Electronic Materials Letters最新文献

Incorporation of chromium (Cr) nanoparticle onto LaFeO₃ (LFO) photocathode to improve optical and photocatalytic activities have been successfully demonstrated. The plain LFO photocathode was prepared by spin-spray gun deposition, following the Cr-incorporated nanoparticle onto the photocathode by spin coating method. It is observed that the photocathode with the optimal composition of 1.5 mmol Cr nanoparticle enhanced the crystal growth of orthorhombic crystal structure predominantly on (121) orientation with the formation of well-connected crystal grain architecture. The structure demonstrated strong optical absorption and a high current density of -60.52 µA cm^− 2 at -0.5 V (vs. Ag/AgCl) more than twice to the untreated LFO film which recorded a maximum photocurrent of -21.83 µA cm^− 2 at -0.5 V (vs. Ag/AgCl). This subsequently led to suppressed surface recombination, lower charge resistance and good stability in the strong alkaline electrolyte. The enhancement provided that incorporating a transition metal element with plain LFO would be applicable for producing efficient photosensitive devices, particularly for photoelectrochemical (PEC) water splitting applications.

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Graphene, a promising carbon nanomaterial, has garnered significant attention owing to its chemical stability, exceptional mechanical properties, and remarkable electrical conductivity and is being used in various electrical engineering applications ranging from solar cells to touch screens. The inherent mechanical strength and electric charge capacity of graphene enable efficient designs of diaphragms used in electrostatic loudspeakers, specifically within the high-frequency domain. This study incorporated single-layer and multi-layer graphene sheets, synthesized via chemical vapor deposition, as electrically charged diaphragms in electrostatic loudspeakers paired with an indium tin oxide film electrode to produce Coulomb force. Subsequently, the sound pressure levels of these distinct graphene- based electrostatic loudspeakers were determined through frequency response measurements. Based on our findings, we propose an optimal graphene film configuration for future electrostatic loudspeaker applications.

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Increasing energy requirement and over energy consumption and further upgrading of energy transfer and storage mechanisms are the critical problem. The supercapacitor is a good candidate for applications requiring high power delivery or uptake. Metal oxides can be effective electrode materials for energy storage devices due to their multiple oxidation states, high theoretical specific capacitance, wide potential window and eco-friendliness. In this connection, here report that electrodes made of notable nanosized transition metal oxides such as Ruthenium oxide (RuO₂), Nickel oxide (NiO) and Cobalt oxide (Co₃O₄) were prepared by simple hydrothermal route and the prepared samples were confirmed through structural, vibrational, morphological, and elemental composition analysis. The modified working electrodes were then examined for electrochemical behavior, including CV, GCD, and EIS studies, using a 1 M KOH electrolyte solution after successive coating of the working material on empty Ni foil. Among them, RuO₂ has high integral area, a low sweep rate and remarkable specific capacitance value of 447.1 Fg^-1 at 5 mVs^-1 in CV analysis. In addition, the GCD curve has good charge-discharge cyclic stability with a maximum specific capacitance of 412.1 Fg^-1 at 0.5 Ag^-1 compared to NiO and Co₃O₄. RuO₂ has long charge-discharge stability and only 6.8% loss in capacitive retention compared to the other systems, NiO (11.2%) and Co₃O₄ (9.3%), even after 10,000 cycles. We except that use of nanosized metal oxide electrodes to enhance electrochemical activity will lead to further improvement in the supercapacitors.

The development of efficient and durable catalysts for the hydrogen evolution reaction (HER) is essential for sustainable energy research. Cobalt sulfides (CoS_x) have attracted significant interest as prospective catalysts for the HER owing to their promising catalytic activity and high stability. In this study, CoS_x nanocrystals embedded in nitrogen-doped carbon frameworks (NC) are fabricated using a zeolite imidazole framework precursor via a two-step pyrolysis-sulfurization process, followed by combination with carbon black (CB) to create CoS_x-NC/CB as an efficient electrocatalyst for the HER. Interestingly, this catalyst displays a higher HER activity than that of the investigated materials, with an overpotential of 282 mV at a current density of 10 mA cm^− 2, along with a Tafel slope of 57.6 mV dec^− 1 in an acidic solution. This performance is attributed to the synergistic effect of CoS_x nanoparticles, nitrogen-doped carbon, and highly conductive CB, which improves the number of active sites, electron transfer, and electrochemical surface area. This outcome has significant potential for the development of economically viable catalysts for water splitting.

