Search

The rate capability of the AVNF//Al2O3@Zn was 108 mAh g-1 even at 20 A g-1, by employing the sonochemical method, which is the fast and efficient synthesis. The Zn anode were coated by Al2O3 of 9.9 nm, and therefore, the initial capacity is maintained to 94 % after 5,000 cycles even at 10 A g-1.

The triboelectric performance of the SMC-PDMS-based TENG was improved by enhancing the capacitance of the device owing to the synergistic effect of the superior dispersion degree and permittivity of the SMCs.

The design of atomically dispersed single atom catalysts (SACs) must consider high metal-atom loading amount, effective confinement, and strong interactions with matrix, which can maximize their catalytic performance. Here reported is a promising method to synthesize SACs on highly conductive multiwall carbon nanotube (MWCNT) supports using pulsed laser confinement (PLC) process in liquid. Atomic cobalt (Co) and phosphorus (P) with a high loading density are homogeneously incorporated on the outer wall of the MWCNT (Co-P SAC MWCNT). Density functional theory (DFT) calculations in combination with systematic control experiments found that the incorporated Co and P adatoms act as an adsorption energy optimizer and a charge transfer promoter, respectively. Hence, favorable kinetics and thermodynamics in Co-P SAC MWCNT can be simultaneously achieved for water oxidation resulting in a superior catalytic performance than the benchmark RuO2 catalyst. Crucially, total processing time for assembling Co-P SAC MWCNT via PLC process is less than 60 min, shedding light on the promising practical applications of our SAC design strategy.

Recently, aqueous Zn-ion rechargeable batteries have drawn increasing research attention as an alternative energy storage system relative to the current Li-ion batteries due to their intrinsic properties of high safety, low cost, and high theoretical volumetric capacity. Nevertheless, unwanted dendrite growth on the Zn anode and unstable cathode materials restrict their practical application. In this study, a unique 2D MoS2 coating on a Zn anode using an electrochemical deposition method has been developed for preventing dendrite growth and intricate side reactions. The coated MoS2 layer is a vertically oriented structure that makes the flow of Zn ions easy with a uniform electric field distribution on the anode, resulting in a uniform stripping and plating of Zn2+. In addition, the MoS2 coating enhances anodic diffusion of Zn ions and reduces the series resistance as confirmed by EIS analysis and therefore improves the overall battery performance. The full cell assembled with the MoS2-Zn anode and MnO2 cathode exhibits an excellent reversible specific capacity of 638 mAh/g at 0.1 A/g and stable cycle performance over 2000 cycles with no dendrite formation at the Zn electrode. The presented MoS2 coating on Zn is a facile, scalable, and promising technology for practical Zn-ion batteries with a long life cycle and high safety.

Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core-shell CoFeS

In this study, microstructures of weldment produced using carbon steel A516 grade 60 were analysed via a deep learning approach to measure the fraction of acicular ferrite which considerably influe...

Metal–fluoride possesses a high potential as new high-performance water oxidation catalysts due to a highly polarized electronic configuration. However, low conductivity, related to high iconicity ...

It has recently been demonstrated that the OER activity of transition metal sulfides (TMSs) could be enhanced by the introduction of a thin amorphous layer on a pristine surface. We report here a novel strategy to enhance the OER by developing cobalt nickel sulfide (CoxNi1−xS2, CNS) with a high density of crystalline and amorphous phase boundaries. Electrochemical activation (ECA) can partially amorphize hollow CNS nanoparticles derived from surface-selective sulfidation. The ECA-treated CNS (ECA-CNS) electrocatalyst, which is comprised of CNS nanodots separated by thin amorphous layers, shows high densities of crystalline and amorphous phase boundaries. This catalyst shows superior OER catalytic performance with a current density of 10 mA cm−2 at a small overpotential of 290 mV, a low Tafel slope of 46 mV dec−1, a high mass activity of 217 A g−1, a high turnover frequency of 0.21 s−1 at an overpotential of 340 mV, and excellent stability in alkaline media.

The development of cost-effective and high-performance electrocatalysts for water oxidation has attracted intense research interest. It was reported recently that the interface between the amorphous and crystalline phases plays a significant role in the electrocatalytic activity of transition metal compounds. It was reckoned therefore that an increase in the density of the crystalline–amorphous phase boundary would enhance the electrochemical water oxidation on the catalyst. In this work we develop a new and facile strategy for inducing high density crystalline–amorphous phase boundaries via selective fluorination surface doping. This resulted in excellent characteristics of the engineered material for electrochemical water splitting. An initial computational simulation is carried out to design the crystalline–amorphous phase boundary material and an experimental verification follows for demonstration and optimization of the impact of surface doping. We conclude that the engineering of the interface using this facile and cost-effective strategy maximizes the crystalline and amorphous phases of metal–metalloids, which can be used to fabricate low-cost and efficient electrocatalysts for water oxidation.

