Searching for tritium permeation barrier (TPB) with high tritium permeation resistance is one of the key tasks in the development of nuclear fusion reactor systems. In this study, we propose a novel N doped multi-component metal oxide coating (MCMO), where nitrogen doping can significantly improve the deuterium permeation resistance of the coating. Such a system can also be used to simulate the influence of produced N by the transmutation reaction of neutrons with oxygen in oxide TPB coating. Grazing incidence X-ray diffraction (GIXRD) analysis revealed that the phase structure of the coating remained amorphous after N doping. Through deuterium permeation testing, it was found that the coating has a very high PRF value of 12000 at 500 degrees C, which has 2.2 times enhancement in PRF compared to that of the pristine (TiVAlCrZr)O coating. Notably, the permeation process does not change the coating microstructure. Ab initio calculations reveal that the N species acts as cages to mitigate the hydrogen isotope permeation. Therefore, nitrogen doping is expected to be a new strategy to further enhance the performance of metal oxide tritium permeation barrier.

The damage to Plasma-Faced Materials (PFMs) under helium (He) plasma irradiation includes upward fuzz growth and inward He bubble erosion. While current research on PFMs mainly focuses on fuzz growth, the equally critical issue of inward erosion into materials by high-flux, low-energy He plasma irradiation is often ignored. To fill this gap, we propose He bubble erosion thickness (L) as a quantitative metric to characterize the degree of He bubble erosion in PFMs induced by He plasma, defined as the thickness difference between the pristine sample and the remaining undamaged region after irradiation. Experimental studies on tantalum (Ta) and tungsten (W) films reveal that L follows a square-root dependence on He fluence, closely linked to He diffusion and He bubble formation. Similar to the diffusion coefficient of fuzz (D), the diffusion coefficient of He bubble erosion (D ') is introduced as a new quantitative parameter for evaluating the He bubble erosion rate of PFMs. A parameter, eta, is further introduced to distinguish the dominant damage mode. Notably, designed Ta/W multilayer exhibits significantly reduced D and similar D ' values compared to W, which is attributed to semi-coherent interfaces and the formation of a Ta-W alloy within the fuzz. This study provides not only valuable parameters for PFM evaluation but also a promising strategy for designing future PFMs.

Two-dimensional (2D) transition metal carbides and nitrides (MXenes) have attracted considerable attention due to their exceptional potential in electronics, electrochemical energy storage and conversion, optics, biomedicine, and sensing. However, their structural skeleton and surface terminations are highly sensitive to temperature, and thermally induced structural evolution can profoundly modify their physicochemical properties and device performance. Consequently, analytical methods capable of accurately identifying and continuously monitoring the structural dynamics of MXenes are urgently required. Within this context, Raman spectroscopy has emerged as a powerful and accessible technique for sensitively probing MXene lattice vibrations and surface chemistry. Using Ti3C2Tx as a model MXene, this study employs in situ and quasi-in situ Raman spectroscopy to systematically elucidate its temperature-dependent structural evolution during thermal annealing. The Raman response captures a series of sequential transformations triggered by heating, including interlayer water removal, depletion of -OH terminations accompanied by the growth of =O groups, loss of -F terminations, formation of C-C bonds, lattice oxidation, and eventual TiO2 formation. By tracking the shifts and intensity variations of characteristic Raman modes, distinct structural states across the thermal evolution pathway are resolved, enabling the construction of a comprehensive spectral fingerprint that delineates the entire heat-driven transformation process. These in situ Raman insights not only deepen the fundamental understanding of MXene thermal stability and structural evolution mechanisms but also provide an essential diagnostic basis and practical guidance for optimizing their performance and stability in electronic devices, electrochemical energy-storage systems, and sensing applications.

