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The trade-off between ultrahigh speed and low operating voltage is a major challenge in the continuous improvement of modern electronics. Although micro/nano plasma devices have demonstrated the potential of picosecond switching speed and high output power, surpassing traditional electronic devices, versatile methods for optimizing the operating voltage and switching speed are highly desired. Here, an optimization scheme based on the work function of the electrode materials is reported, which reduces the operating voltage and improves the switching speed. Compared with traditional methods, such as narrowing gaps or distorting electric fields, this approach offers advantages such as reducing production costs, enhancing consistency, and improving tunability. The experimental results show that using silver as a low-work-function electrode material can reduce the operating voltage by 55% to 180 V and increase the switching speed by 58% to 7.1 V ps−1 compared to platinum, which is equivalent to a 71% reduction in gap size. In addition, the underlying working mechanisms and inherent advantages of the approach are demonstrated, providing new insights for the ultrahigh switching speed and low-power application of micro/nano plasma devices, such as high-speed communication and ultrafast electronics. [ABSTRACT FROM AUTHOR]

A MoO3 film with the main phase of orthorhombic α-phase was deposited on a glass substrate by pulsed laser deposition. Metal–acid ionic liquid treatment caused the film to change from transparent to blue, while also reducing its bandgap and resistance values. These properties can be controlled by using different metals with lower work functions than MoO3, different acids, and varying treatment times. In this study, the film treated with Al-acid ionic liquid for 15 min showed the lowest bandgap of 2.61 eV and the smallest resistance of 9.48 × 103 Ω. This treatment resulted in a modulation of 0.59 eV in the bandgap and a more than 5 orders of magnitude increase in MoO3 conductivity. Both variable range hopping and activated behavior may be present throughout the entire temperature range in this study. The treating process causes an expansion of the crystal lattice, and the reduction of the Mo element. The manipulation of microstructures and properties may be attributed to the hydrogenation of the MoO3 thin films, driven by the difference in work function between the metal and oxide. This study expands the use of acids from inorganic acids to acidic ionic liquids, and enriches the method of metal–acid treatment. The concept of controllable hydrogen-doping through metal–acidic ionic liquid treatment has significant implications for the design of multifunctional materials in various applications. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWCNT) film/Si heterojunctions were obtained by depositing SWCNT films directly on a Si substrate by the floating catalyst chemical vapor deposition. The single-walled nature of the nanotubes was proven and confirmed by Raman and infrared spectroscopy, respectively. An additional ethanol post-growth treatment improved the properties of the heterojunctions by increasing densification of SWCNTs and decreasing their sheet resistance. Peaks positions of radial breathing mode obtained from the Raman mapping analysis demonstrated a random chirality (varying between armchair and zigzag) of tube structures and their very narrow diameter distribution, centered at ≈ 1.06 nm. This latter result was also confirmed by infrared spectroscopy. Properties of SWCNT/Si heterojunctions, such as ideality factor, Schottky barrier height, series resistance, SWCNT film work function and density of interface states are presented. To obtain the last two parameters by a self-consistent method, the intermediate nanolayer of silicon oxide between the SWCNT film and Si is considered. Impact of interface states and the native silicon oxide at the SWCNT/Si interface on the properties of heterojunctions is also discussed. Finally, such basic optoelectronic figures of merit as the responsivity, detectivity, and external quantum efficiency in the visible spectral range were determined and found to be comparable to the best reported for other SWCNT-based photodetectors. [ABSTRACT FROM AUTHOR]

In this work, several designs of lead-based and lead-free perovskite solar cells (PSCs) have been developed and investigated. For the proposed designs, CH3NH3PbI3 (lead-based), FAMASnGeI3, and CsGeI3 (lead-free) are used as absorber materials, Cu 2 O and NiO have been used as Hole Transport Layer (HTL) materials and TiO2 as Electron Transport Layer (ETL) materials. ETL materials, in general, have more concern with stability issues and HTL materials have more issues with efficiency improvements. The effect of changing thickness, doping density and defect density of the absorber layer, as well as HTL, defect density of absorber/HTL interface and work functions of front and back contacts on the performance of the proposed devices, are investigated. To enhance the device performance, optimization of the device parameters is performed. After optimization of different parameters, it is observed that the lead-based device structure TiO2/CH3NH3PbI3/NiO has a maximum efficiency of 29.94%. Even the corresponding lead-free device structure TiO2/CsGeI3/NiO exhibits a maximum efficiency of 29.19%. Additionally, this study delved into the influence of altering series and shunt resistances, as well as temperature on the operational characteristics of the lead-free optimized device. Such eco-friendly and cost-effective alternatives as lead-free perovskite cells can be very promising for future work. [ABSTRACT FROM AUTHOR]

Tribo-electrostatic separation is a dry method to separate fine particulates. This review discusses tribo-charging: generation, mechanism, control, characterization, and application in tribo-electrostatic separation with a particular focus on coal and mineral particles. Different types of tribo-electrostatic separators used for coal and minerals and factors influencing their separation are reviewed in this paper. Various pretreatment methods are also discussed. There are works reported on the tribo-electrostatic separation of coal and minerals after chemical pretreatments. However, the present published works on chemical pretreatments are preliminary, and many scopes exist to improve the process. More research is required to establish powder dry separation using a tribo-electrostatic method as an industrial process for separating coal and mineral systems. [ABSTRACT FROM AUTHOR]

