Electron Conductivity Research Articles

Evolving non-aggregated ZIF-8 nanoparticles into hierarchically porous hollow carbon nanofibers for high-performance flexible zinc-ion hybrid supercapacitor

Zinc-ion hybrid supercapacitors are garnering widespread interest in wearable energy storage devices due to their high power density, intrinsic safety and cost-effectiveness. However, the primary obstacle to their progress lies in the scarcity of cathode materials that concurrently demonstrate excellent flexibility and high energy density. Herein, we deliberately design a coaxial electrospinning ZIF-8 derived hollow carbon nanofiber film electrode (C-PAN(ZIF-8)@PVP) to achieve high-performance flexible ZHSCs. The distinctive configuration of C-PAN(ZIF-8)@PVP electrode comprises a shell of homogeneously distributed ZIF-8 derived porous carbon nanoparticles, which are bound together by N-doped carbon fibers derived from polyacrylonitrile (PAN), and a channel through the fiber created by the decomposition of polyvinylpyrrolidone (PVP). This unique architecture coupled with N, O co-doping bestows ample electrolyte infiltration, complete exposure of active sites, and a rapid pathway for electron conduction, resulting in facilitated ion diffusion kinetics, abundant active sites and enhanced electronic conductivity of the C-PAN(ZIF-8)@PVP electrode. As a result, the assembled ZHSC delivers a high reversible capacity of 116 mAh g−1 at 0.1 A g−1 and remarkable capacity retention of 100% over 4000 cycles at 5 A g−1. Moreover, it exhibits exceptional mechanical flexibility, capable of delivering stable output under arbitrary deformation. The intricate structural design strategy offers valuable insights for the development of high-performance electrode materials.

Unveiling the temperature-dependent thermoelectric properties of the undoped and Na-doped monolayer SnSe allotropes: a comparative study

Motivated by the excellent thermoelectric (TE) performance of bulk SnSe, extensive attention has been drawn to the TE properties of the monolayer SnSe. To uncover the fundamental mechanism of manipulating the TE performance of the SnSe monolayer, we perform a systematic study on the TE properties of five monolayer SnSe allotropes such as α-, β-, γ-, δ-, and ε-SnSe based on the density functional theory and the non-equilibrium Green’s functions. By comparing the TE properties of the Na-doped SnSe allotropes with the undoped ones, the influences of the Na doping and the temperature on the TE properties are deeply investigated. It is shown that the figure of merit ZT will increase as the temperature increases, which is the same for almost all the Na-doped and undoped cases. The Na doping can enhance or suppress the ZT in different SnSe allotropes at different temperatures, implying the presence of the anomalous suppression of the ZT. The Na doping induced ZT suppression may be caused basically by the sharp decrease of the power factor and the weak decrease of the electronic thermal conductance, rather than by the decrease of the phononic thermal conductance. We hope this work will be able to enrich the understanding of the manipulation of TE properties by means of dimensions, structurization, doping, and temperature.

In Situ Design of a Nanostructured Interface between NiMo and CuO Derived from Metal-Organic Framework for Enhanced Hydrogen Evolution in Alkaline Solutions.

Hydrogen shows great promise as a carbon-neutral energy carrier that can significantly mitigate global energy challenges, offering a sustainable solution. Exploring catalysts that are highly efficient, cost-effective, and stable for the hydrogen evolution reaction (HER) holds crucial importance. For this, metal-organic framework (MOF) materials have demonstrated extensive applicability as either a heterogeneous catalyst or catalyst precursor. Herein, a nanostructured interface between NiMo/CuO@C derived from Cu-MOF was designed and developed on nickel foam (NF) as a competent HER electrocatalyst in alkaline media. The catalyst exhibited a low overpotential of 85 mV at 10 mA cm-2 that rivals that of Pt/C (83 mV @ 10 mA cm-2). Moreover, the catalyst's durability was measured through chronopotentiometry at a constant current density of -30, -100, and -200 mA cm-2 for 50 h each in 1.0 M KOH. Such enhanced electrocatalytic performance could be ascribed to the presence of highly conductive C and Cu species, the facilitated electron transfer between the components because of the nanostructured interface, and abundant active sites as a result of multiple oxidation states. The existence of an ionized oxygen vacancy (Ov) signal was confirmed in all heat-treated samples through electron paramagnetic resonance (EPR) analysis. This revelation sheds light on the entrapment of electrons in various environments, primarily associated with the underlying defect structures, particularly vacancies. These trapped electrons play a crucial role in augmenting electron conductivity, thereby contributing to an elevated HER performance.