Exploring efficient bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions is key to water electrolysis. However, the inherently slow reaction kinetics of electrocatalysis are constrained by the mass transfer limitation and unsuitable adsorption/desorption dynamics. Herein, a Fe-doped-Ni3S2/NiFeCoCeIn oxide hydroxide (FNS/HEOXY) crystalline–amorphous heterostructure electro-catalyst with a large work function difference (ΔΦ) and strong built-in electric field (BEF) is successfully designed and synthesized. Benefiting from the electron transfer behavior from FNS to HEOXY, the FNS/HEOXY shows outstanding catalytic activity for both hydrogen and oxygen evolution, along with ultra-high stability in an alkaline medium at an industrial-level current density. Moreover, the anion exchange membrane water electrolyzer (AEMWE) assembled by the FNS/HEOXY requires only a minimal cell voltage of 1.83 V to reach 1 A cm−2 at 80 °C. Both experimental and theoretical results confirm the interfacial charge redistribution induced by the strong BEF, thus finely optimizing the adsorption energy. This work proposes a new design principle toward efficient electrocatalysts for energy conversion.

Developing high performance plasma facing materials (PFMs) is one of the greatest challenges for fusion reactors because PFMs face unprecedented harsh environments. In this work, the radiation resistance of tungstencontaining amorphous refractory multi-component alloy film was studied by He plasma irradiation. The amorphous TiZrHfTaW film was evaluated by 50 eV helium plasma irradiation at 1275 K. The invaded helium atoms quickly diffuse inside the film delaying the formation of large He bubbles near surface and its break to form fuzz. Instead, He migrates and merges to form large number of relatively small helium bubbles, leading to the formation of nanoporous structures, which blocks the diffusion of He. This new "migration-blocking" strategy in the amorphous TiZrHfTaW film greatly slowing down the growth of fuzz. The threshold fluence for forming fuzz structure in TiZrHfTaW film is increased greatly to 20 times higher and the length of fuzz irradiated to the fluence of 3 x 1026 ions/m2 is 28 times shorter than those of bulk W. The presented results provide an idea for development of amorphous refractory multi-component alloys as a new kind of radiation resistant PFMs and trigger further study on it.

Based on over 70,000 h of creep testing data at 700 degrees C, the microstructural stability and creep performance of a C700R-1 alloy, designed for 700 degrees C advanced ultra-supercritical steam (A-USC) turbine rotors, were investigated during long-term aging. The isothermal extrapolated creep rupture strength of C700R-1 alloy at 700 degrees C for 100,000 h exceeds 180 MPa. C700R-1 alloy exhibits excellent long-term microstructural stability at 700 degrees C. The coarsening of gamma'-phase particles follows the Lifshitz-Slyozov-Wagner (LSW) theory, with particle sizes remaining below 150 nm even after 100,000 h of aging. Grain boundary carbides coarsened during the aging process at 700 degrees C, and after 33,888 h of aging, short rod-shaped M6C carbides and irregular short rod-shaped mu-phase precipitates were observed within the grains. However, these precipitates did not appear to have a detrimental effect on the alloy's creep rupture strength.

The utilization of two-dimensional van der waals heterostructures in optoelectronic synapses allows for the integration of information processing and memory, thereby providing novel operating platforms for simulating the perceptual visual systems and developing the neuromorphic computing systems due to its contactless, highly efficient and parallel computing. Herein, we have constructed a straightforward MoS2/WS2 heterostructure optoelectronic synapse and examined its capacity to imitate synaptic behaviors under optical stimulus. The MoS2/WS2 device demonstrated several synaptic functions, such as the excitatory postsynaptic current, short-term plasticity, long-term plasticity, pairs-pulse facilitation and 'learning-experience' behavior. Moreover, the MoS2/WS2 synaptic device can achieve a wide range of photo response wavelengths, spanning from UV to visible light, as well as the conversion from short-term plasticity to long-term plasticity. Furthermore, light-induced charge transfer due to adsorption and desorption of oxygen molecules in MoS2/WS2 heterostructure can be used to explain its working mechanism. Additionally, the synaptic plasticity of MoS2/WS2 device can be controlled by adjusting the duration, power and number of the optical pulses, which renders the MoS2/WS2-based optoelectronic synaptic device extremely favorable for implementation in the perceptual visual system.