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Currently, transition metal tungstates are emerging as electroactive materials for supercapacitors due to their excellent electrical conductivity and electrochemical properties. Small amounts of transition metal ions doping can affect the physical and electrical properties of transition metal tungstates. In this study, Co ion-doped NiWO₄ amorphous composites (CNWO) were synthesized using a simple and effective hydrothermal method and utilized as the cathode material for supercapacitors. The structure and electrochemical properties of NiWO₄ and CNWO composites were investigated using various testing techniques. Specifically, when the cobalt ion doping amount is 10%, the corresponding CNWO-10 electrode material exhibits a specific capacitance of 804 F g⁻¹ at 1 A g⁻¹, and at a current density of 10 A g⁻¹, the capacitance retention rate reaches 66.7%, demonstrating good rate performance. Additionally, an asymmetric supercapacitor device was constructed using CNWO-10 and activated carbon (AC) as positive and negative materials, respectively. Which could cycle reversibly under a potential window of 2.1 V. The device demonstrates a maximum specific capacitance of 76.5 F g⁻¹ at 0.5 A g⁻¹, and a high energy density of 47 Wh kg⁻¹ at a power density of 527 W kg⁻¹. Furthermore, 96% capacitance cycling stability is maintained after 5500 cycles at a trapezoidal current density. Moreover, the electrical conductivities of NiWO₄ and CNWO-10 samples are 9.01 × 10^–8 S m⁻¹ and 8.93 × 10^–6 S m⁻¹, attributed to the Co ion-doping that can reduce the gap width of the forbidden band to enhance conductivity. These results suggest that CNWO composites can serve as promising high-capacity electrode materials for high-performance supercapacitors in alkaline electrolytes.

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In this paper, we studied the alcohol-sensing properties of CoMn₂O₄ nanoparticles for the first time. The CoMn₂O₄ nanoparticles were prepared via a simple microwave-assisted colloidal method using cobalt nitrate, manganese nitrate, dioctyl sulfosuccinate sodium salt, and ethylene glycol as a solvent. Various techniques were used to characterize the structural, morphological, and optical properties of CoMn₂O₄. The crystal structure of CoMn₂O₄ was found after calcination at a temperature of 400 °C. The Raman spectrum showed seven vibrational bands, while the optical absorption spectrum showed three bands, confirming the spinel CoMn₂O₄. Morphological analysis revealed that the porous microstructure of CoMn₂O₄ was composed of nanoparticles with a size distribution of 16 to 58 nm. Gas sensors were fabricated with the CoMn₂O₄ powders calcined at 400 °C using the brush-coating method, and experimental results showed that CoMn₂O₄ nanoparticles were more sensitive to n-butanol than isopropanol and ethanol at an operating temperature of 185 °C. The CoMn₂O₄ sensor showed a response of 6.6 at 50 ppm n-butanol with good stability, reproducibility, and repeatability. The present article provides a new sensing material that could be used as an n-butanol sensor with significant benefits for human health.

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Oxygen reduction reaction (ORR) is an important half-reaction in various energy devices such as fuel cells. Here, 2D dendritic Fe/N co-doped carbon-based nanosheet composites (L-Fe-CNT@NCS-900) were obtained by high-temperature calcination using ZIF-L generated in the aqueous phase as a precursor and Vitamin C as a modifier. It is found that the catalysts calcined at 900℃ possessed the large specific surface area and the pore size distribution graphs showed a narrow micropore size distribution centered at about 1.8 nm. Furthermore, the Fe-N-C species was detected, which further improved the ORR performance as an active center. Thus, the L-Fe-CNT@NCS-900 calcined at 900 °C achieved the best ORR performance with a half-wave potential (E_1/2) of 0.85 V, and the hydrogen peroxide yield is only about 4% during the ORR process. Meanwhile, L-Fe-CNT@NCS-900 exhibited outstanding methanol resistance. This work proposes a new strategy for constructing an efficient electrocatalysts for oxygen reduction reaction.