Bottom-up multi-interface modification boosts the performance of carbon-based HTL-free all-inorganic CsPbI2Br perovskite solar cells

The inferior interface quality between CsPbI2Br perovskite and the electron transport layer (ETL) as well as carbon electrode limits the stability and power conversion efficiency (PCE) of hole transport layer (HTL) free carbon-based all-inorganic CsPbI2Br perovskite solar cells (C-IPSCs). Herein, perfluoropropionic acid (PFPA) is designed as a bottom-up multiple surface defect passivator that can simultaneously passivate perovskite/TiO2 interface and perovskite/carbon electrode interface. The comprehensive experiments demonstrate that PFPA can not only optimize the electron mobility, conductivity, and band structure of the TiO2 ETL through passivating oxygen vacancies (VO), but also diffuse to the upper surface of perovskite film through grain boundaries to passivate the surface lead defects, thereby facilitating the gradient alignment of the perovskite surface energy levels with the carbon electrode. At the same time, PFPA can effectively release the tensile stress at the interface of perovskite and reduce the delocalization state of the band tail caused by lattice distortion, so as to prepare high-quality perovskite films. As a result of the above interaction, the PCE of HTL-free CsPbI2Br C-IPSCs after PFPA modification is increased from 12.24% (control device) to 14.15%. In addition, the modified unencapsulated devices show superior long-term stability and thermal stability.

Oxygen-defected WO3-OVs@Bi2MoO6 S-scheme micro flowers heterojunctions with promoted photocatalytic degradation of tetracycline

The synergy between surface oxygen vacancies (OVs) and heterojunction engineering holds promising potential for substantially enhancing photoelectric conversion efficiency through the optimization of photogenerated charge carrier transport. Herein, novel WO3-OVs@Bi2MoO6 S-scheme heterostructures are synthesized via a simple route for degradation of tetracycline hydrochloride (TC) using visible light. The S-scheme charge transfer mode markedly enhances the spatial separation and preservation of high-energy electrons/holes on Bi2MoO6 (reduction) and WO3-OVs (oxidation), consequently providing WO3-OVs@Bi2MoO6 photocatalysts with an improved redox capability. The optimal WO3-OVs@Bi2MoO6 heterojunction demonstrates enhanced visible-light-driven photocatalytic degradation of tetracycline, exhibiting 4.86-fold and 4.17-fold higher efficiency compared to WO3-OVs and Bi2MoO6, respectively, with superior stability and reusability. Confirmation of the existence of the S-scheme charge transfer mechanism and oxygen vacancies (OVs) is achieved through a combination of density functional theory (DFT) calculations and in-situ X-ray photoelectron spectroscopy (XPS), substantiating the enhancement of charge separation and redox capability. Specifically, the presence of oxygen vacancies (OVs) on the surface of WO3 nanofibers results in a reduction of the band gap energy due to the defect levels, consequently promoting increased electron conduction. Furthermore, the abundance of oxygen vacancies (OVs) expands the photo response range and facilitates charge transfer at the interface. This research opens new avenues for the successful photocatalytic degradation of tetracycline (TC) by integrating hierarchical S-scheme heterojunction design and cutting-edge defect engineering in photocatalytic heterojunctions.

