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Showing papers on "Charge density published in 2022"


Journal ArticleDOI
TL;DR: In this paper, a 2D/2D Mo2C/g-C3N4 Van der Waals (VDW) heterojunction photocatalyst was developed for typical PPCPs degradation.
Abstract: Pharmaceuticals and personal care products (PPCPs) are a large class of emerging contaminants. Here, we develop a 2D/2D Mo2C/g-C3N4 Van der Waals (VDW) heterojunction photocatalyst for typical PPCPs degradation. The 2D Mo2C shows unique electronic transport properties and allows the integration with other 2D materials for fabricating intriguing 2D interface. The Mo2C strongly coordinates with g-C3N4 to endow the ordered in-plane electron migration in g-C3N4 nanosheets and the VDW forces induce the electrons transfer within interlayers, building an internal electric field and stimulating the photogenerated charge kinetics. In addition, Mo2C can ameliorate the light absorption capacity and trap electrons to elongate the lifetimes of charge carriers. This synergy between VDW heterojunction and 2D structure engineering contributes to the superior photocatalytic activity for tetracycline degradation. Advanced characterizations, charge density based on density function theory calculations and the absence of charge transfer between layers confirm the VDW interactions between the individual components. This work provides a highly efficient and green strategy for typical PPCPs removal, and sheds lights on the construction of 2D/2D VDW heterojunction photocatalysts.

69 citations


Journal ArticleDOI
TL;DR: In this article , a rapid self-polarization effect of a polar dielectric material by the superhigh electric field in a charge-excitation TENG is reported, by which the permittivity of the polar material realizes self-increase to a saturation, and thus enhances the output charge density.
Abstract: Boosting output charge density is top priority for achieving high‐performance triboelectric nanogenerators (TENGs). The charge‐excitation strategy is demonstrated to be a superior approach to acquire high output charge density. Meanwhile, the molecular charge behaviors in the dielectric under a strong electric field from high charge density bring new physics that are worth exploring. Here, a rapid self‐polarization effect of a polar dielectric material by the superhigh electric field in a charge‐excitation TENG is reported, by which the permittivity of the polar dielectric material realizes self‐increase to a saturation, and thus enhances the output charge density. Consequently, an ultrahigh charge density of 3.53 mC m−2 is obtained with 7 µm homemade lead zirconate titanate−poly(vinylidene fluoride) composite film in the atmosphere with 5% relative humidity, which is the highest charge density for TENGs with high durability currently. This work provides new guidance for dielectric material optimization under charge excitation to boost the output performance of TENGs toward practical applications.

51 citations


Journal ArticleDOI
TL;DR: In this paper , an advanced heterostructure photocatalyst constructed by hexagonal boron nitride (h-BN) and flower-ring g-C3N4 (MCN) was successfully synthesized.

34 citations


Journal ArticleDOI
TL;DR: Using first principles density functional theory simulations, the authors observed that the scandium decorated C24 fullerene can adsorb up to six hydrogen molecules with an average adsorption energy of −0.35 eV per H2 and average desorption temperature of 451 K.

32 citations


Journal ArticleDOI
TL;DR: In this article , the first principle density functional theory calculations were performed on hexagonal boron nitride nanosheets (hBNNs) to investigate the adsorption of methylene blue (MB, cationic), methyl orange (MO, anionic) and neutral red (NR, neutral) dyes.

26 citations


Journal ArticleDOI
TL;DR: In this paper , a conjoined charge density wave (CDW) was realized in CsV 3 Sb 5 , where a 2 × 2 × 1 CDW in the kagome sublattice and a Sb L 1 -edge (2 s → 5 p ) at 2 ×2 × 2 CDW wavevectors were discovered.
Abstract: Abstract The electronic instabilities in CsV 3 Sb 5 are believed to originate from the V 3 d -electrons on the kagome plane, however the role of Sb 5 p -electrons for 3-dimensional orders is largely unexplored. Here, using resonant tender X-ray scattering and high-pressure X-ray scattering, we report a rare realization of conjoined charge density waves (CDWs) in CsV 3 Sb 5 , where a 2 × 2 × 1 CDW in the kagome sublattice and a Sb 5 p -electron assisted 2 × 2 × 2 CDW coexist. At ambient pressure, we discover a resonant enhancement on Sb L 1 -edge (2 s →5 p ) at the 2 × 2 × 2 CDW wavevectors. The resonance, however, is absent at the 2 × 2 × 1 CDW wavevectors. Applying hydrostatic pressure, CDW transition temperatures are separated, where the 2 × 2 × 2 CDW emerges 4 K above the 2 × 2 × 1 CDW at 1 GPa. These observations demonstrate that symmetry-breaking phases in CsV 3 Sb 5 go beyond the minimal framework of kagome electronic bands near van Hove filling.

