally rapid discharge rate of 2.6 μs. This innovative approach suggests new possibilities for producing environmentally friendly, large-area, high-performance dielectric capacitors.

Novel furan-containing linear polymer with strong built-in electric field for H2O2 photosynthesis

Using oxygen and water as raw materials, the photocatalytic production of H2O2 is a promising pathway. However, the limited charge separation efficiency represents a significant challenge in the photocatalysis field, as it impedes the generation of H2O2. Herein, a novel highly crystalline linear polymer has been synthesized here by bridging the strongly electronegative furan group with a diphenyl group, in order to adjust its molecular dipole moment to construct an intrinsic electric field to optimize photocatalytic performance. The optimal sample exhibited the best H2O2 synthesis rate of 2686 μmol·g−1·h−1 under pure water conditions, which is the best-performing linear conjugated polymer reported to date for H2O2 photosynthesis system. Importantly, the large internal dipole moment within furan-diphenyl linear polymer, together with the ordered crystalline structure induced robust built-in electric field, can facilitate migration and separation of photogenerated charge carriers. Manipulating molecular dipoles to enhance the built-in electric field can significantly improve photocatalytic activity, providing a new perspective for the rational design of functional linear conjugated polymers in green chemistry and sustainable production.

First-Principles Computational Screening of Two-Dimensional Polar Materials for Photocatalytic Water Splitting.

The band gap constraint of the photocatalyst for overall water splitting limits the utilization of solar energy. A strategy to broaden the range of light absorption is employing a two-dimensional (2D) polar material as photocatalyst, benefiting from the deflection of the energy level due to their intrinsic internal electric field. Here, by using first-principles computational screening, we search for 2D polar semiconductors for photocatalytic water splitting from both ground- and excited-state perspectives. Applying a unique electronic structure model of polar materials, there are 13 photocatalyst candidates for the hydrogen evolution reaction (HER) and 8 candidates for the oxygen evolution reaction (OER) without barrier energies from the perspective of the ground-state free energy variation calculation. In particular, Cu2As4Cl2S3 and Cu2As4Br2S3 can catalyze HER and OER simultaneously, becoming promising photocatalysts for overall water splitting. Furthermore, by combining ground-state band structure calculations with excited-state charge distribution and transfer calculated by linear-response time-dependent density functional theory (LR-TDDFT) and time-dependent ab initio nonadiabatic molecular dynamics (NAMD), respectively, the rationality of the 2D polar material model has been manifested. The intrinsic built-in electric field promotes the separation of charge carriers while suppressing their recombination. Therefore, our computational work provides a high-throughput method to design high-performance photocatalysts for water splitting.

Steering Geometric Reconstruction of Bismuth with Accelerated Dynamics for CO2 Electroreduction.

Bismuth-based materials have emerged as promising catalysts in the electrocatalytic reduction of CO2 to formate. However, the reasons for the reconstruction of Bi-based precursors to form bismuth nanosheets are still puzzling, especially the formation of defective bismuth sites. Herein, we prepare bismuth nanosheets with vacancy-rich defects (V-Bi NS) by rapidly reconstructing Bi19Cl3S27 under negative potential. Theoretical analysis reveals that the introduction of chlorine induces the generation of intrinsic electric field in the precursor, thereby increasing the electron transfer rate and further promoting the metallization of trivalent bismuth. Meanwhile, experimental tests verify that Bi19Cl3S27 has a faster reconstruction rate than Bi2S3. The formed V-Bi NS exhibits up to 96 % HCOO- Faraday efficiency and 400 mA cm-2 HCOO- partial current densities, and its electrochemical active surface area normalized formate current density and yield are 2.2 times higher than those of intact bismuth nanosheets (I-Bi NS). Density functional theory calculations indicate that bismuth vacancies with electron-rich aggregation reduce the activation energy of CO2 to *CO2 - radicals and stabilize the adsorption of the key intermediate *OCHO, thus facilitating the reaction kinetics of formate production.