Highly sensitive detection of multiple antiviral drugs using graphitized hydroxylated multi-walled carbon nanotubes/ionic liquids-based electrochemical sensors

Global outbreaks and the spread of viral diseases in the recent years have led to a rapid increase in the usage of antiviral drugs (ATVs), the residues and metabolites of which are discharged into the natural environment, posing a serious threat to human health. There is an urgent need to develop sensitive and rapid detection tools for multiple ATVs. In this study, we developed a highly sensitive electrochemical sensor comprising a glassy carbon electrode (GCE) modified with graphitized hydroxylated multi-walled carbon nanotubes (G-MWCNT-OH) and 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6, IL) for the detection of six ATVs including famciclovir (FCV), remdesivir (REM), favipiravir (FAV), hydroxychloroquine sulfate (HCQ), cepharanthine (CEP) and molnupiravir (MOL). The morphology and structure of the G-MWCNT-OH/IL nanocomposites were characterized comprehensively, and the electroactive surface area and electron conductivity of G-MWCNT-OH/IL/GCE were determined using cyclic voltammetry and electrochemical impedance spectroscopy. The thermodynamic stability and non-covalent interactions between the G-MWCNT-OH and IL were evaluated through quantum chemical simulation calculations, and the mechanism of ATV detection using the G-MWCNT-OH/IL/GCE was thoroughly examined. The detection conditions were optimized to improve the sensitivity and stability of electrochemical sensors. Under the optimal experimental conditions, the G-MWCNT-OH/IL/GCE exhibited excellent electrocatalytic performance and detected the ATVs over a wide concentration range (0.01–120 μM). The limit of detections (LODs) were 42.3 nM, 55.4 nM, 21.9 nM, 15.6 nM, 10.6 nM, and 3.2 nM for FCV, REM, FAV, HCQ, CEP, and MOL, respectively. G-MWCNT-OH/IL/GCE was also highly stable and selective to the ATVs in the presence of multiple interfering analytes. This sensor exhibited great potential for enabling the quantitative detection of multiple ATVs in actual water environment.

Effect of Microstructure on the Precipitation of β-Mg2Si during Cooling after Homogenisation of Al-Mg-Si Alloys

For Al-Mg-Si alloys, cooling after homogenisation is a crucial step because the precipitation of the equilibrium β-Mg2Si phase determines the processing capabilities in subsequent steps, as well as the subsequent precipitation age hardening potential, and thus, the final properties. It is therefore important to understand how microstructural variations affect the transformation of β-Mg2Si during cooling after homogenisation. In the present work, alloys with similar effective solute contents of Mg and Si, but with different microstructures and a different amount of primary Al-Fe-Si phases, were produced. Characterisation of the precipitation reaction was performed using interrupted quench experiments with cooling rates of 1–6 K/min, monitored by light optical microscopy (LOM), scanning electron microscopy (SEM) and conductivity measurements. Precipitation kinetics for β-Mg2Si was found to increase in microstructures with shorter secondary dendrite arm spacing (DAS). However, despite measuring both a higher density and volume fraction of the primary phases, no effect on the phase transformation from an increased iron content was found in terms of precipitation kinetics or particle count statistics. Furthermore, comparisons with iron-free high-purity-based alloys revealed that the precipitation reaction for β-Mg2Si was identical in the two different microstructures both in terms of onset temperature and overall kinetics. The present results show that nucleation of β-Mg2Si is not dependent on the larger constituent phases and indicates that overall transformation kinetics is governed by bulk diffusion rates.

Inorganic Fe-O and Fe-S oxidoreductases: paradigms for prebiotic chemistry and the evolution of enzymatic activity in biology.