20 citations


Journal ArticleDOI
TL;DR: In this article, two kinds of typical two-dimensional transition metal carbide and carbonitride (Ti3C2Tx) MXene were introduced into poly(vinylidene difluoride) (PVDF) ferroelectric polymers to achieve efficient dielectric modulation.

20 citations


Journal ArticleDOI
TL;DR: In this paper, the adsorption behavior of small gas molecules like CO, NO, CO2, NO2 and NH3 on Yttrium(Y) doped SnS2 monolayer by employing density functional theory simulations was investigated.
Abstract: In this work, we have investigated the adsorption behavior of small gas molecules like CO, NO, CO2, NO2 and NH3 on Yttrium(Y) doped SnS2 monolayer by employing density functional theory simulations. Y-doping effect on the physicochemical properties of the pure SnS 2 monolayer is first studied, then adsorption mechanism was analyzed by adsorption energy, charge transfer, structural properties, magnetic properties , electronic properties such as density of states, charge density and band structure. In addition, the transport properties are evaluated to propound the gas adsorption response of Yttrium (Y) doped -SnS 2 system on the device level. The result shows that all the gas molecules were strongly adsorbed on the Yttrium (Y) site of the Y-doped SnS2 monolayer through formation of strong covalent bonds and Y- doped SnS2 monolayers can be employed as a potential candidate for gas sensing applications. Here in, to evaluate the sensing capability, the molecular model of the adsorption systems was constructed, and density functional theory (DFT) was used to calculate the adsorption behavior of these gases.

19 citations


Journal ArticleDOI
TL;DR: In this article , the atomic structure-chemical bonding-property correlations in a series of perovskite-HEOs utilizing the recently developed four-dimensional scanning transmission electron microscopy techniques are analyzed.
Abstract: Abstract The enhanced compositional flexibility to incorporate multiple-principal cations in high entropy oxides (HEOs) offers the opportunity to expand boundaries for accessible compositions and unconventional properties in oxides. Attractive functionalities have been reported in some bulk HEOs, which are attributed to the long-range compositional homogeneity, lattice distortion, and local chemical bonding characteristics in materials. However, the intricate details of local composition fluctuation, metal-oxygen bond distortion and covalency are difficult to visualize experimentally, especially on the atomic scale. Here, we study the atomic structure-chemical bonding-property correlations in a series of perovskite-HEOs utilizing the recently developed four-dimensional scanning transmission electron microscopy techniques which enables to determine the structure, chemical bonding, electric field, and charge density on the atomic scale. The existence of compositional fluctuations along with significant composition-dependent distortion of metal-oxygen bonds is observed. Consequently, distinct variations of metal-oxygen bonding covalency are shown by the real-space charge-density distribution maps with sub-ångström resolution. The observed atomic features not only provide a realistic picture of the local physico-chemistry of chemically complex HEOs but can also be directly correlated to their distinctive magneto-electronic properties.

18 citations


Journal ArticleDOI
TL;DR: In this article, the surface charge density of nickel-iron layered double hydroxide (NiFe LDH) is tuned through iron valence change to improve the performance in adsorption of hexavalent chromium (Cr(VI)).

18 citations


Journal ArticleDOI
TL;DR: In this article , the surface charge density of nickel-iron layered double hydroxide (NiFe LDH) is tuned through iron valence change to improve the performance in adsorption of hexavalent chromium (Cr(VI)).

Journal ArticleDOI
TL;DR: In this article, a controllable phosphorization strategy was proposed to construct phosphorus-rich and metal-rich (Fe, Ni)3P/NiCoP heterojunction arrays to tune the hydrogen binding energy.