Steering Geometric Reconstruction of Bismuth with Accelerated Dynamics for CO2 Electroreduction

AbstractBismuth‐based materials have emerged as promising catalysts in the electrocatalytic reduction of CO2 to formate. However, the reasons for the reconstruction of Bi‐based precursors to form bismuth nanosheets are still puzzling, especially the formation of defective bismuth sites. Herein, we prepare bismuth nanosheets with vacancy‐rich defects (V‐Bi NS) by rapidly reconstructing Bi19Cl3S27 under negative potential. Theoretical analysis reveals that the introduction of chlorine induces the generation of intrinsic electric field in the precursor, thereby increasing the electron transfer rate and further promoting the metallization of trivalent bismuth. Meanwhile, experimental tests verify that Bi19Cl3S27 has a faster reconstruction rate than Bi2S3. The formed V‐Bi NS exhibits up to 96 % HCOO− Faraday efficiency and 400 mA cm−2 HCOO− partial current densities, and its electrochemical active surface area normalized formate current density and yield are 2.2 times higher than those of intact bismuth nanosheets (I‐Bi NS). Density functional theory calculations indicate that bismuth vacancies with electron‐rich aggregation reduce the activation energy of CO2 to *CO2− radicals and stabilize the adsorption of the key intermediate *OCHO, thus facilitating the reaction kinetics of formate production.

Effect of different contact interfaces on electronic and optical properties in the heterojunction of SiC2/MoSSe

We investigate the effect of different contact interfaces on the electronic and optical characteristics of the SiC2/MoSSe heterojunction. It is found that SiC2/MoSSe(S) heterojunction is an indirect band gap semiconductor with type II band alignment. The SiC2/MoSSe (Se) heterojunction is a direct band gap semiconductor with a type Ⅰ band alignment. The difference in electronic properties between the two heterostructures comes from the different orientations of the intrinsic electric field of Janus MoSSe in the heterojunction. The band gap and energy band alignment are modulated under the applied electric field. Moreover, the optical properties of SiC2/MoSSe (Se) are better than the SiC2/MoSSe(S), and the applied electric field can improve the optical properties of the heterojunction. The results provide a potential way for efficient photovoltaic materials.

Boosting visible-light-driven photocatalytic H2 production by optimizing surface hydrogen desorption of NiS/CdS–P photocatalyst

Metal chalcogenides are regarded as favorable H2-evolution cocatalysts; however, they often exhibit unfavorable H desorption characteristics due to the strong affinity of nascent H and highly electronegative S sites, which significantly inhibit H2 generation. To address this issue, a general approach to electron-enriched control of sulfur-active sites is developed for weakening the strong interaction of S–H bonds. This is achieved through the formation of a nanostructured model composed of NiS/CdS–P, in which the surface phosphorus (P) atoms are incorporated in CdS NRs to create an imbalanced charge distribution and a localized built-in electric field in the crystal structure of CdS. In this situation, the built-in electric field not only separates the photogenerated electron hole pairs, but it also accelerates the photogenerated electrons from the CdS–P conduction band to the NiS surface for rapid hydrogen reduction rather than hydrogen adsorption. Photocatalytic tests show that the resultant NiS/CdS–P photocatalyst displays a significant H2-generation rate of 44.39 mmol g−1 h−1 and an apparent quantum efficiency of 41% at 420 nm. Valance band XPS analysis shows that CdS–P has a higher electron density than CdS, leading to the production of electron-rich Sδ− active centers. This better photocatalytic hydrogen generation might be due to the synergistic impact of tailoring the intrinsic built-in electric field for the acceleration of photogenerated charges by P-doping and the fabrication of a NiS cocatalyst for hydrogen reduction rather than hydrogen adsorption. The concept of optimizing the electron densities of active sites by morphology tailoring, with an extra built-in electric field, gives a method for rationally constructing artificial photocatalysts for solar power conversion.

