Electron Transport Mechanism Research Articles

Late-model Bi-MOF＆CdS-QDs materials: Excellent properties and performance in PEC sensors for lung cancer markers

Herein, a novel photoelectrochemical (PEC) active material based on Bi-MOF&CdS-QDs (B&C) is prepared for the first time. Concurrently, a novel form of ultrasensitive PEC biosensor is created for the purpose of detecting CYFRA21-1. The improvement of B&C photocurrent activity is due to the “II-type” electron transport mechanism between Bi-MOF and CdS-QDs. PEC platform is built on B&C modified electrode. The CYFRA21-1 antibody (Ab) is further associated with B&C; bovine serum albumin (BSA) blocks the non-specific binding site. Finally, CYFRA21-1 antigen (Ag) was modified by Ag-Ab specific recognition reaction. Photocurrent signals are suppressed because biological macromolecules are intrinsically insulated. This method enables extremely sensitive CYFRA21-1 detection. The linear range of the PEC biosensor used for CYFRA21-1 detection is 0.0001 ∼ 100 ng·mL−1, and the detection limit is as low as 300 fg·mL−1. This is the first reported PEC immunosensor based on Bi-MOF. The findings indicate that this approach offers a viable platform for sensitive detection of CYFRA21-1.

Electrical transport properties of Cu2ZnSnSe4 thin films for solar cells applications

In this work we study the electrical transport properties of Cu2ZuSnSe4 (CZTse) thin films. CZTSe thin films were prepared by PVD method; the parameters of deposition as substrate temperature (T,) and mass, (Mx), (Mx = ZnSe, Cu) were varied for a range wide. Conductivity and resistivity measurements as a function of temperature were obtained between 120 and 400 K. It was observed, that high-temperature range above room temperature (>300 K) the carrier transport is thermally activated, with a single activation energy that changes with the variation of T, and Mx. In the low-temperature range (<300 K)), variable range hopping (VRH) was established as a predominant electronic transport mechanism for all samples. Hoppmg parameters were obtained by Difíusinal model and percolation theory.

Multiparametric AFM insights into electron transport mechanisms in biomemristors

Biomemristors have attracted significant attention due to their applications in biodegradable and flexible electronic devices, and their prospective functions in information storage, neural synapses, and neuromorphic computation. Hence, understanding biomaterials' resistive switching (RS) mechanism is essential to design novel biomemristors with enhanced performance. In the last decade, various atomic force microscopy (AFM) modes, such as Kelvin probe force microscopy (KPFM) and conductive atomic force microscopy (cAFM), in situ/operando visualize the electron transport behaviors within biomemristors at the nanoscale. This review provides a comprehensive discussion of multiparametric AFM techniques to characterize biomemristors and inspire new ideas in developing next-generation consumer electronics. We also summarize the progress of revealing the internal mechanism of biomemristors with functional AFM to visualize and understand the switching behavior. Finally, the opportunities and challenges of further utilizing multiparametric AFM to explore the electron transport mechanisms in biomemristors are presented.

Synergistic degradation of formaldehyde and chlorophenols in N-CQDs/BiOBr photocathode-coupled microbial fuel cells and the enhancement of power production efficiency

p-Chlorophenol (4-CP) is a recalcitrant pollutant with high toxicity that bioaccumulates and persists in the environment. In order to remove most of 4-CP in a short time, this study constructed an N-CQDs/BiOBr photocatalytic cathode microbial fuel cell (PMFCs) system, introduced formaldehyde wastewater into the biological anode, and enhanced the electronic interaction between the cathode and anode, thus realizing the high efficiency of the degradation of 4-CP and the production of electric energy. The results showed that the removal rate of 4-CP (30 mg/L) by PMFCs was 86.8%, which was higher than that of MFC (65%) and photocatalysis (11.73%) combined, showing a good synergistic effect. In addition, driven by the continuous negative bias provided by the anode, the electrons generated at the anode preferentially combine with the photogenerated holes at the cathode, which increases the power generation of the PMFCs, and achieves a maximum power density of 286.225 W/ m2 and a maximum open-circuit voltage of 0.518 V. The electrochemical properties of PMFCs were characterized by cyclic voltammetry and electrochemical impedance spectroscopy, and the results showed that the charge transfer resistance of PMFCs was only half that of MFC. Free radical trapping experiments have confirmed that ∙O2- is the main reactive oxidizing substance. Subsequently, a possible electron transport mechanism was proposed, and five degradation pathways of 4-CP were identified using liquid chromatography-mass spectrometry. In conclusion, this technology is a good alternative method to improve the treatment efficiency of refractory wastewater in practical applications.