Journal ArticleDOI
TL;DR: A general framework for assessing the role of the CP and CR mechanisms in existing case studies and for predicting how various proteins interact with polyelectrolytes at different pH values is developed.
Abstract: The mechanism of protein-polyelectrolyte complexation on the wrong side of the isoelectric point has long puzzled researchers. Two alternative explanations have been proposed in the literature: (a) the charge-patch (CP) mechanism, based on the inhomogeneous distribution of charges on the protein, and (b) the charge-regulation (CR) mechanism, based on the variable charge of weak acid and base groups, which may invert the protein charge in the presence of another highly charged object. To discern these two mechanisms, we simulated artificially constructed short peptides, containing acidic and basic residues, arranged in a blocklike or alternating sequence. Our simulations of these peptides, interacting with polyelectrolytes, showed that charge patch and charge regulation alone can both lead to adsorption on the wrong side of the pI value. Their simultaneous presence enhances adsorption, whereas their absence prevents adsorption. Our simulation results were rationalized by following the variation of the charge regulation capacity and dipole moments of these peptides with the pH. Specifically for lysozyme, we found that charge patch prevails at physiological pH, whereas charge regulation prevails near the pI, thereby explaining seemingly contradicting conclusions in the literature. By applying the same approach to other proteins, we developed a general framework for assessing the role of the CP and CR mechanisms in existing case studies and for predicting how various proteins interact with polyelectrolytes at different pH values.


Journal ArticleDOI
TL;DR: In this article , the effect of divalent counterions on the membrane charge density was investigated in multi-component electrolytes solutions, and the results in this paper reinforce the idea that adsorption of counterions plays a fundamental role in the performance of nanofiltration.

Journal ArticleDOI
TL;DR: In this article , the ion current rectification (ICR) performance in the bilayer nanochannel with non-uniform charge distribution was investigated and the results showed that asymmetrical geometry without the surface charge cannot induce ICR and the existence of surface charge is necessary.

Journal ArticleDOI
TL;DR: In this article , a review of X-ray charge density analysis in the field of non-covalent interactions involving elements of the groups 14-17 of the periodic table is presented.
Abstract: The work carried out by our research group over the last couple of decades in the context of quantitative crystal engineering involves the analysis of intermolecular interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding using experimental charge density methodology is reviewed. The focus is to extract electron density distribution in the intermolecular space and to obtain guidelines to evaluate the strength and directionality of such interactions towards the design of molecular crystals with desired properties. Following the early studies on halogen bonding interactions, several “sigma-hole” interaction types with similar electrostatic origins have been explored in recent times for their strength, origin, and structural consequences. These include interactions such as carbon (tetrel) bonding, pnicogen bonding, chalcogen bonding, and halogen bonding. Experimental X-ray charge density analysis has proved to be a powerful tool in unraveling the strength and electronic origin of such interactions, providing insights beyond the theoretical estimates from gas-phase molecular dimer calculations. In this mini-review, we outline some selected contributions from the X-ray charge density studies to the field of non-covalent interactions (NCIs) involving elements of the groups 14–17 of the periodic table. Quantitative insights into the nature of these interactions obtained from the experimental electron density distribution and subsequent topological analysis by the quantum theory of atoms in molecules (QTAIM) have been discussed. A few notable examples of weak interactions have been presented in terms of their experimental charge density features. These examples reveal not only the strength and beauty of X-ray charge density multipole modeling as an advanced structural chemistry tool but also its utility in providing experimental benchmarks for the theoretical studies of weak interactions in crystals.

Journal ArticleDOI
TL;DR: In this paper , a self-polarization effect-based charge-excitation TENG (SP-CE-TENG) is proposed with high surface charge density (SCD), and the charge self-increase phenomenon of dielectric materials with different strong polar groups is investigated.

Journal ArticleDOI
TL;DR: In this paper , a controllable phosphorization strategy was proposed to construct phosphorus-rich and metal-rich (Fe, Ni)3P/NiCoP heterojunction arrays to tune the hydrogen binding energy.