[Display omitted] While great efforts have been made to improve the electrocatalytic activity of existing materials toward hydrogen evolution reaction (HER), it is also importance for searching new type of nonprecious HER catalysts to realize the practical hydrogen evolution. Herein, we firstly report nanocrystalline transition metal tetraborides (TMB 4 , TM=W and Mo) as an efficient HER electrocatalyst has been synthesized by a single-step solid-state reaction. The optimized nanocrystalline WB 4 exhibits an overpotential as low as 172 mV at 10 mA/cm2 and small Tafel slope of 63 mV/dec in 0.5 M H 2 SO 4. Moreover, the nanocrystalline WB 4 outperforms the commercial Pt/C at high current density region, confirming potential applications in industrially electrochemical water splitting. Theoretical study reveals that high intrinsic HER activity of WB 4 is originated from its large work function that contributes to the weak hydrogen-adsorption energy. Therefore, this work provides new insights for development of robust nanocrystalline electrocatalysts for efficient HER. [ABSTRACT FROM AUTHOR]

The present work deals with the Argon (Ar) Thermal plasma‐induced surface modification of Cu and its correlation with the electrical and field emission (FE) properties. Polycrystalline Cu targets were treated with Ar thermal plasma under atmospheric pressure at different treatment times ranging from 5 min to 30 min. XRD patterns revealed the absence of new phase in treated samples. However, significant variation in peak intensities and shifting is observed, which is explained on the basis of thermal plasma ions induced defect generation and annihilation processes. The electrical conductivity of processed Cu targets measured by four‐probe method ranges from 1.9 MS/m to 70 MS/m and is well correlated with the crystallite size variation. Surface modification induced work function alternations investigated by employing Scanning Kelvin Probe (SKP) technique are in the range of 4.69 eV 4.97 eV. The irradiated morphology explored by optical and scanning electron microscopy analyses revealed the formation of localized melt pools, grains, hillocks, spheroids, and sputtered patches, which are explainable on the basis of Coulomb's explosion, thermal spike model, plasma‐induced sputtering, and re‐deposition. FE properties of thermal plasma‐treated Cu are measured in diode configuration by measuring I‐V characteristics of target under ultra‐high vacuum condition. The improved FE parameters such as turn‐on field (Eo), field enhancement factor (β), and maximum current density (Jmax) come out to be in the range of 3–7.5 V/μm, 1715–3223, and 284–872 nA/cm2, respectively and their correlation with plasma‐induced surface structural, morphological and work function modifications is discussed. [ABSTRACT FROM AUTHOR]

In negative hydrogen ion sources in situ adsorption of Cs is typically used to generate low work function converter surfaces. The achievement of a temporally stable low work function coating is, however, challenging due to the hydrogen plasma interaction with the surface. Particularly in ion sources for neutral beam injection systems for fusion with pulse durations of minutes to hours temporal instabilities are a major issue and limit the source performance. To clarify the influence of the hydrogen plasma on the converter surface, investigations are performed at an experiment equipped with an absolute work function diagnostic based on the photoelectric effect. Caesiated surfaces are exposed to the full plasma impact by the generation of plasmas in front of the surface as well as to selected plasma species (H atoms, positive ions and VUV/UV photons) from an external plasma source to identify driving mechanisms that lead to surface changes. Depending on the exposure time and initial surface condition, the plasma strongly affects the surface in terms of work function and quantum efficiency (QE). For degraded Cs layers (work function ≥ 3 eV) a favorable increase in QE and reduction in work function can be achieved, while for Cs layers with an ultra-low work function of 1.2 - 1.3 eV the opposite is true. It is found that each plasma species can influence the Cs layers and that VUV photons lead to a work function increase of ultra-low work function layers. For sufficiently high VUV fluences a severe work function increase by 0.5 eV is given, highlighting the relevance of photochemical processes in the plasma-surface interaction and demonstrating that ultra-low work function layers are not stable in a hydrogen plasma environment. [ABSTRACT FROM AUTHOR]

Kelvin Probe Force Microscopy (KPFM) is a noncontact variant of atomic force microscopy (AFM) used to measure contact potential difference (CPD) between a probe tip and a sample surface. The sample's surface potential or work function can be extracted from the measured CPD. Since the surface potential relates to many surface functionalities, KPFM has diverse applications in advanced material and device research. For the quantitative nanoscale measurement of surface potential by KPFM, it is essential to establish the standard protocol using suitable reference materials (RM). This international pre-standardization research via the Versailles Project on Advanced Materials and Standards (VAMAS) aims to establish a practical protocol for quantitative surface potential measurements at the nanoscale. Based on the VAMAS project achievements, the final goal is to develop an international standard through the International Organization for Standardization (ISO). [ABSTRACT FROM AUTHOR]

The crystal phase of pseudocapacitive materials significantly influences charge storage kinetics and capacitance; yet, the underlying mechanisms remain poorly understood. This study focuses on tungsten oxide (WO3), a material exhibiting multiple crystal phases with potential for energy storage. Despite extensive research on WO3, the impact of different crystal structures on charge storage properties remains largely unexplored. Here, the successful synthesis and electrochemical characterization of tetragonal WO3 are reported. This investigation demonstrates that tetragonal WO3 exhibits superior energy storage capabilities compared to other WO3 polymorphs. According to in situ Raman spectroscopy and ultraviolet photoelectron spectroscopy combined with in‐depth electrochemical analyses, this enhancement is attributed to a unique charge storage mechanism and an expanded potential window facilitated by an engineered electrode work function. This study highlights the critical role of the crystal phase in optimizing the performance of pseudocapacitive materials and provides valuable insights for the development of next‐generation energy storage devices. [ABSTRACT FROM AUTHOR]