Search Results (210)

The development of advanced energy materials is critical for the safety and efficiency of next-generation nuclear energy systems. Aluminum alloys present a compelling option due to their excellent neutronic properties, notably a low thermal neutron absorption cross-section. However, their historically poor high-temperature performance has limited their use in commercial power reactors. This makes them prime candidates for specialized, lower-temperature but high-radiation environments, such as research reactors, spent fuel storage systems, and spallation neutron sources. In these applications, mitigating radiation damage—particularly swelling and embrittlement from helium produced during irradiation—remains a paramount challenge. Grain Boundary Engineering (GBE) is a potent strategy to mitigate radiation damage by increasing the fraction of low-energy Coincident Site Lattice (CSL) boundaries. These interfaces act as effective sinks for radiation-induced point defects (vacancies and self-interstitials), suppressing their accumulation and subsequent clustering into damaging dislocation loops and voids. By controlling the defect population, GBE can substantially reduce macroscopic effects like volumetric swelling and embrittlement, enhancing material performance in harsh radiation environments. In this article we evaluate the efficacy of GBE in an AlSi10Mg alloy, a candidate material for nuclear applications. Samples were prepared via KOBO extrusion, with a subset undergoing subsequent annealing to produce varied initial grain sizes and grain boundary character distributions. This allows for a direct comparison of how these microstructural features influence the material’s response to helium ion irradiation, which simulates damage from fission and fusion reactions. The resulting post-irradiation defect structures and their interaction with the engineered grain boundary network were characterized using a combination of Transmission Electron Microscopy (TEM) and High-Resolution Transmission Electron Microscopy (HRTEM), providing crucial insights for designing next-generation, radiation-tolerant energy materials. Full article

Non-precious catalysts for alkaline hydrogen evolution reaction (HER) face a fundamental multi-scale challenge: lack of synergy between electronic structure tuning for balancing H adsorption and water dissociation, active site stabilization for boosting intrinsic turnover frequency (TOF), and mass transport. Even Pt loses 2–3 orders of magnitude activity in alkaline media due to inefficient water dissociation, a synergistic gap unresolved by the Sabatier principle alone. Existing strategies only address isolated aspects: phase engineering optimizes electronic structure but not active site stability; heteroatom doping introduces defects unlinked to mass transport; and nanostructuring enhances mass transfer but not atomic-level activity. None of them address multi-scale mechanistic synergy. Herein, we design a hierarchically porous P-doped NiCo alloy (hpP-NiCo) with an aim of achieving this synergy via integrating α-FCC/ε-HCP phases, P-induced defects, and 3D porosity. The formed α/ε interface tunes the d-band center to balance H adsorption and water dissociation; and the doped P stabilizes metal-vacancy sites to boost TOF. In addition, porosity matches mass transport with active site accessibility. In 1 M KOH, hpP-NiCo reaches 1000 mA cm⁻² at 185 mV overpotential and has a Tafel slope of 43.1 mV dec⁻¹, corresponding to electrochemical desorption as the rate-limiting step and verifying Volmer acceleration. Moreover, it also exhibits bifunctional oxygen evolution reaction (OER), achieving 100 mA cm⁻² at potential of 1.55 V. This work establishes a mechanistic synergy model for non-precious HER catalysts. Full article

Here, the effects of Fe vacancy defects on the bonding properties of γ-Fe (111)/α-Al₂O₃ (0001) interfaces are studied in depth at the atomic and electronic levels using first-principles calculations. The first (V₁), second (V₂), third (V₃), and fourth (V₄) layers of vacancy structures within the Fe substrate, as well as the ideal Fe/Al₂O₃ interface structure, are proposed and contrasted, including their thermodynamic parameters and atomic/electronic properties. The results demonstrate that the presence of vacancies in the first atomic layer of Fe deteriorates the interfacial bonding strength, whereas vacancies situated in the third layer enhance the interfacial bonding strength. The effect of vacancy beyond the third layer becomes negligible. This occurs mainly because vacancy defects at different positions induce the relaxation behavior of atoms, resulting in bond-breaking and bond-forming reactions at the interface. Following that, the formation process of vacancies can cause the transfer and rearrangement of the electrons at the interface. This process leads to significant changes in the charge concentration of the interfaces, where V₃ is the largest and V₁ is the smallest, indicating that the greater the charge concentration, the stronger the bonding strength of the interface. Furthermore, it is discovered that vacancy defects can induce new electronic orbital hybridization between Fe and O at the interface, which is the fundamental reason for changes in the properties of the interface. Interestingly, it is also found that more electronic orbital hybridization will strengthen the bonding performance of the interface. It seems, then, that the existence of vacancy defects not only changes the electronic environment of the Fe/Al₂O₃ interface but also directly affects the bonding properties of the interface. Full article