Oxidoreductases play crucial roles in electron transfer during biological redox reactions. These reactions are not exclusive to protein-based biocatalysts; nano-size (<100nm), fine-grained inorganic colloids, such as iron oxides and sulfides, also participate. These nanocolloids exhibit intrinsic redox activity and possess direct electron transfer capacities comparable to their biological counterparts. The unique metal ion architecture of these nanocolloids, including electron configurations, coordination environment, electron conductivity, and the ability to promote spontaneous electron hopping, contributes to their transfer capabilities. Nano-size inorganic colloids are believed to be among the earliest 'oxidoreductases' to have 'evolved' on early Earth, playing critical roles in biological systems. Representing a distinct type of biocatalysts alongside metalloproteins, these nanoparticles offer an early alternative to protein-based oxidoreductase activity. While the roles of inorganic nano-sized catalysts in current Earth ecosystems are intuitively significant, they remain poorly understood and underestimated. Their contribution to chemical reactions and biogeochemical cycles likely helped shape and maintain the balance of our planet's ecosystems. However, their potential applications in biomedical, agricultural, and environmental protection sectors have not been fully explored or exploited. This review examines the structure, properties, and mechanisms of such catalysts from a material's evolutionary standpoint, aiming to raise awareness of their potential to provide innovative solutions to some of Earth's sustainability challenges.

Thermoelectric properties of Marcus molecular junctions

In the present work we theoretically analyze thermoelectric transport in single-molecule junctions (SMJ) characterized by strong interactions between electrons on the molecular linkers and phonons in their nuclear environments where electron hopping between the electrodes and the molecular bridge states predominates in the steady state electron transport. The analysis is based on the modified Marcus theory accounting for the lifetime broadening of the bridge’s energy levels. We show that the reorganization processes in the environment accompanying electron transport may significantly affect SMJ thermoelectric properties both within and beyond linear transport regime. Specifically, we study the effect of environmental phonons on the electron conductance, the thermopower and charge current induced by the temperature gradient applied across the system.

The tellurium-induced CoSe polyhedral porous nano-structured materials as high-performance cathodes for rechargeable magnesium batteries

Rechargeable magnesium batteries (RMBs) are cost-effective and dendrite-free, making them desirable for large-scale applications. Nevertheless, the exploration of high-performance cathodes still remains a great challenge in magnesium battery research. Herein, the CoSe porous polyhedra induced by Te heteroatoms (CoSe/Te) are successfully prepared by two-step metal-organic framework (MOF)-template assisted method and investigated as high-efficiency cathodes for rechargeable MIBs. In this regard, the affluent porous structure can facilitate the transport of Mg2+ ions while the introduction of Te heteroatoms can reduce the conversion reaction barrier, boost the kinetics and redox reversibility and excite the electron conduction to build active nanostructured domains for highly reversible Mg storage reactions. As a consequence, the CoSe/Te maintains the high specific capacity of 150.6 mAh g−1 after 600 cycles at 200 mA g−1, with a superior capacity retention rate of 75.3%. Moreover, the specific capacity of such electrode materials changed from 260 mAh g−1 to 41 mAh g−1 when the current density increased from 100 mA g−1 to 2000 mA g−1, and gradually recovered to 256.5 mAh g−1 when the current density returned to 100 mAh g−1, exhibiting a better rate performance. This work highlights how micro-nanostructures can favor magnesium storage reaction reversibility and cyclability and also provide insights into rational electrode design for storing magnesium cations in future studies.

Determination of the Seebeck Coefficient and Other Thermoelectric Parametersusing Specific Resistivity and Concentration of Charge Carriers of N-Si0.96Ge0.04 Alloy Irradiated by 60Co γ-photons

The thermoelectric alloy N-Si0.96Ge0.04-P irradiated by 60Co gamma-photons is been studied. The temperature dependences of the Seebeck coefficient, power and electronic quality factors, as well as the universal electrical conductivity and effective masses of electrons in the interval (250400)°C are calculated. All these dependences are different from the results previously obtained for SixGe1-x with other compositions (except for effective mass). This should be associated with a significant difference in specific resistivities and concentrations of charge carriers.

Entropy-Driven Enhancement of the Conductivity and Phase Purity of Na4Fe3(PO4)2P2O7 as the Superior Cathode in Sodium-Ion Batteries.