Acceleration of bulk and surface charger transfer dynamics via FePi cocatalyst-coated Ti/(Sb)-Fe2O3:Sb/(Ti)-Fe2O3 type-II homojunction photoanode for photoelectrochemical performance

Hematite (α-Fe2O3) possesses notable benefits in the field of photoelectrochemical (PEC) water splitting. However, the overall low efficiency of the separation and transfer of photogenerated charge carriers significantly hinders its further utilization. Although the occurrence of an internal electric field has the potential to significantly augment the efficiency of charge separation and transfer, there is a crucial need to broaden the scope of its successful application. This study explores a strategy for modifying the coupling between homojunction formation with gradient doping and cocatalyst modification on hematite to boost PEC performance. The developed type II Ti-doped/(Sb-codoped) Fe2O3:Sb-doped/(Ti-codoped) Fe2O3 (Ti/(Sb)-HT:Sb/(Ti)-HT) homojunction with a staggered band alignment accelerated the bulk charge separation via an intrinsic built-in electric field, while the bulk conductivity was improved using a gradient co-doping approach. Furthermore, the deposition of a FePi cocatalyst expedited the transfer of holes from the photoanode to the electrolyte by increasing the surface states, thereby hastening the water oxidation kinetics. The resulting Ti/(Sb)-HT:Sb/(Ti)-HT@FePi photoanode exhibited a 78.7% increase in photocurrent density compared to the bare Ti-Fe2O3 photoanode (0.94–1.68 mA/cm2 at 1.23 VRHE), accompanied by a charge transfer efficiency of 72.5%. Comprehensive photoelectrochemical investigations revealed that the homojunction and cocatalyst play a vital role in improving the dynamics of both the bulk and surface of the hematite photoanode, thereby facilitating efficient water oxidation. These findings offer a deeper insight into the function of homojunction photoanodes adorned with cocatalysts in the solar water-splitting process.

Structural Dynamics of the Methyl-Coenzyme M Reductase Active Site Are Influenced by Coenzyme F430 Modifications.

Methyl-coenzyme M reductase (MCR) is a central player in methane biogeochemistry, governing methanogenesis and the anaerobic oxidation of methane (AOM) in methanogens and anaerobic methanotrophs (ANME), respectively. The prosthetic group of MCR is coenzyme F430, a nickel-containing tetrahydrocorphin. Several modified versions of F430 have been discovered, including the 172-methylthio-F430 (mtF430) used by ANME-1 MCR. Here, we employ molecular dynamics (MD) simulations to investigate the active site dynamics of MCR from Methanosarcina acetivorans and ANME-1 when bound to the canonical F430 compared to 172-thioether coenzyme F430 variants and substrates (methyl-coenzyme M and coenzyme B) for methane formation. Our simulations highlight the importance of the Gln to Val substitution in accommodating the 172 methylthio modification in ANME-1 MCR. Modifications at the 172 position disrupt the canonical substrate positioning in M. acetivorans MCR. However, in some replicates, active site reorganization to maintain substrate positioning suggests that the modified F430 variants could be accommodated in a methanogenic MCR. We additionally report the first quantitative estimate of MCR intrinsic electric fields that are pivotal in driving methane formation. Our results suggest that the electric field aligned along the CH3-S-CoM thioether bond facilitates homolytic bond cleavage, coinciding with the proposed catalytic mechanism. Structural perturbations, however, weaken and misalign these electric fields, emphasizing the importance of the active site structure in maintaining their integrity. In conclusion, our results deepen the understanding of MCR active site dynamics, the enzyme's organizational role in intrinsic electric fields for catalysis, and the interplay between active site structure and electrostatics.

Efficient photocatalytic CO2 reduction to CH4 via electric field-regulated d-band center on Ga2S3/CuS S-type heterojunction interface structures

Photocatalytic CO2 reduction is an excellent method for the resource utilization of CO2. However, challenges such as inferior product yields and poor selectivity still exist. In this investigation, a novel composite catalyst of S-type heterojunction Ga2S3/CuS was formulated and synthesized using a facile two-step hydrothermal method. The CH4 product yield of 30 wt% Ga2S3/CuS reached 18.8 μmol·g−1·h−1. The reaction pathways were investigated through in-situ DRIFTS and DFT calculations, revealing the internal built-in electric field at the S-type heterojunction induces migration of the Cu atomic d-band center towards the Fermi energy level. The elevation of the Cu d orbital energy levels enables electron contributions from the dxz orbital to facilitate the formation of π* bonds with CO2, thereby promoting the adsorption of both CO2 and intermediate species to produce CH4. This study emphasizes the influence of the intrinsic electric field at the interface on product yield and selectivity.