Recently, 2D heterojunction materials have significant potential for application in humidity sensors due to their sensitive interface current regulation characteristics. Enhancing the contribution of the junction to the conductivity in the material is crucial for optimizing sensing performance. In this study, the n-n heterojunction of MoSe2@MoS2 with a unique 3D interface structure was successfully prepared using a hydrothermal method to increase the heterojunction content. The heterojunction improves the charge transfer at the interface, enhances the sensitivity of the material, and shortens the gas response/recovery time. The sensitivity of MoSe2@MoS2 with 3D heterojunction is one order of magnitude higher than that of single-phase MoSe2, and its response (recovery) time is shortened from 55 s (51 s) to 30 s (33 s) compared with single-phase MoS2. Furthermore, by optimizing the ratio of MoSe2 and MoS2 in the material, the contribution of heterojunctions to conductivity has been increased, thus enhancing the performance of gas sensing. More importantly, the sensing mechanism was deeply analyzed by exploring the changes of energy band and barrier before and after the sensor response.

Download This Paper Open PDF in Browser Add Paper to My Library Share: Permalink Using these links will ensure access to this page indefinitely Copy URL Copy DOI

The performance of plasma-facing materials (PFMs) is one of the key factors that significantly impact the stability of operation in fusion reactors. Herein, a new CrMoTaWV/W (high entropy alloy (HEA)/W) multilayer structure is designed as PFM to investigate its resistance to He plasma irradiation. It was observed that the introduction of the interfaces effectively absorbed plenty of He atoms, preventing them from diffusing into the material and delaying the formation of fuzz incubation zone, therefore, enhancing the resistance to plasma irradiation. The thickness transformed to fuzz in the HEA/W multilayer films was observed to be about two-thirds of those in the CrMoTaWV (HEA) film. Additionally, the fuzz growth rates in HEA/W multilayer films are lower than the average growth rate of bulk W and HEA films combined. These findings highlight a promising new avenue for the exploration of high-performance PFMs.

While memcapacitors exhibit scalability, a sneak-path-free nature, and lower power consumption compared to memristors, the sensitivity and responsiveness of conventional memcapacitors are lower than expected due to their physical mechanisms. Quantum capacitance, which is controlled by the Fermi level and the density of states, holds the potential to enhance memcapacitor performance and address these issues. In this study, a unique memcapacitor based on the MoS2 quantum capacitance (MoS2 quantum memcapacitor, MQM) is proposed, and the “learning-forgetting” behavior of simulated synapses is discussed. Initially, the quantum capacitance memory effect of MoS2 was demonstrated. Subsequently, under gate voltage (Vg) control, the MQM exhibited a sensitive response and excellent repeatability. Finally, the MQM demonstrated a range of artificial synaptic behaviors consistent with biological synapses, including transformations from short-term potentiation to long-term potentiation and from short-term depression to long-term depression, as well as high pair-pulse-facilitation behavior. This showcases its excellent versatility and flexibility, thereby promoting the development of an integrated artificial neural network.

It is imperative to study neuromorphic devices where the behavior of artificial synapses is regulated by external conditions. The quantum capacitance of 2D materials is determined by the local density of states near the Fermi level and usually exhibits a sensitive response to external stimuli. This study explores the use of MoS2 quantum capacitance in a memcapacitor (MoS2 quantum memcapacitor, MQM), emulating biological synapse behavior and showcasing higher sensitivity. Notably, without altering the physical structure, MQM realizes the potentiation and depression of capacitance through light and gas coupling manipulation, establishing a memory effect for the device. This enables MQM to reproduce the learning-forgetting cycle multiple times with good repeatability. Moreover, MQM can simulate various biological synaptic behaviors, encompassing short-term memory to long-term memory conversions, short-term depression to long-term depression conversions, and higher pair-pulse-facilitation behavior. These characteristics offer a fresh direction and possibilities for artificial synaptic device research.