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Tl₃PbI₅ exhibits a bandgap energy suitable for absorbing visible and ultraviolet spectra along with a high absorption capability, rendering it a promising candidate for a broader range of solar energy applications. However, its applicability as a light absorber in solar cells is yet to be experimentally confirmed. In this study, we systemically investigate the synthesis process and the crystallographic and chemical properties of Tl₃PbI₅ nanocrystals. These results enable the optimization of Tl₃PbI₅ nanocrystals for use as a light absorber. In addition, a solid-state ligand exchange method employing methyl acetate (MeOAc) is introduced to construct a Tl₃PbI₅ absorption layer for photovoltaic applications. This method facilitates the preparation of multilayer thin films with precise thickness control. The optimally designed Tl₃PbI₅-based solar cell achieves a power conversion efficiency (PCE) of 0.20%. Furthermore, the device retains over 90% of its PCE after 2000 h at 25 °C and 60% relative humidity, indicating the potential of Tl₃PbI₅-based photovoltaics for reliable solar energy harvesting.

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Quasi-2D perovskite materials possess great potential in improving the stability of perovskite solar cells due to their superior chemical and structural stableness compared to 3D counterparts. Here, commonly-used 3D formamidinum lead iodide (FAPbI₃) perovskite is alloyed by addition of quaternary cation phenyltrimethylammonium (PTMA) up to 33% (n = 5), which forms quasi-2D perovskite phase that acts beneficial to charge transport and stability. Since the detailed structural analyses regarding this quaternary ammonium salt is still lacking, we attempt to provide how the presence of 2D perovskite affects the crystal structure based on x-ray diffraction techniques. It is shown that PTMA cations directs FAPbI₃ to have textured orientation and reduced strains. This led to enhanced extraction of photogenerated carriers and reduced defects, making it promising material for solar cell applications. The champion device remains stable under 60 °C or 1 sun for 700 h, demonstrating its potential for optoelectronic devices requiring long-term stability.

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Conducting polymers are proving to be useful for   construction of resistive switching devices. This work reports the fabrication of a resistive switching device using Magnetite-Polyaniline (Fe₃O₄-PANI) nanocomposite. The device showed good non-volatile memory properties and can mimic neuromorphic synaptic behavior. Initially, Fe₃O₄ nanoparticles were synthesized using the co-precipitation method and PANI by oxidative polymerization and their nanocomposites of different compositions were prepared and fully characterized. The 10% Fe₃O₄-PANI-based RS device outperforms all others in terms of I–V switching performance. Furthermore, the optimized device (10% Fe₃O₄-PANI) has tuneable I–V characteristics. The device demonstrated excellent analog switching at ± 1.5 V and digital switching at ± 2.5 V. The memristive behavior of the Ag/10% Fe₃O₄-PANI/FTO device was confirmed by the pinched hysteresis loop in the I–V curves at different voltages, as well as the double-valued charged-flux characteristics. The device has good cycle-to-cycle reliability for switching voltages and switching currents, as demonstrated by the Weibull distribution and other statistical measures. Moreover, the device can retain memory states up to 6 × 10³ s and shows a switching stability of 2 × 10⁴ cycles. The device also showed linear potentiation and depression characteristics and mimicked excitatory post-synaptic current (EPSC) and paired-pulse facilitation (PPF) index properties similar to its biological counterpart. According to the charge transport model fitting results, the Ohmic and Child’s square laws dominated in both analog and digital switching processes, and RS occurs due to the filamentary process.

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