In this work, we prepared spinel-type NiCo2O4 (NCO) nanopowders as a low-cost and sensitive electrochemical sensor for nonenzymatic glucose detection. A facile and simple chemical bath method to synthesize the NCO nanopowders is demonstrated. The effect of pH and annealing temperature on the formation mechanism of NCO nanoparticles was systematically investigated. Our studies show that different pHs of the precursor solution during synthesis result in different intermediate phases and relating chemical reactions for the formation of NCO nanoparticles. Different morphologies of the NCO depending on pHs are also discussed based on the mechanism of growth. Electrochemical performance of the prepared NCO was characterized towards glucose, which reveals that sensitivity and selectivity of the NCO are significantly related with the final microstructure combined with constituent species with multiple oxidation states in the spinel structure.

Recently, aqueous Zn-ion rechargeable batteries have drawn increasing research attention as an alternative energy storage system relative to the current Li-ion batteries due to their intrinsic properties of high safety, low cost, and high theoretical volumetric capacity. Nevertheless, unwanted dendrite growth on the Zn anode and unstable cathode materials restrict their practical application. In this study, a unique 2D MoS

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Recent technological progress towards the application of wearable electronic devices has prompted the development of flexible electrodes. To date, various technical approaches to improve the mechanical and electrical reliability of flexible electrodes have been reported; however, the transition from lab-scale processing to industrialization is still limited by complex processing steps involved in their preparation. Simple engineering steps are introduced to prepare flexible electrodes fabricated from silver-polydimethylsiloxane (Ag-PDMS) composites for wearable device applications. The electrical properties of the electrodes were investigated under stretching and bending conditions. Also, the effect of different Ag contents in the electrodes on electrical properties was investigated. As increasing the Ag content above 300 wt.%, Ag-PDMS electrodes exhibit electrical conductivity, which is closely related to the percolation threshold for the formation of a 3-D network of Ag in the PDMS matrix. Further increase of Ag content up to 450 wt.% resulted in electrical conductivity about 1000 S/cm, corresponding to an electrical resistivity of 1 mΩ cm. Furthermore, we investigated the electrical resistivity changes when repetitive stretching and bending deformation was applied. Based on the conceptual demonstration of a light-emitting diode circuit using Ag-PDMS electrodes, a simple printable electrode fabrication method can be applied to various stretchable electronic devices.

The influence of surface activated bonding (SAB) on adhesion strength between a metal and ceramic including Al/AlN and Cu/AlN is investigated. Plasma pre-treatments can significantly increase the adhesion strength between the metal and ceramic through surface activation, which can enlarge the contact area between metal and ceramic. Bonding pressure is also an important factor to improve the adhesion between metal and ceramic during SAB. Successful bonding between the metal and ceramic via SAB can be attributed to the formation of the interface layer where plastic deformation and rearrangement of metal to the ceramic occurs, which improves the atomic scale interconnection between the metal and ceramic. In this study, the influence of experimental SAB conditions for processing such as plasma power, degree of vacuum and bonding pressure on adhesion strength is investigated. Also, the thermal conduction of metal/ceramic laminates is discussed for its potential application as a heat spreader of LED chips.

The electrocatalytic performance of transition metal sulfide (TMS)–graphene composites has been simply regarded as the results of high conductivity and the large surface/volume ratio. However, unavoidable factors such as degree of oxidation of TMSs have been hardly considered for the origin of this catalytic activity of TMS–graphene composites. To accomplish the reliable application of TMS-based electrocatalytic materials, a clear understanding of the thermodynamic stability of TMS and effects of oxidation on catalytic activity is necessary. In addition, the mechanism of charge transfer at the TMS–graphene interface must be studied in depth to properly design composite materials. Herein, we report a comprehensive study of the physical chemistry at the junction of a Co1–xNixS2–graphene composite, which is a prototype designed to unravel the mechanisms of charge transfer between TMS and graphene. Specifically, the thermodynamic stability and the effects of oxidation of TMSs during the oxygen evolution react...

Sr substituted BaTiO 3 (BST) nanopowders were prepared using oxalate co-precipitation methods. During synthesis, oxygen was applied to the oxalate solution in order to control the oxidation states of Ti. Control of pH in the solution results in different crystalline phases of the powders after calcination; pure perovskite BST was obtained in the powder prepared at pH 3 solution, while perovskite BaTiO 3 (BTO) and impurities were observed in powders prepared at pH 1 solution. Phase transformation from amorphous to crystalline BST during heat treatment was discussed by different analysis technique. Also, morphology and elemental distribution of the pure BST was investigated.