Enhancing GaN/AlxGa1-xN-Based Heterojunction Phototransistors: The Role of Graded Base Structures in Performance Improvement.

This research explores the architecture and efficacy of GaN/AlxGa1-xN-based heterojunction phototransistors (HPTs) engineered with both a compositionally graded and a doping-graded base. Employing theoretical analysis along with empirical fabrication techniques, HPTs configured with an aluminum compositionally graded base were observed to exhibit a substantial enhancement in current gain. Specifically, theoretical models predicted a 12-fold increase, while experimental evaluations revealed an even more pronounced improvement of approximately 27.9 times compared to conventional GaN base structures. Similarly, HPTs incorporating a doping-graded base demonstrated significant gains, with theoretical predictions indicating a doubling of current gain and experimental assessments showing a 6.1-fold increase. The doping-graded base implements a strategic modulation of hole concentration, ranging from 3.8 × 1016 cm-3 at the base-emitter interface to 3.8 × 1017 cm-3 at the base-collector junction. This controlled gradation markedly contributes to the observed enhancements in current gain. The principal mechanism driving these improvements is identified as the increased electron drift within the base, propelled by the intrinsic electric field inherent to both the compositionally and doping-graded structures. These results highlight the potential of such graded base designs in enhancing the performance of GaN/AlxGa1-xN HPTs and provide crucial insights for the advancement of future phototransistor technologies.

Interlayer excitons in WSO/MoSi2N4 heterostructures

The intrinsic electric field of Janus layer has an important impact on interlayer excitons of heterostructures constructed by Janus components. In this study, we employ the GW-BSE method to investigate the influence of the intrinsic electric field on interlayer excitons in WSO/MoSi2N4 heterostructures with different stacking configurations. Our findings reveal that reverse the Janus WSO layer strongly alters the electronic structures while keeping the type-Ⅱ band alignment feature. Both structures demonstrate tightly bound bright interlayer excitons. We also observe that the lowest energy interlayer bright exciton (IXB) in 1-WSO has a higher percentage of allowed transitions compared to 2-WSO, due to the multi-band transition characteristic of the participating states. And thus the intrinsic electric field facilitates the transition of IXB in 1-WSO. Consequently, the radiative lifetime of the IXB is extremely short, around 10−10 s at 300 K. Our exploration underscores the significance of the intrinsic electric field in determining the lifetime of IXs.

Regioselective enzymatic depolymerization of aromatic-aliphatic polyester revealed by computational modelling

Poly(butylene adipate-co-terephthalate) (PBAT) is widely utilized in the production of food packaging and mulch films. Its extensive application has contributed significantly to global solid waste, posing numerous environmental challenges. Recently, enzymatic recycling has emerged as a promising eco-friendly solution for the management of plastic waste. Here, we systematically investigate the depolymerization mechanism of PBAT catalyzed by cutinase TfCutSI with molecular docking, molecular dynamics simulations, and quantum mechanics/molecular mechanics calculations. Although the binding affinities for acid ester and terephthalic acid ester bonds are similar, a regioselective depolymerization mechanism and a “chain-length” effect on regioselectivity were proposed and evidenced. The regioselectivity is highly associated with specific structural parameters, namely Substrate@O4-Met@H7 and Substrate@C1-Ser@O1 distances. Notably, the binding mode of BTa captured by X-ray crystallography does not facilitate subsequent depolymerization. Instead, a previously unanticipated binding mode, predicted through computational analysis, is confirmed to play a crucial role in BTa depolymerization. This finding proves the critical role of computational modelling in refining experimental results. Furthermore, our results revealed that both the hydrogen bond network and enzyme’s intrinsic electric field are instrumental in the formation of the final product. In summary, these novel molecular insights into the PBAT depolymerization mechanism offer a fundamental basis for enzyme engineering to enhance industrial plastic recycling.