Journal ArticleDOI
TL;DR: In this article , a fast surface charge injection technique based on air breakdown effect is reported, which utilizes an excitation circuit to realize the directional accumulation of charge, and the output charge density of the Polyimide (PI) film after charge injection reaches 880 µC m−2, which is the highest of the series of modified triboelectric materials.
Abstract: The modification of triboelectric materials is an important means to improve the output performance of triboelectric nanogenerator (TENG), and the surface charge or ion implantation is an effective way among many modification methods. However, the output enhancement via optimizing triboelectric materials is still limited. Herein, a fast surface charge injection technique based on air breakdown effect is reported, which utilizes an excitation circuit to realize the directional accumulation of charge. Consequently, the output charge density of the Polyimide (PI) film after charge injection reaches 880 µC m‐2, which is the highest of the series of modified triboelectric materials. Moreover, a novel charge transfer mechanism with electrostatic induction competition is proposed, in which significant difference between surface charge density and output charge density is highlighted clearly. Meanwhile, the method of quantifying surface charge density is further given. This work provides a more effective method for the modification of dielectric materials and also offers an important insight towards the charge transfer mechanism in TENG.

Journal ArticleDOI
TL;DR: In this paper , the authors proposed a model based on the density of surface states (DOSS) as another key contributing factor to the triboelectric charge generation, which may provide a more complete model for guiding the material selection and modification to tailor the surface charge generated by the contact electrification.
Abstract: The triboelectric nanogenerator (TENG) has been invented as a technology for harvesting mechanical energy, as well as for allocating quantized charge for scientific instruments. The charge generation of the TENG is mainly related to the triboelectric effect or contact electrification (CE) as usually described by the potential-well-electron-cloud model, while the triboelectric charge transfer is related to the difference in the occupied energy levels of electrons. However, in our experiment, we observed an abnormal triboelectric charge generation phenomena between ternary materials, which cannot be explained by the occupied energy level difference only. To address this issue, we proposed the model based on the density of surface states (DOSS) as another key contributing factor to the triboelectric charge generation. To demonstrate our model, we introduced an approach to measure the DOSS through applying external electric field between two triboelectric surfaces. Our experiments confirmed the contribution of the DOSS to the triboelectric charge generation, with the derived charge density consistent with the measured results, which verified our model. We also predicted that the FEP has the potential to achieve a high charge density of ∼5.6 × 10-4 C/m2, which is close to the reported maximum values. This study provides another key contributing factor to the triboelectric charge generation, which may provide a more complete model for guiding the material selection and modification to tailor the surface charge generated by the CE.

Journal ArticleDOI
TL;DR: In this paper , the density and charge distribution and the flow behavior of [EMIM][BF4] blended with water as diluent and imposed electric field in nanochannel were studied using molecular dynamic simulation method.

Journal ArticleDOI
01 Feb 2022-Fuel
TL;DR: In this paper, the effect of multiple-membered carbocycle (MMC) on elemental mercury adsorption on the carbonaceous surface has been investigated and the results indicate that the distribution of C C bond lengths presents two different trends due to the influence of MMC.

Journal ArticleDOI
TL;DR: In this paper , a scanning tunneling microscopy (STM) and ab-initio study of the anisotropic superconductivity of 2H-NbSe 2 in the charge-density-wave (CDW) phase is presented.
Abstract: Abstract We present a scanning tunneling microscopy (STM) and ab-initio study of the anisotropic superconductivity of 2H-NbSe 2 in the charge-density-wave (CDW) phase. Differential-conductance spectra show a clear double-peak structure, which is well reproduced by density functional theory simulations enabling full k - and real-space resolution of the superconducting gap. The hollow-centered (HC) and chalcogen-centered (CC) CDW patterns observed in the experiment are mapped onto separate van der Waals layers with different electronic properties. We identify the CC layer as the high-gap region responsible for the main STM peak. Remarkably, this region belongs to the same Fermi surface sheet that is broken by the CDW gap opening. Simulations reveal a highly anisotropic distribution of the superconducting gap within single Fermi sheets, setting aside the proposed scenario of a two-gap superconductivity. Our results point to a spatially localized competition between superconductivity and CDW involving the HC regions of the crystal.