Study on the conductivity of metal-based epitaxial graphene with vacancy defects and anharmonic effects

Metal-based epitaxial graphene exhibits extremely high conductivity at room temperature, making the study of its conductance crucial for understanding electron transport mechanisms in two-dimensional materials. In this paper, we applied solid-state physics theories and methods to investigate factors influencing the conductivity of metal-based epitaxial graphene. We considered the variation of conductivity and its temperature stability coefficient with temperature, taking into account the anharmonic vibrations of atoms, and explored the impact of anharmonic effects on conductivity. Using copper-based graphene as an example, we established relationships between temperature and several key parameters: electronic conductivity (σe), conductivity contributed by electron–phonon interactions (σp), conductivity contributed by vacancy defects (σn), and total conductivity (σ), along with its temperature stability coefficient (ασ). All research results were obtained within the temperature range of 300 K to 1200 K. The study reveals that σ decreases nonlinearly as temperature increases, with a magnitude on the order of (Ω ∙ m)-1, which is approximately equal to σp. The conductivity of copper-based epitaxial graphene is found to be greater than that of lithium-based epitaxial graphene. The anharmonic effects of atomic vibrations increase σ, and this increase is more pronounced at higher temperatures. The temperature stability coefficient ασ rapidly decreases with increasing temperature before tending to a constant, indicating that conductivity exhibits better temperature stability at higher temperatures. This paper provides theoretical guidance for understanding electron transport characteristics of metal-based epitaxial graphene and contributes to the design and application of high-performance electronic devices.

Activity and stability of electrochemically reduced graphene oxide films for applications requiring mixed conductivity

A protonic and electronic conductor composed of partially reduced graphene oxide (GO) has been prepared by electrochemical methods. Conductivity measurements and detailed surface analysis by XPS, FTIR, and Raman methods show that the electrochemically reduced GO (ERGO), prepared under different reduction potentials, exhibits a unique dual (protonic and electronic) conductivity which is tunable by adjusting the surface conditions. Selected removal of the oxygenated groups, evolution of C(sp2)/C(sp3) hybrid carbon structure, and surface structure of ERGO can impact the protonic and electronic transport mechanisms. The ERGO samples reported here are ideal support materials with proper ratios of protonic and electronic transport. The as-prepared ionomer-free and flexible ERGO-supported Pt (Pt/ERGO) electrodes were characterized for oxygen reduction reaction (ORR) reactivity in acidic solution. The results showed not only higher electrochemical surface area (ECSA), but also improved mass activity towards ORR compared to conventional carbon supported Pt catalysts.

Extremely Stable Ag-Based Photonics, Plasmonic, Optical, and Electronic Materials and Devices Designed with Surface Chemistry Engineering for Anti-Tarnish.

Silver (Ag) metal-based structures are promising building blocks for next-generation photonics and electronics owing to their unique characteristics, such as high reflectivity, surface plasmonic resonance effects, high electrical conductivity, and tunable electron transport mechanisms. However, Ag structures exhibit poor sustainability in terms of device performance because harsh chemicals, particularly S2- ions present in the air, can damage their structures, lowering their optical and electrical properties. Here, the surface chemistry of Ag structures with (3-mercaptopropyl)trimethoxysilane (MPTS) ligands at room temperature and under ambient conditions is engineered to prevent deterioration of their optical and electrical properties owing to S2- exposure. Regardless of the dimensions of the Ag structures, the MPTS ligands can be applied to each dimension (0D, 1D, and 3D). Consequently, highly sustainable plasmonic effects (Δλ < 2nm), Fabry-Perot cavity resonance structures (Δλ < 2nm), reflectors (ΔRReflectance < 0.5%), flexible electrodes (ΔRelectrical < 0.1 Ω), and strain gauge sensors (ΔGF < 1), even in S2- exposing conditions is achieved. This strategy is believed to significantly contribute to environmental pollution reduction by decreasing the volume of electronic waste.