Tuning Charge-Transfer States by Interface Electric Fields.

Intermolecular charge-transfer (CT) states are extended excitons with a charge separation on the nanometer scale. Through absorption and emission processes, they couple to the ground state. This property is employed both in light-emitting and light-absorbing devices. Their conception often relies on donor-acceptor (D-A) interfaces, so-called type-II heterojunctions, which usually generate significant electric fields. Several recent studies claim that these fields alter the energetic configuration of the CT states at the interface, an idea holding prospects like multicolor emission from a single emissive interface or shifting the absorption characteristics of a photodetector. Here, we test this hypothesis and contribute to the discussion by presenting a new model system. Through the fabrication of planar organic p-(i-)n junctions, we generate an ensemble of oriented CT states that allows the systematic assessment of electric field impacts. By increasing the thickness of the intrinsic layer at the D-A interface from 0 to 20 nm and by applying external voltages up to 6 V, we realize two different scenarios that controllably tune the intrinsic and extrinsic electric interface fields. By this, we obtain significant shifts of the CT-state peak emission of about 0.5 eV (170 nm from red to green color) from the same D-A material combination. This effect can be explained in a classical electrostatic picture, as the interface electric field alters the potential energy of the electric CT-state dipole. This study illustrates that CT-state energies can be tuned significantly if their electric dipoles are aligned to the interface electric field.

Tailoring the quantum anomalous layer Hall effect in multiferroic bilayers through sliding

Layer Hall effect (LHE), initially discovered in the magnetic topological insulator MnBi2Te4 film, expands the Hall effect family and opens a promising avenue for layertronics applications. In this study, we present an innovative ferroelectric bilayer model to attain a tunable quantum anomalous layer Hall effect (QALHE). This model comprises two ferromagnetic orbital-active Dirac monolayers stacked antiferromagnetically, accompanied by out-of-plane electric polarization. The interplay between the layer-locked Berry curvature monopoles and the intrinsic out-of-plane electric polarization leads to layer-polarized near-quantized anomalous Hall conductance. Using first-principles calculations, we have identified a promising material for this model, namely FeS bilayer. Our calculations demonstrate that the intrinsic out-of-plane electric polarization in the Bernal-stacked FeS bilayer can induce QALHE by regulating the layer-locked Berry curvature of FeS monolayers. Importantly, the intrinsic electric field can be reversed through interlayer sliding. The discovery of ferroelectrically modulated QALHE paves the way for the integrability and non-volatility of layertronics, offering exciting prospects for future applications.

Water Microdroplets in Air: A Hitherto Unnoticed Natural Source of Nitrogen Oxides.

Water microdroplets are widespread in the atmosphere. We report a striking observation that micron-sized water droplets obtained from zero-volt spray sources (sonic spray, humidifier, spray bottle, steamer, etc.) spontaneously generate nitrogen oxides. The mechanistic investigation through the development of custom-designed sampling sources combined with mass spectrometry and isotope labeling experiments confirmed that air nitrogen reacts with the water at the air-water interface, fixing molecular nitrogen to its oxides (NO, NO2, and N2O) and acids (HNO2 and HNO3) at trace levels without any catalyst. These reactions are attributed to the consequence of an experimentally detected feeble corona discharge (breakdown of air) at the air-water interface, likely driven by the high intrinsic electric field at the surface of water microdroplets. The extent of this corona discharge effect varies depending on the pH, salinity/impurity, size, speed, and lifetime of microdroplets in the air. Thus, this study discloses that the air-water interface of microdroplets breaks the strong chemical bond of nitrogen (N2), producing nitrogen oxides in the environment, while lightning strikes and microbial processes in soil are considered their dominant natural sources. As nitrogen oxides are toxic air pollutants, their spontaneous formation at the air-water interface should have important implications in atmospheric reactions, requiring further investigations.