Journal ArticleDOI
TL;DR: In this article , the authors investigate the enhancement of ionic diffusion by charged exterior surfaces under various conditions and explore corresponding effective charged areas, where the effective widths of the charged ring regions near nanopores are reversely proportional to the pore length.
Abstract: High-performance osmotic energy conversion requires both large ionic throughput and high ionic selectivity, which can be significantly promoted by exterior surface charges simultaneously, especially for short nanopores. Here, we investigate the enhancement of ionic diffusion by charged exterior surfaces under various conditions and explore corresponding effective charged areas. From simulations, ionic diffusion is promoted more significantly by exterior surface charges through nanopores with a shorter length, wider diameter, and larger surface charge density or under higher salt gradients. Effective widths of the charged ring regions near nanopores are reversely proportional to the pore length and linearly dependent on the pore diameter, salt gradient, and surface charge density. Due to the important role of effective charged areas in the propagation of ionic diffusion through single nanopores to cases with porous membranes, our results may provide useful guidance to the design and fabrication of porous membranes for practical high-performance osmotic energy harvesting.

Journal ArticleDOI
TL;DR: In this article, the effects of hydrostatic pressure on the electronic and thermoelectric properties of n-type halide perovskite CsSnI3 have been investigated using first-principles approach with spin-orbit coupling included.

Journal ArticleDOI
TL;DR: In this paper , a comprehensive study on the sensitivity of graphene, boron nitride, silicon carbide and their in-plane hetero-sheets towards carbon monoxide (CO) was performed using first-principle density functional theory calculations.

Journal ArticleDOI
TL;DR: In this paper , the microstructural features and charge-potential relation of an electric double layer (EDL) at a stepped Pt(553)/water interface were investigated using ab initio molecular dynamics simulation.
Abstract: The microstructural features and charge-potential relation of an electric double layer (EDL) at a stepped Pt(553)/water interface are investigated using ab initio molecular dynamics simulation. The results indicate that the chemisorbed O-down water molecules gather at the (110) step sites, while the (111) terrace sites are covered by the H-down water molecules, which greatly weakens the push-back effect of interface water on the spillover electrons of the stepped surface and, therefore, results in a much more positive potential of zero charge (PZC) than the extended low-index Pt surfaces. It is further revealed that around the PZC, the change in the surface charge density is dominated by the change in the coverage of chemisorbed water molecules, while EDL charging is the main cause of the change in the surface charge density at potential away from the PZC, thus leading to an S-shaped charge-potential relation and a maximum interface capacitance around PZC. Our results make up for the current lack of the atomic-scale understanding of the EDL microstructures and charge-potential relation on the real electrode surfaces with plentiful step and defect sites.

Journal ArticleDOI
05 Jul 2022-Small
TL;DR: In this article , a ferromagnetic-based charge-accumulation TENG (FC-TENG) is proposed with ultra-high surface charge density and performances, which can shed a new insight and guidance on the high performance TENG for various environmental conditions such as the ocean, industrial manufacturing, aerospace, and rail traffic.
Abstract: An encouraging micro-energy harvesting technology, the triboelectric nanogenerator (TENG), has been proven to transfer ambient environmental micro-energy into electricity, but a low surface charge density results in low performance and limits the practical application of TENG. Here, a ferromagnetic-based charge-accumulation TENG (FC-TENG) is proposed with ultrahigh surface charge density and performances. The FC-TENG introduces a ferromagnetic media to enhance the output charge by magnetization effect. Meanwhile, the charge can also be continuously accumulated by the charge pump effects. Based on these two effects, an ultra-high surface charge density of 2.85 mC m-2 is obtained under ambient atmospheric conditions using an ultra-thin PET film (3 µm) and deposited Permalloy ferromagnetic electrodes. Meanwhile, the surface charge density of the FC-TENG can always maintain more than 1.5 mC m-2 , even if the relative humidity arrives at 90%. This work provides a prospective technical mode to enhance the surface charge density of TENG, which would shed a new insight and guidance on the high-performance TENG for various environmental conditions such as the ocean, industrial manufacturing, aerospace, and rail traffic.

Journal ArticleDOI
Xi Chen, Zuoqing Luo, Rui Long, Zhichun Liu, Wei Liu 
TL;DR: In this article , the performance of nanofluidic salinity gradient energy conversion is investigated, where the solution pH at the high/low concentration side varies separately, rendering asymmetric pH configurations.