Na4Fe3(PO4)2(P2O7) (NFPP) is regarded as a promising cathode material for sodium-ion batteries (SIBs) owing to its low cost, easy manufacture, environmental purity, high structural stability, unique three-dimensional Na-ion diffusion channels, and appropriate working voltage. However, for NFPP, the low conductivity of electrons and ions limits their capacity and power density. The generation of NaFeP2O7 and NaFePO4 inhibits the diffusion of sodium ions and reduces reversible capacity and rate performance during the manufacturing process in synthesis methods. Herein, we report an entropy-driven approach to enhance the electronic conductivity and, concurrently, phase purity of NFPP as the superior cathode in sodium-ion batteries. This approach was realized via Ti ions substituting different ratios of Fe-occupied sites in the NFPP lattice (denoted as NTFPP-X, T is the Ti in the lattice, X is the ratio of Ti-substitution) with the configurational entropic increment of the lattice structures from 0.68 R to 0.79 R. Specifically, 5% Ti-substituted lattice (NTFPP-0.05) inducing entropic augmentation not only improves the electronic conductivity from 7.1 × 10-2 S/m to 8.6 × 10-2 S/m but also generates the pure-phase of NFPP (suppressing the impure phases of the NaFeP2O7 and NaFePO4) of the lattice structure, which is validated by a series of characterizations, including powder X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). Benefiting from the Ti replacement in the lattice, the optimal NTFPP-0.05 composite shows a high first discharge capacity (118.5 mAh g-1 at 0.1 C), superior rate performance (70.5 mAh g-1 at 10 C), and excellent long cycling life (1200 cycles at 10 C with capacity retention of 86.9%). This research proposes a new entropy-driven approach to improve the electrochemical performance of NFPP and reports a low-cost, ultrastable, and high-rate cathode material of NTFPP-0.05 for SIBs.

Nonlinear Landau Fan Diagram for Graphene Electrons Exposed to a Moiré Potential.

Due to Landau quantization, the conductance of two-dimensional electrons exposed to a perpendicular magnetic field exhibits oscillations that generate a fan of linear trajectories when plotted in the parameter space spanned by density and field. This fan looks identical, irrespective of the dispersion and field dependence of the Landau level energy. This is no surprise because the position of conductance minima depends solely on the level degeneracy that is linear in flux. The fractal energy spectrum that emerges within each Landau band when electrons are also exposed to a two-dimensional superlattice potential produces numerous additional oscillations, but they also create just linear fans for identical reasons. Here, we report conductance oscillations of graphene electrons exposed to a moiré potential that defy this general rule and form nonlinear trajectories in the density-field plane. We attribute this anomalous behavior to the simultaneous occupation of multiple minibands and magnetic breakdown-induced open orbits.

On the Capacitive-to-Resistive Humidity Response of Polyelectrolyte-Gated Metal Oxide Transistors

The electrolyte gating of transistors, which directly couples ion transport with electron conduction, is particularly interesting in the field of bio and chemical sensing. When a humidity-sensitive polyelectrolyte is used as the gate dielectric, the resulting ionotronic device becomes a humidity-sensitive transistor providing potential advantages in signal amplification and circuit integration. In this work, a humidity-sensitive polyelectrolyte-gated metal oxide transistor is reported by implementing the capacitive-to-resistive-based sensing mechanism. Due to the correlation between drain current and gate capacitance, the measurement of capacitance or impedance for humidity sensors is converted into the measurement of resistance. Initial sensing studies in the quasi-static DC sensing mode resulted in a limited sensing response. A pulsed sensing mode was proposed to considerably enhance the sensing response I D,80%RH /I D,20%RH to 861. The response in the specific RH range was also found to be tunable with the applied sensing signal. The underlying mechanism is elucidated with frequency-dependent capacitance and impedance analysis of the gate electrolyte using corresponding equivalent circuit model.