Revealing the Loss Mechanism of Chemically-Induced Hot Electron Transport.

Hot electrons are crucial for unraveling the intrinsic relationship between chemical reactions and charge transfer in heterogeneous catalysis. Significant research focused on real-time detection of reaction-driven hot electron flow (chemicurrent) to elucidate the energy conversion mechanisms, but it remains elusive because carrier generation contributes to only part of the entire process. Here, a theoretical model for quantifying the chemicurrent yield is presented by clarifying the contributions of hot carrier losses from the internal emission and multiple reflections. The experimental chemicurrent yield verifies our model with a reliable mean free path of hot electrons, emphasizing the importance of comprehensive consideration of the transport process besides hot electron generation. Moreover, Pt nanoparticles (NPs)-decorated Au/TiO2 is examined, showing the role of NPs-induced carrier losses in the performance of catalytic nanodiodes. These findings are expected to contribute to understanding the hot electron detection efficiency and designing nanodiodes with enhanced hot carrier flow and catalytic activity.

A Perspective on the Molecular Modeling of Electrolyte Decomposition Reactions for Solid Electrolyte Interphase Growth in Lithium‐Ion Batteries

AbstractThe solid electrolyte interphase (SEI) is a thin heterogeneous layer formed at the anode/electrolyte interface in lithium‐ion batteries as a consequence of the reduction of the electrolyte. The initial formation of the SEI inhibits the direct contact between the electrode and the electrolyte and thus protects the battery. However, the composition, structure, and size of the SEI evolve over time and the growth of the SEI is considered the primary mechanism leading to the gradual deterioration of the battery performance. Despite the importance of the SEI and its growth, the atomistic understanding of the underlying elementary reaction steps remains partial. Molecular modeling of the electrolyte decomposition is key to gain detailed insights that are complementary to experiments for the reactions occurring in this heterogenous interphase. In this perspective, the electron transport mechanisms are first described from the anode to the electrolyte through the SEI and highlight the importance of the inorganic/organic interface within the heterogeneous SEI: it is where the electrolyte decomposition reactions are likely to occur. Finally, a view is provided on the current progress on molecular modeling techniques (e.g., Density Functional Theory, force fields, machine learning potentials) of the SEI and the challenges each method faces.

Boosting photocatalytic NO oxidation mediated by high redox charge carriers from visible light-driven C3N4/UiO-67 S-scheme heterojunction photocatalyst

The construction of CN/UiO-67 (CNU) S-scheme heterojunction composites through in situ formation of UiO-67 on carbon nitride (C3N4) helps to address the limitations of carbon nitride (CN) in photocatalytic NO elimination. The optimized CNU3 demonstrates superior photocatalytic efficiency, which is attributed to electronic channels constructed by Zr-N bonds and S-scheme electron transport mechanism, effectively promoting the efficient separation of photogenerated charge carriers with high redox potentials. Density Functional Theory (DFT) calculations reveal redistributed electronic orbitals in CNU3, with progressive and continuous energy levels near the Fermi level, which bolsters electronic conduction. Comprehensive quenching experiments, Electron Paramagnetic Resonance (EPR), and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analyses highlight a synergistic interplay of electrons, holes, and superoxide radicals in CNU3, inhibiting the generation of toxic nitrogen oxide intermediates and culminating in highly efficient photocatalytic NO oxidation. This study not only elucidates the mechanisms underpinning the enhanced performance of CNU3 heterojunctions but also offers new perspectives on the preparation and interfacial charge separation of heterojunction photocatalysts.