Effect of Fe incorporation on electrical properties of (NixCoyMn3-x-y)O4 (NMC) spinel compound is investigated for the application to a negative temperature coefficient (NTC) thermistor. Cation distribution of the Fe doped NMC (FNMC) is calculated based on the size of ions located at tetragonal A sites and octahedral B sites in spinel structure, which can be closely related with temperature dependent electrical properties of the FNMC. With change of Fe contents, the ratio of Mn3+/Mn4+ in octahedral B site of FNMC is changed which can determine the temperature sensitivity factor (B-value). Hopping conduction mode relating with activation energy and hopping distance was also discussed depending on Fe contents, based on the small polaron hopping theory.

Given the abundance of water on the surface of the Earth, water splitting using seawater may be an effective solution to the future energy crisis. However, oxygen evolution reaction (OER) electrocatalysts require several specific characteristics to be used in seawater electrolysis, such as high catalytic activity, selectivity, and resistivity against chlorine corrosion. This paper reports that sulfur incorporation into nickel–iron layered double hydroxide (NiFe-LDH-S) can fulfill the abovementioned requirements for seawater oxidation. Sulfidation was performed on NiFe-LDH nanosheets homogeneously grown on a porous carbon scaffold via a facile chemical vapor deposition (CVD) process. The best NiFe-LDH-S sample demonstrated excellent catalytic activity with a high corrosion resistance for seawater oxidation.

(Ni,Co,Mn)O 4 (NMC) oxides were prepared by conventional sintering (CS) and spark plasma sintering (SPS) using micro and nanopowders. Small hoping polaron theory was used in order to investigate effect of processing routes on electrical properties of NMC oxides as negative temperature coefficient (NTC) thermistors. Also, X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques were utilized to analyze compositional and structural effects on the electrical properties of NMC compounds. Hopping conduction in NMC prepared by SPS and CS using nanopowder occurs via variable range hopping (VRH) mechanism, however conduction in NMC prepared by CS using micropowder follows nearest neighboring hopping (NNH) mode. Hopping distance and activation energy for the VRH mode were calculated using corresponding physical model.

The formation of cation vacancies can be useful for electro-chemical devices. In this regard, an understanding of vacancy formation is an important subject for enhancing current electrochemical devices and for developing next generation energy devices. In this work, we chose the well-known lead-free ferroelectric (K0.5Na0.5)NbO3 (KNN) as a model system to understand both the formation of cation vacancies and the relationship between cation vacancies and the physical properties. We studied sintering-duration dependence of the dielectric properties and the cation contents of KNN ceramics at the temperatures near the melting point of KNN. The difference in sintering duration led to a drastic change in the dielectric property, as well as to the creation of cation vacancies. Interestingly, we observed unequal evaporation of cations during the sintering process, which was confirmed by the data obtained from laser-induced breakdown spectroscopy. In addition, we found more drastic changes in the imaginary dielectric constant, which were likely due to a decrease in ionic conducting species, such as K and Na, in KNN.

Fe-doped Ni-Mn-Co-O (FNMC) ceramics with the formula, (Fe x Ni 0.3 Co 0.9 Mn 1.8−x , x=0.1, 0.3, 0.5, and 0.7)O 4 were synthesized using a spray drying process. Effect of Fe content on the phase evolution of FNMC compound during heat treatment was studied using X-ray diffraction. A single phase cubic spinel structure with improved crystallinity was observed when the Fe content increased over 0.5. Fe, Ni, Mn and Co ions were homogeneously distributed in the sintered the FNMC ceramics, implying no phase separation occurred during sintering. The valence state of each element was analyzed using X-ray photoelectron spectroscopy, which revealed that Ni, Co, and Fe might have a single valence state while Mn had mixed valence states in the FNMC spinel compounds. The temperature-dependent electrical resistance for the FNMC ceramics was measured. Room temperature resistance and the B-value substantially increased for the FNMC samples with Fe content higher than 0.5. The electrical properties of FNMC compounds can be optimized by controlling the Fe content, which is directly indicative of their potential role as negative temperature coefficient sensors.

Titanium dioxide (TiO2) with exposed (001) facets (TiO2(001)) has attractive photocatalytic properties. However, the high recombination rate of the photo-excited charge carriers on this surface often limits its application. Here, we report that a few-layered 1T-MoS2 coating on TiO2(001) nanosheets (abbreviated as MST) can be a promising candidate that overcomes some of the challenges of TiO2(001). Computational and experimental results demonstrate that MST as a photocatalyst exhibits a significantly low-charge recombination rate as well as excellent long-term durability. The synthesized MST 2D nanocomposites show a 31.9% increase in photocatalytic activity for hydrogen (H2) production relative to the counterpart TiO2(001). MST offers a new route for further improvement of the photocatalytic activity of TiO2 with exposed high energy facets.