Photocatalytic conversion of CO₂ to hydrocarbon fuels offers a promising pathway for sustainable renewable energy production. In this study, a ZnO/ZnFe₂O₄ composite featuring a Type-II heterojunction was synthesized through a facile one-step hydrothermal approach, significantly enhancing visible-light-driven CO₂ reduction activity. The optimized catalyst exhibits CH₄ and CO production rates that are 3.3 and 4.9 times higher, respectively, than those of pristine ZnFe₂O₄ over 6 h. This significant enhancement in photocatalytic performance is attributed to the Type-II band alignment, which not only broadens light absorption but also greatly promotes efficient charge separation. It is corroborated by a series of experimental evidence: a two-fold enhancement in photocurrent response, a 15.1% reduction in PL intensity, decreased electrochemical impedance, and an extended charge carrier lifetime. Furthermore, in situ FTIR spectroscopy confirms that the heterojunction facilitates the formation of key intermediates (specifically *COOH and HCOO⁻). This study highlights the importance of precise interface design based on a Type-II heterojunction in heterostructured composite catalysts and provides mechanistic insights for developing highly efficient CO₂ photoreduction systems. Full article

Ultrathin oxide semiconductors are promising channel materials for next-generation thin-film transistors (TFTs), but their performance is severely limited by bulk and interface defects as the channel thickness approaches a few nanometers. In this study, we show that high-pressure hydrogen annealing (HPHA) effectively mitigates these limitations in 3.6 nm thick ZnO TFTs. HPHA-treated devices exhibit a nearly four-fold increase in on-current, a steeper subthreshold swing, and a negative shift in threshold voltage compared to reference groups. X-ray photoelectron spectroscopy reveals a marked reduction in oxygen vacancies and hydroxyl groups, while capacitance–voltage measurements confirm more than a three-fold decrease in interface trap density. Low-frequency noise analysis further demonstrates noise suppression and a transition in the dominant noise mechanism from carrier number fluctuation to mobility fluctuation. These results establish HPHA as a robust strategy for defect passivation in ultrathin oxide semiconductor channels and provide critical insights for their integration into future low-power, high-density electronic systems. Full article

Current Pt-based methane combustion catalysts require high noble metal loadings (≥1 wt%) and exhibit insufficient low-temperature activity. To address this, we developed a 0.5 wt% Pt catalyst supported by sulfate-modified Fe-Ce-TiO₂ (denoted 0.5Pt/CFT-TS) via sol–gel synthesis using titanium oxysulfate (TiOSO₄) precursor. Control catalysts prepared with TiCl₄, titanium butoxide, or commercial TiO₂ showed inferior performance. Structural characterization revealed that the TiOSO₄ derived carrier possesses a mesoporous framework (156.2 m²/g surface area, 8.1 nm pore size) with residual SO₄²⁻ inducing strong Brønsted acidity (1.23 mmol/g NH₃ adsorption) and elevated Ce³⁺ concentration (49.45%). These properties synergistically enhanced oxygen vacancy density (51.16% O_α fraction) and stabilized sub-nm Pt nanoparticles. The resulting Pt⁰-Fe³⁺/Ce⁴⁺-Oᵥ interface facilitated dynamic redox cycling (Fe³⁺ + Ce⁴⁺ + 0.5O²⁻ ⇌ Fe²⁺ + Ce³⁺ + 0.5Oᵥ + 0.25O₂), lowering oxygen vacancy regeneration barriers (H₂-TPR peak reduced by 45 °C) and decreasing methane activation energy to 46.77 kJ/mol. This catalyst achieved T₉₀ = 163 °C and complete conversion at 450 °C under industrial conditions (1% CH₄/4% O₂, GHSV = 30,000 h⁻¹), establishing a novel design strategy for low-Pt combustion catalysts. Full article

Trap states in 2D transition metal dichalcogenides significantly affect the responsivity and response time of photodetectors, and previous ReS₂/Si-based heterojunction photodetectors have struggled to simultaneously achieve high responsivity and fast response. To address this issue, we developed a n-type ReS₂/p-type Si heterojunction photodetector through interface engineering. Specifically, the silicon substrate with a silicon dioxide dielectric layer was treated with inductively coupled soft plasma to adjust the thickness and surface states of the dielectric layer. This treatment created a multilayered heterostructure, which increased carrier concentration, effectively passivated sulfur-vacancy-induced defects, and thereby improved responsivity. Experimental results showed that the silicon-based n-type ReS₂ photodetector achieved a responsivity of 0.88 A W⁻¹ with a rapid response rise time of 2.5 s, a significant improvement from the intrinsic values of 12 mA W⁻¹ responsivity and 6 s rise time. Additionally, due to the defect-tunable nature of this pretreatment technique, the device exhibited enhanced Raman peaks and intensified photoluminescence (PL) absorption features, confirming the effectiveness of the interface engineering in optimizing device performance. Full article