Influence of varying carbon oxides concentrations on the selectivity of an electrical sensor utilizing graphene nanoribbons

We have considered a graphene nano ribbon-based two probe-device working on the principle of alteration of current-voltage (I–V) characteristic, upon interactions of its channel material with the adsorbed gas molecules. The analysis of sensing parameters alongside the electron transport mechanism was carried out by using density functional theory (DFT) formulated on the Hohenberg-Kohen paradigm in conjunction with the non-equilibrium green functions (NEGF) method. Electronic transport through similar work reported earlier reveals that the combination of these two techniques coordinates extremely well and yields convincing electronic results. The nanoribbon-based sensing device was employed to evaluate its capability to detect Carbon dioxide (CO2) and Carbon monoxide (CO) molecules. Analysis of the computed result reveals significant modifications in the electronic property of the device upon adsorption of carbon dioxide and carbon monoxide entities on the channel surface. One such significant and dramatic change in the characteristic that we observed is the nature of the channel that transforms from metallic to semi-metallic. Another observed change is the signal amplification capability relative to the pristine device. The signal gets amplified on increasing number of molecular entities from one to six.The transformation in sensor performance is additionally supported by examining variations in multiple parameters, including adsorption energy, charge transfer, differential resistance, and the figure of merit, also known as the peak-to-valley ratio (PVR). The investigation unveiled that the currently designed zigzag graphene nanoribbon (ZGNR) model exhibits high sensitivity to both CO2 and CO gases. This phenomenon is substantiated by the elevated adsorption energy, increased charge transfer, elevated peak-to-valley ratio (PVR), and heightened sensor response. The substantial sensor response, registering at a magnitude of 8.3, underscores the efficacy of the current system in detecting both low and high concentrations of CO and CO2 molecules. The current study emphasizes the notion that understanding the electronic and transport behaviour of zigzag graphene nanoribbons (ZGNR) and analogous materials could offer valuable insights for addressing the threat of environmental pollution.

Efficient photocatalytic degradation of antibiotics by binary heterojunction complex boron subphthalocyanine bromide/bismuth oxychloride

The development of stable and efficient heterojunction photocatalysts for wastewater environmental purification exhibits a significant challenge. Herien, a promising binary heterojunction complex comprising boron subphthalocyanine bromide/bismuth oxychloride (SubPc-Br/BiOCl) was successfully synthesized using the hydrothermal method, which involved the self-assembled of SubPc-Br on the surface of BiOCl via intermolecular π-π stacking interactions to compose an electron-transporting layer. The photocatalytic efficiency of SubPc-Br/BiOCl for the degradation of tetracycline and the minocycline exhibited a substantial improvement of 29.14% and 53.72%, respectively, compared to the original BiOCl. Experimental characterization and theoretical calculations elucidated that the enhanced photocatalytic performance of the SubPc-Br/BiOCl composite photocatalysts stemmed from the S-scheme electron transport mechanism at the interface between BiOCl and SubPc-Br supramolecules, which broadened the visible light absorption range, increased the carrier molecular efficiency, and accelerated the carriers. Furthermore, molecular dynamic (MD) simulations provided insights into the action trajectories of the two semiconductors, revealing that the presence of SubPc-Br enhances the water and organic pollutant adsorption capabilities of the BiOCl surface within the supramolecular array system. In conclusion, the synthesis and analysis of the binary heterojunction complex SubPc-Br/BiOCl yield valuable insights into the efficient photocatalytic degradation of antibiotics, holding great promise for diverse environmental applications.

Influence of electronic transport mechanism optimization on the thermoelectric properties of ZnO based functional ceramics

ZnO is one of the most promising mid-high temperature thermoelectric materials because of low cost, easy preparation and favorable chemical stability. Herein, the influence mechanism of Alkaline earth metal Ba doping on the thermoelectric properties of ZnO was studied. It is found that Ba doping can effectively improve the carrier mobility and electrical conductivity for that Ba doping can shorten the Zn–O bond and enhance the overlap and hybridization of electron orbitals. The electronic density of states of Zn and O is significantly enhanced. The highest power factor of ∼7.95 μWcm−1K−2 was obtained at 873 K, which is ∼1.4 times higher than that of the undoped sample. Due to the decrease of Young’s modulus caused by Ba doping and the enhancement of phonon scattering of heavy element, the thermal conductivity decreases obviously in the whole temperature range. Ba doping enhanced the effect of phonon glass-electron crystal, and the ZT value of ∼0.345 was obtained at 873 K, which is ∼3.52 times as that of the pristine ZnO. The results indicated that alkaline earth metal doping is an effective way to improve the thermoelectric properties of ZnO functional materials.