The heavy micro‐titanium‐carbide ( TiC) particles are first introduced into brush‐electroplated Zn–Ni coating (TiC‐0 coating) by using some surfactants here. The effect of TiC concentration of brush‐electroplating solution on the properties of Zn–Ni–TiC coatings is investigated. It is found that the coating hardness and corrosion resistance are enhanced significantly due to the co‐deposition of TiC and an optimal coating with a thickness of 71 μm and adhesive strength of 37.2 MPa is obtained when TiC concentration was 40 (g L −1 ) (TiC‐40 coating). The pencil hardness of TiC‐0 and TiC‐40 is 2 H and 5 H, respectively. The corrosion resistance time to hot NH 4 NO 3 solution (or inferred neutral salt spray) of TiC‐0 and TiC‐40 are 40 and 240 min (or 321 and 1995 h), respectively. Many pores appear on the coating due to the incomplete overlap of many batch layers. The TiC content is the factor dominating the coating hardness and corrosion resistance by changing the structure, contact angle, and pore diameter of coating, thereby changing the linear polar resistance R p from potentiodynamic polarization curves, charge‐transfer resistance R ct or |Z| 0.01 Hz , or polarization resistance from electrochemical impedance spectroscopy. The content of Zn–Ni alloy is the factor dominating the adhesive strength of Zn–Ni–TiC coating.

Revealing the mechanism of the interface-type resistive switching remains challenging due to the difficulties in direct observation of the buried interface. As a transparent conductive electrode, monolayer MoS2 is suitable for studying resistance switching mechanisms directly at the interface due to its atomic-sized thickness and electron transfer sensitivity. In this study, a memory device based on the MoS2/Nb:SrTiO3 heterojunction was constructed. An apparent hysteresis loop can be observed, along with resistive switching phenomenon between high resistance state and low resistance state. In addition, the surface potential of MoS2 also varies significantly as the resistance state changes. Furthermore, the evolution of PL spectrum in MoS2 under electric fields presents a shift with the resistance state. Finally, using the sensitive response of the MoS2 monolayer, interface charge trapping/ detrapping mechanism in MoS2/Nb:SrTiO3 heterojunction was confirmed.

Finding high performance plasma-facing materials (PFMs) is one of the most important and challenging tasks for realizing the commercial application of fusion reactors. Herein, we found the CrMoTaWV high entropy alloy (HEA) is highly resistant to low-energy and high-flux He plasma exposure. The nanochannel HEA film has 20 times higher initial fluence for the formation of fuzz and a remarkable 8.9 times slower fuzz growth rate than those of W. Combining the in-situ TEM observation and the Molecular dynamics (MD) simulation of the He bubble growth process, a new mechanism for the enhanced radiation resistance in HEA with the unusual interaction between HEA and He is found, where, differing from traditional metal, bubble growth in HEA leads to non-directional emission of interstitial atoms while HEA greatly suppress the growth of He bubbles. The special nanochannel structure further rise the radiation resistance through releasing He out of the HEA film and reducing the He concentration. This new nanochannel refractory HEA material presents a promising choice as the PFMs with excellent performance and a much longer serving lifetime for future commercial fusion reactors.

The influence of the interface contact condition on the resistive switching (RS) effects of metal/Nb:SrTiO3 heterojunctions was investigated. Two Au/Nb:SrTiO3 samples with or without in situ substrate cleaning treatment were fabricated. Through comparative analysis of I–V hysteresis and switching performance, it was observed that the RS effect in the heterojunction formed by the in situ cleaned Nb:SrTiO3 substrate was significantly weakened. In addition, the SEM image demonstrates intimate contact between metal and the in situ cleaned substrate. In contrast, the untreated Au/Nb:SrTiO3 interface exhibits poor contact. The poor contact, as confirmed by interface AFM and CAFM images, is responsible for the resistive switching observed. Our research provides an innovative approach to elucidating the mechanism of the resistive switching effect, which will pave the way for better application of the device.