Improvement in the Performance of Composite Cathode via Solid Electrolyte for High Electrochemical Performance of Li–S Battery

AbstractCommercialization of Li–S in present scenario is obstructed by poor performance of cathode and its compatibility with electrolyte used. Here in this work, in order to improve the electrochemical performance all solid state Li–S battery, solid electrolyte (SE) formed by composition of lithium sulfide (Li2S) and phosphorus pentasulfide (P2S5) combinedly called LPS is used. The modified carbon in the form of graphene oxide (GO) and reduced graphene oxide (rGO) as additive is used to provide better electron conduction pathway. High conductivity of the order 10−4 S cm−1 of prepared LPS overcomes the major drawback of insulating nature of sulfur. The coin cells are fabricated by using above mentioned material as a cathode material, LPS as SE, and lithium foil as anode. The prepared nanocomposites are characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) to study structural and morphological properties. Energy dispersive X‐ray spectroscopy (EDS) images of the cathode surface confirms the uniform spreading of material. The electrochemical performance of coin cell is studied by Galvanostatic charge‐discharge plot at 0.1 C to check the compatibility of composite and electrolyte prepared. The cells having additive material GO and rGO with host sulfur show better results as compared to the cell having pristine sulfur.

Ti3C2Tx MXene/carbon composites for advanced supercapacitors: Synthesis, progress, and perspectives

AbstractMXenes are a family of two‐dimensional (2D) layered transition metal carbides/nitrides that show promising potential for energy storage applications due to their high‐specific surface areas, excellent electron conductivity, good hydrophilicity, and tunable terminations. Among various types of MXenes, Ti3C2Tx is the most widely studied for use in capacitive energy storage applications, especially in supercapacitors (SCs). However, the stacking and oxidation of MXene sheets inevitably lead to a significant loss of electrochemically active sites. To overcome such challenges, carbon materials are frequently incorporated into MXenes to enhance their electrochemical properties. This review introduces the common strategies used for synthesizing Ti3C2Tx, followed by a comprehensive overview of recent developments in Ti3C2Tx/carbon composites as electrode materials for SCs. Ti3C2Tx/carbon composites are categorized based on the dimensions of carbons, including 0D carbon dots, 1D carbon nanotubes and fibers, 2D graphene, and 3D carbon materials (activated carbon, polymer‐derived carbon, etc.). Finally, this review also provides a perspective on developing novel MXenes/carbon composites as electrodes for application in SCs.

Impurity reduction in lightly doped n-type gallium nitride layer grown via halogen-free vapor-phase epitaxy

The development of gallium nitride (GaN) vertical-type metal-oxide-semiconductor field-effect transistors and p–i–n diode devices has gathered increasing attention. These devices require an n-type drift layer with a low doping level of 1016 cm−3 or less, minimized point defects inhibiting electron conduction, and a layer approximately 10 μm thick. Therefore, a practical method with a growth rate of at least several tens of μm/h and impurity concentrations of less than 1015 cm−3, except for that of dopants, is necessary. Halogen-free vapor-phase epitaxy (HF-VPE) has a high growth rate suitable for fabricating thick drift layers and utilizes a simple reaction between Ga vapor and ammonia gas (without a corrosive halogen gas), resulting in lower impurity levels. Herein, we eliminated the quartz content from the high-temperature zone to reduce the excess unintentional Si doping and identified that the nitrile gloves used for the growth preparation are other impurity contamination sources. We obtained a lightly n-type ([Si]=∼1016 cm−3) GaN layer, in which C, O, B, Fe, Mg, Al, Ca, Cr, Zn, Ni, Mn, and Ti impurity contents were below the detection limits of secondary ion mass spectrometry. Deep-level transient spectroscopy revealed that electron traps at EC − 0.26 and at EC − 0.59 eV were 2.7 × 1013 and 5.2 × 1014 cm−3, respectively. Moreover, the Hall effect analysis showed the acceptor-type defect-compensating donor content as approximately 2.7 × 1015 cm−3, resulting in a high electron mobility of HF-VPE GaN in the 30–710 K temperature range. Furthermore, we identified the Ca impurity as a deep acceptor, another killer defect leading to mobility collapse.