Graphene oxide quantum dots (GOQDs) are usually prepared using expensive carbon precursors such as carbon nanotubes (CNT) or graphene under the strong acidic condition, which requires an additional purifying process. Here, we first develop a facile pulsed laser ablation in liquid (PLAL) technique for preparing GOQDs using earth-abundant and low-cost coal as a precursor. Only ethanol and coal are used to produce GOQDs with excellent optical properties. The prepared GOQDs exhibit excellent optoelectronic properties which can be successfully utilized in bioimaging applications.

Transition–metal-doped carbon-based electrocatalysts have attracted attention as alternatives to noble metal electrocatalysts (e.g. IrO2 and RuO2) for oxygen evolution reaction (OER) because they are inexpensive and highly efficient. However, their poor catalytic activity and time-consuming synthesis remain a challenge. Herein, we report a facile and green technique using pulsed laser ablation for preparing Ni-doped multi-walled carbon nanotubes (Ni-MWCNTs) as OER catalysts. Ni-MWCNTs exhibit high surface area, oxygen-rich functional groups (e.g., hydroxyl and carboxyl), and successful doping of Ni in the carbon framework. The as-prepared Ni-MWCNTs exhibited excellent OER catalytic performance, with an overpotential of 320 mV at the current density of 10 mA cm−2 in an alkaline medium, which is lower than that of the commercial RuO2 catalyst. Furthermore, Ni-MWCNTs displayed the initial electrocatalytic activity after 10-h stability tests, demonstrating good electrochemical durability. We believe that this work provides a simple protocol for fabricating heteroatom-doped carbon nanotubes as high-performance OER electrocatalysts.

The reliability of negative temperature coefficient (NTC) thermistors is one of the important factors for the excellent performance of the battery management system in electric vehicles. The electrical properties of the thermistor can be explained by the indirect electron jump between Mn3+ and Mn4+ at the B-sites in a spinel-type thermistor. Additionally, different types of dopants, such as Fe, Cu, Zn, Cr, and Mn, are considered as electrical modifiers that can further improve the electrical properties of the thermistor. For example, Cu is often added to NTC thermistors, occupying the octahedral sites in a spinel-type thermistor, which can play an important role in conduction with the Mn cations. Addition of Fe is also widely used in NTC thermistors owing to its high sensitivity, B constant, and stability. In this study, composition-dependent structural and electrical properties of Cu0.2/Fey-co-doped Ni0.3Mna-x-yCo0.9O4 (NMC) are investigated. Cu/Fe-co-doped NMC shows the R25 and B25/85 constant values of 4490–12730 Ω and 3185–3490 K, respectively, exhibiting a typical ρ–T curve of NTC thermistors. Higher B constant and reliable electrical stability are observed for Cu/Fe-co-doped NMC. Based on the relationship between the cationic oxidation states and electrical properties of Cu/Fe-co-doped NMC, the hopping conduction mechanism is discussed.

Diabetes is a chronic disease, which can give serious damages to the human organs that affect life expectancy. Such a life-threatening diabetes is diagnosed by systematic monitoring of blood glucose levels; thus, accurate detection of glucose within a specified target range becomes more important for glucose sensor to provide detailed information relating with diabetes, which can result in reliable decision for diabetes treatment. Thanks to many efforts developing the reliable glucose sensors, electrochemical performance of the sensor including sensitivity and selectivity in response to glucose is gradually improved. Herein, we developed spinel type NiCo2O4 (NCO) nanostructure with excellent sensitivity, selectivity and chemical robustness for glucose detection. NCO was prepared by conversion of NiCo-layered double hydroxide (NCH) at comparatively low temperature, which is synthesized by simple and facile chemical bath method and following post-heat treatment of the NCH. Electrochemical sensitivity, selectivity and detection time of the NCO in response to glucose was investigated, compared to those of the NCH. Also, long-term stability of the NCO on repetitive glucose detection was evaluated. Based on the systematic analysis on materials properties and electrochemical performance of the NCO, possible mechanism of the glucose oxidation, which significantly improves electrochemical performance of the NCO, is discussed.

The trench narrowing at sub-20 nm BEOL process has been reproduced using a FEM simulation. The trench narrowing can be observed under the conditions of both the high intrinsic stress of a hard mask and the specific design of metal line patterns with the length difference between center and side trenches. As the center trench length increases, a trench displacement takes place because trench walls have a high compressive stress gradient from the side trench surface to the center one in the direction parallel to the trench lines. The displacement also decreases with decreasing the width of the trench while increasing with decreasing the width of the low-k wall. The high pattern density of metal or dummy lines around the trenches decreases the displacement of the low-k dielectric walls. Considering the distribution of pattern densities at left and right sides of the trenches, a symmetrical pattern density deforms the trench wall more largely than an asymmetrical one. Young's modulus of SiOCH is not a sensitive factor on the trench narrowing. Our displacement analysis may be used in predicting hot spots of void defects in the Cu interconnect of real Si wafers.