Experimental and theoretical studies have shown that helium (He) atoms in metal tend to form into nano-sized bubbles which greatly affects mechanical properties of metals. Thus, designing nanostructure to control the growth of He bubbles and increase its radiation resistance is an important task. In this work, we systematically study the atomistic mechanism on how the carbon (C) nanomaterials embedded inside metals with different crystal structures (FCC-Ni and BCC-Fe) disperse or release He atoms using molecular dynamics simulations. The dynamic evolution of He atoms in different Ni/C and Fe/C nanocomposites were observed and compared. It is found that the presence of multiple C-72 with vacancy defects and graphene with multiple vacancy defects can suppress the formation of large He bubbles and dislocations by helping to disperse He atoms, while, the C nanotube with vacancy defects can suppress the formation of large He bubbles and dislocations by helping to release He atoms. The formation energies of He in different Ni/C and Fe/C nanocomposites were also calculated to explain why the He atoms tend to diffuse into the region near C structures. The average diffusion coefficients of He in bulk Ni and bulk Fe were calculated to explain the mechanism for the better abilities of C structures in Ni/C nanocomposites than in Fe/C nanocomposites help to disperse or release He atoms.

Developing ceramic coating with high hydrogen isotopes permeation resistance is an urgent task in many fields such as fusion reactor systems, hydrogen storage/transportation, and fuel cell. In this work, a (TiVAl-CrZr)O multi-component metal oxide glass (MCMOG) coating is developed as a new type of hydrogen isotopes permeation barrier (HIPB), and the diffusion behavior of deuterium in MCMOG is studied for the first time. Compared with the deuterium permeation reduction factor (DPRF) of 51 for amorphous alumina coating (at 587 degrees C in 0.65 mu m), the 29 nm dense MCMOG coating has around 27 times en-hancement with DPRF of 1420 at 550 degrees C. Based on first-principles calculations, we show that the sig-nificantly suppressed deuterium permeation in MCMOGs is attributed to the sluggish diffusion of deu-terium arising from the highly rugged energy landscape, which is induced by the diversity of electronic band structures near the Fermi level. In addition, oxygen vacancies strongly affect PRF, where the PRF of the fully oxidized MCMOG layer (29 nm) is around 200 times compared to that of MCMOG with the same thickness containing oxygen vacancies. Therefore, dense MCMOG is a new promising HIPB material. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Oxygen evolution reaction (OER) is an obstacle to the electrocatalytic water splitting due to its unique four-proton-and-electron-transfer reaction process. Many methods, such as engineering heterostructure and introducing oxygen vacancy, have been used to improve the catalytic performance of electrocatalysts for OER. Herein, the above two kinds of regulation are simultaneously realized in a catalyst by using unique ion irradiation technology. A nanosheet structured NiO/NiFe2 O4 heterostructure with rich oxygen vacancies converted from nickel-iron layered double hydroxides by Ar+ ions irradiation shows significant enhancement in both OER and hydrogen evolution reaction performance. Density functional theory (DFT) calculations reveal that the construction of NiO/NiFe2 O4 can optimize the free energy of O* to OOH* process during OER reaction. The oxygen vacancy-rich NiO/NiFe2 O4 nanosheets have an overpotential of 279 mV at 10 mA cm-2 and a low Tafel slope of 42 mV dec-1 . Moreover, this NiO/NiFe2 O4 electrode shows an excellent long-term stability at 100 mA cm-2 for 450 h. The synergetic effects between NiO and NiFe2 O4 make NiO/NiFe2 O4 heterostructure have high conductivity and fast charge transfer, abundant active sites, and high catalytic reactivity, contributing to its excellent performance.