Analytical modeling of the electrical conductivity of CNT-filled polymer nanocomposites

Electrical conductivity of most polymeric insulators can be drastically enhanced by introducing a small volume fraction [Formula: see text] of conductive nanofillers. These nanocomposites find wide-ranging engineering applications from cellular metamaterials to strain sensors. In this work, we present a mathematical model to predict the effective electrical conductivity of carbon nanotubes (CNTs)/polymer nanocomposites accounting for the conductivity, dimensions, volume fraction, and alignment of the CNTs. Eshelby’s classical equivalent inclusion method (EIM) is generalized to account for electron-hopping—a key mechanism of electron transport across CNTs, and is validated with experimental data. Two measurements, namely, the limit angle of filler orientation and the probability distribution function, are used to control the alignment of CNTs within the composites. Our simulations show that decreasing the angle from a uniformly random distribution to a fully aligned state significantly reduces the transverse electrical conductivity, while the longitudinal conductivity shows less sensitivity to angle variation. Moreover, it is observed that distributing CNTs with non-uniform probability distribution functions results in an increase in longitudinal conductivity and a decrease in transverse conductivity, with these differences becoming more pronounced as the volume fraction of CNTs is increased. A reduction in CNT length decreases the effective electrical conductivity due to the reduced number of available conductive pathways while reducing CNT diameter increases the conductivity.

Tailoring Contacts for High-Performance 1D Ta2Pt3S8 Field-Effect Transistors.

Materials with van der Waals (vdW) unit structures rely on weak interunit vdW forces, facilitating physical separation and advancing nanomaterial research with remarkable electrical properties. Recently, there has been growing interest in one-dimensional (1D) vdW materials, celebrated for their advantageous properties, characterized by reduced dimensionality and the absence of dangling bonds. In this context, we synthesize Ta2Pt3S8, a 1D vdW material, and assess its suitability for field-effect transistor (FET) applications. Spectroscopic analysis and electrical characterization confirmed that the band gap and work function of Ta2Pt3S8 are 1.18 and 4.77 eV, respectively. Leveraging various electrode materials, we fabricated n-type FETs based on Ta2Pt3S8 and identified Cr as the optimal electrode, exhibiting a high mobility of 57 cm2 V-1 s-1. In addition, we analyzed the electron transport mechanism in n-type FETs by investigating Schottky barrier height, Schottky barrier tunneling width, and contact resistance. Furthermore, we successfully fabricated p-type operating Ta2Pt3S8 FETs using a molybdenum trioxide (MoO3) layer as a high work function contact electrode. Finally, we achieved Ta2Pt3S8 nanowire rectifying diodes by creating a p-n junction with asymmetric contact electrodes of Cr and MoO3, demonstrating an ideality factor of 1.06. These findings highlight the electronic properties of Ta2Pt3S8, positioning it as a promising 1D vdW material for future nanoelectronics and functional vdW-based device applications.

Delta-T Flicker Noise Demonstrated with Molecular Junctions.

Electronic flicker noise is recognized as the most abundant noise in electronic conductors, either as an unwanted contribution or as a source of information on electron transport mechanisms and material properties. This noise is typically observed when a voltage difference is applied across a conductor or current is flowing through it. Here, we identify an unknown type of electronic flicker noise that is found when a temperature difference is applied across a nanoscale conductor in the absence of a net charge current or voltage bias. The revealed delta-T flicker noise is demonstrated in molecular junctions and characterized using quantum transport theory. This noise is expected to arise in nanoscale electronic conductors subjected to unintentional temperature gradients, where it can be a performance-limiting factor. On the positive side, delta-T flicker noise can detect temperature differences across a large variety of nanoscale conductors, down to atomic-scale junctions with no special setup requirements.