Surface-enhanced Raman Scattering (SERS) enables ultrasensitive detection but is often hindered by biocompatibility and sustainability concerns due to its reliance on noble metal substrates. To overcome these limitations, we develop a semiconductor-based SERS platform utilizing ultrathin tungsten trioxide (WO₃) nanofilms synthesized via a facile annealing process on fluorine-doped tin oxide (FTO). This system achieves an impressive Raman enhancement factor of 1.36 × 10⁶, enabling ultrasensitive detection of rhodamine 6G (R6G) and methylene blue (MB) at ultralow concentrations, surpassing conventional metal-based SERS platforms. It is further suggested that this is a substrate that can be easily coupled to other metals. An application for the detection of adenine molecules is realized through layered WO₃-Au NPs composites, where embedded gold nanoparticles act as plasma “hot spots” to amplify the sensitivity. Density functional theory (DFT) calculations and band structure analysis confirm that synergistic interface charge transfer and naturally formed oxygen vacancies enhance performance. By combining semiconductor compatibility with other metal amplification, this WO₃-based SERS platform offers a sustainable and high-performance alternative to conventional substrates, paving the way for environmentally friendly and scalable Raman sensing technologies. Full article

As a model compound for lignin derivatives, anisole and its conversion are crucial for the upgrading of biomass resources. Anisole molecule contains a characteristic aryl ether bond (C_aryl-O-CH₃); therefore, the selective cleavage of the C-O bond to efficiently produce high-value chemicals poses a significant challenge. Constructing bimetallic synergistic active sites through tuning the metal-support interface is considered an effective strategy. In this work, the WO₃-promoted Pt/SiO₂ catalysts were investigated to enhance the performance of anisole hydrodeoxygenation (HDO) to hydrocarbons. Experimental results demonstrate that WO₃ significantly promotes HDO selectivity, increasing from 37.8% to 86.8% at 250 °C. Moreover, moderate doping improves low-temperature (<250 °C) HDO activity, confirming the presence of synergistic effects. In contrast, excessive WO₃ suppresses anisole conversion. Characterization results reveal that WO₃ stabilizes metallic Pt and facilitates H₂ dissociation. Concurrently, strong hydrogen spillover between Pt and WO₃ promotes oxygen vacancy formation on WO₃. This transforms disordered adsorption of anisole on SiO₂ into directed adsorption of the anisole’s oxygen species onto WO₃. This work achieves high anisole HDO selectivity through the Pt-WO₃ interface tuning, offering novel insights for efficient lignin conversion. Full article

Developing photocatalysts with both high efficiency and reaction pathway selectivity is essential for achieving efficient and sustainable CO₂ conversion. By incorporating sulphur vacancies into MoS₂, an S-scheme heterojunction photocatalyst (MoS₂-SVs/g-C₃N₄) was developed, achieving efficient and selective CO₂ photoreduction to CH₃OH. The structural and photoelectronic characterisation of the system shows that the heterogeneous interface between MoS₂ and g-C₃N₄ is in close contact. The introduction of SVs effectively modulates the electronic structure and surface activity of MoS₂, which in turn enhances the CO₂ reduction performance. Optical and electronic structure analyses reveal that the heterojunction promotes favourable band alignment and interfacial electric potential gradients, which together suppress charge recombination and enhance directional carrier separation. Under irradiation, the MoS₂-SVs/g-C₃N₄ photocatalyst exhibited outstanding photocatalytic CH₃OH production with a yield of 10.06 μmol·h⁻¹·g⁻¹, significantly surpassing the performance of control samples while demonstrating excellent product selectivity and remarkable stability. Mechanistic studies further verify that vacancy-induced energy band modulation with Fermi energy level enhancement significantly reduces the multi-electron transfer barrier, thus preferentially driving the CH₃OH generation pathway. This work proposes a universal structural design strategy that synergistically coordinates vacancy engineering with band structure modulation, establishing both theoretical principles and practical methodologies for developing selective multi-electron CO₂ reduction systems. Full article

In order to improve the electrochromic properties of NiO_x films, Mg ions were introduced into NiO_x films using the sol–gel method and the spin-coating method. The introduction of Mg ions leads to the loose structure of the compact NiO_x film, which can provide more channels for the transport of OH⁻. In addition, the introduction of Mg ions increases the oxygen vacancies and oxygen interstitial defects in the NiO_x film, which effectively increases the reactive sites and improves the charge transfer efficiency at the interface between the NiO_x film and the electrolyte. The electrochemical results further show that the film electrode (NiO_x-Mg2) has the largest charge storage capacity when the Mg doping concentration is 10%. Compared with the undoped NiO_x film, the doping of Mg improves the transmittance modulation (ΔT) performance of the NiO_x film (ΔT up to 55.8%) and shortens the response time (2.39 s/0.63 s for coloring/bleaching). In general, Mg doping is an effective method for improving the electrochromic properties of NiO_x films. Full article