Electrochemical Ionic Synapses with Mg2+as the Working Ion

AbstractDynamic doping by electrochemical ion intercalation is a promising mechanism for modulating electronic conductivity, allowing for energy‐efficient, brain‐inspired computing hardware. While proton‐based devices have achieved success in terms of speed and efficiency, the volatility and environmental pervasiveness of hydrogen (H) might limit the robustness of devices during fabrication, as well as the long‐term retention of devices after programming. This motivates the search for alternative working ions. In this work, a proof‐of‐concept is demonstrated for electrochemical ionic synapses (EIS) based on intercalation of Mg2+ions. The reported device has a symmetric design, with MgxWO3used as both the gate and channel material. Increasing the Mg fraction,x, in WO3increases the electronic conductance in a continuum over a large range (80 nS − 2 mS). Ex situ characterization of the channel confirms that modulation of channel conductance is due to Mg2+intercalation. Unlike H‐EIS which rapidly loses programmed conductance states over a few seconds when exposed to air, Mg‐EIS can be operated and has good retention in air, with no sign of degradation after 1 h. Mg2+as a working ion with WO3as the channel is a promising material system for EIS with long‐term retention and low energy consumption.

STUDY OF VOLTAGE AND ELECTRIC CURRENT GENERATED FROM CU-ZN ELECTRODES IN A MEDIUM OF SAWDUST AND COAL STOCKPILE WASTEWATER.

Industrialization has positive effects on the economy, but on the other hand, it also adversely impacts the environment and energy needs. This phenomenon needs to be solved in an integrated way, including using wastewater from coal stocks and sawdust as electrolyte media to generate electrical energy. This study aims to analyze the voltage and electric current generated by electrode pairs consisting of copper (Cu) and zinc (Zn) immersed in different sawdust media denoted as M1 (2 grams), M2 (4 grams), M3 (6 grams), and M4 (8 grams), dissolved in 100 milliliters of coal stockpile wastewater. Additionally, the study explores the effects of varying the distance between the Cu-Zn electrodes at 1, 2, and 3 cm. The results showed that the highest voltage generated from the combination of coal stockpile wastewater and sawdust was highest in M3 (6 grams of sawdust + 100 ml of coal stockpile wastewater at a distance of 1 cm at 0.736 volts. The highest electrical current generated by the Cu-Zn electrode in the M3 media combination was 0.221 mA. It is due to coal stockpile wastewater in M3 sawdust powder, which contains ions that enhance electron conduction compared to M4.

Magnetron Sputtering as a Versatile Tool for Precise Synthesis of Hybrid Iron Oxide–Graphite Nanomaterial for Electrochemical Applications

Iron oxide nanomaterials are promising candidates for various electrochemical applications. However, under operating conditions high electric resistance is still limiting performance and lifetime. By incorporating the electronically conductive carbon into a nanohybrid, performance may be increased and degeneration due to delamination may be prevented, eliminating major drawbacks. For future applications, performance is an important key, but also cost-effective manufacturing suitable for scale-up must be developed. A possible approach that shows good potential for up-scale is magnetron sputtering. In this study, a systematic investigation of iron oxides produced by RF magnetron sputtering was carried out, with a focus on establishing correlations between process parameters and resulting structural properties. It was observed that increasing the process pressure was favourable with regard to porosity. Over the entire pressure range investigated, the product consisted of low-crystalline Fe3O4, as well as Fe2O3 as a minor phase. During sputtering, a high degree of graphitisation of carbon was achieved, allowing for sufficient electronic conductivity. By means of a new alternating magnetron sputtering process, highly homogeneous salt-and-pepper-type arrangements of both nanodomains, iron oxide and carbon were achieved. This nano-containment of the redox-active species in a highly conductive carbon domain improves the material’s overall conductivity, while simultaneously increasing the electrochemical stability by 44%, as confirmed by cyclic voltammetry.