Unraveling response mechanism of electron transport mechanism to uranium-exposure in Bacillus sp. X02

With the development of the uranium mining industry, the remediation of uranium pollution is an urgent environmental problem to be solved. Bioreduction is currently recognized as a U(VI) bioremediation method with good application prospects. However, inadequate reporting of uranium-reducing bacteria and low bioreduction efficiency are the main reasons limiting the application of the bioreduction method. In this paper, we isolated an efficient uranium-reducing bacterium, Bacillus sp. X02, explored the effect of U(VI) on bioreduction efficiency through electron transport mechanisms. The results showed that the maximum removal and reduction rate were 98.35 % and 62.43 %, respectively. Further studies revealed that the efficiency of extracellular electron transport of Bacillus sp. X02 was enhanced under U(VI) exposure. But uranium stress down-regulated the expression of F-type ATPase, Cytochrome c reductase ISP, Cytochrome c oxidase, and Cytochrome bd complex, inhibited the processes of complex III, complex IV, and ATP synthesis in the oxidative phosphorylation electron transport pathway, decreasing the electron transfer and U(VI) reduction capacity of Bacillus sp. X02 ultimately. This work proposed a new electron transfer pathway for U(VI) bioreduction and provided new insights into the effect of uranium on bioreduction efficiency.

The first-principles study on electronic transport mechanism in palladium decorated graphene for inert gas sensing

The first-principles study on electronic transport mechanism in palladium decorated graphene for inert gas sensing

Temperature dependent electron transport and interface state studies on Ni/n-Si/Al/Ag lateral Schottky junction

We investigate in this work,the electron transport characteristics across Ni/n-Si Schottky junctions from temperature dependent current–voltage (I-V-T) and capacitance–voltage (C-V-T) studies. Barrier height obtained from I–V measurements exhibited upsurge with increasing temperature, whereas, the ideality factor decreases with increasing temperature within the range of 300K–400K. To analyze electron transport mechanism, possibilities of Thermionic Field Emission and Generation-Recombination have been investigated over the temperature range, and, it has been observed that due to less characteristic energy at discussed temperature range; these effects have a minor contribution to electron transport. To account for the temperature-dependent properties and lateral barrier inhomogeneity, a double Gaussian spatial distribution of the potential barrier has been observed from conventional and modified Richardson plots. The density of Interface states at different energy levels from the conduction band has also been studied.

Fabrication of a novel Z-S-scheme photocatalytic fuel cell with the Z-scheme TiO2/GO/g-C3N4 photoanode and S-scheme BiOAc1−xBrx/BiOBr photocathode for TC degradation

The upsurge of interest in the emergence of photocatalytic fuel cell systems (PFC) presents an efficient and environmentally friendly approach to wastewater treatment. In this work, a Z-scheme coupled with an S-scheme heterojunction electrode was used in the PFC, utilizing TiO2/GO/g-C3N4 as the photoanode and BiOAc1–xBrx/BiOBr as the photocathode. We systematically align the band structures between the anode and cathode, which facilitates the electron transfer between the electrodes. Our attempt successfully demonstrates that collaborative power generation facilitates the high efficiency of tetracycline hydrochloride (TC) degradation at both electrodes. The photoanode achieved a 94.87 % degradation rate for TC, while the photocathode exhibited a 96.33 % degradation rate after 2 h, surpassing pristine BiOBr and BiOAc by factors of ∼5.3 and ∼3.8, respectively. Furthermore, this work proposed a mechanism for electron generation, transport, and pollutant degradation mechanism in the PFC. Intermediate substances generated during the degradation of TC were analyzed through high-performance liquid chromatography-mass spectrometry (HPLC-MS) and ultraviolet photoelectron spectroscopy (UPS), while the optimal degradation pathway was confirmed using density functional theory (DFT). The findings of this work establish the feasibility of efficiently degrading pollutants through PFC treatment, introducing a novel system where various heterojunctions in bipolar materials collaborate with photocatalysis to effectively generate electricity and enhance pollutant removal.