A concept towards current measurement in low and medium voltage power distribution networks is presented. The concentric magnetic field around the current-carrying conductor should be measured using a nitrogen-vacancy quantum magnetic field sensor. A bottleneck in current measurement systems is the readout electronics, which are usually based on optically detected magnetic resonance (ODMR). The idea is to have a hardware that tracks up to four resonances simultaneously for the detection of the three-axis magnetic field components and the temperature. Normally, expensive scientific instruments are used for the measurement setup. In this work, we present an electronic device that is based on a Zynq 7010 FPGA (Red Pitaya) with an add-on board, which has been developed to control the excitation laser, the generation of the microwaves, and interfacing the photodiode, and which provides additional fast digital outputs. The T1 measurement was chosen to demonstrate the ability to read out the spin of the system. Full article

The widespread adoption of sodium-ion batteries (SIBs) remains constrained by the inherent limitations of conventional anode materials, particularly their inadequate electronic conductivity, limited active sites, and pronounced structural degradation during cycling. To overcome these limitations, we propose a novel redox engineering approach to fabricate oxygen-vacancy-rich SnO₂ dots anchored on reduced graphene oxide (rGO), which are encapsulated within N-doped carbon nanofibers (denoted as ov-SnO₂/rGO@N-CNFs) through electrospinning and subsequent carbonization. The introduction of rich oxygen vacancies establishes additional sodium intercalation sites and enhances Na⁺ diffusion kinetics, while the conductive N-doped carbon network effectively facilitates charge transport and mitigates SnO₂ aggregation. Benefiting from the well-designed architecture, the hierarchical ov-SnO₂/rGO@N-CNFs electrode achieves remarkable reversible specific capacities of 351 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹ and 257.3 mAh g⁻¹ after 2000 cycles at 1.0 A g⁻¹ and maintains 177 mAh g⁻¹ even after 8000 cycles at 5.0 A g⁻¹, demonstrating exceptional long-term cycling stability and rate capability. This work offers a versatile design strategy for developing high-performance anode materials through synergistic interface engineering for SIBs. Full article

Memristors with resistive switching capabilities are vital for information storage and brain-inspired computing, making them a key focus in current research. This study demonstrates non-volatile analog resistive switching behavior in Al/TiO_x/TiN/Si(n⁺⁺)/Al memristive devices. Analog resistive switching offers gradual, controllable conductance changes, which are essential for mimicking brain-like synaptic behavior, unlike digital/abrupt switching. The amorphous titanium oxide (TiO_x) active layer was deposited using the pulsed-DC reactive magnetron sputtering technique. The impact of increasing the oxide thickness on the electrical performance of the memristors was investigated. Electrical characterizations revealed stable, forming-free analog resistive switching, achieving endurance beyond 300 DC cycles. The charge conduction mechanisms underlying the current–voltage (I–V) characteristics are analyzed in detail, revealing the presence of ohmic behavior, Schottky emission, and space-charge-limited conduction (SCLC). Experimental results indicate that increasing the TiO_x film thickness from 31 to 44 nm leads to a notable change in the current conduction mechanism. The results confirm that the memristors have good stability (>1500 s) and are capable of exhibiting excellent long-term potentiation (LTP) and long-term depression (LTD) properties. The analog switching driven by oxygen vacancy-induced barrier modulation in the TiO_x/TiN interface is explained in detail, supported by a proposed model. The remarkable switching characteristics exhibited by the TiO_x-based memristive devices make them highly suitable for artificial synapse applications in neuromorphic computing systems. Full article

This work investigates the impact of an internal electric field on the annihilation characteristics of positrons implanted in a $180\left(10\right)\mathrm{nm}$ SiO₂ layer of a Metal-Oxide-Silicon (MOS) capacitor, using Positron Annihilation Lifetime Spectroscopy (PALS). By varying the gate voltage, electric fields up to $1.72\mathrm{MV}/\mathrm{cm}$ were applied. The measurements reveal a field-dependent suppression of positronium (Ps) formation by up to $64\%$, leading to an enhancement of free positron annihilation. The increase in free positrons suggests that vacancy clusters are the dominant defect type in the oxide layer. Additionally, drift towards the SiO₂/Si interface reveals not only larger void-like defects but also a distinct population of smaller traps that are less prominent when drifting to the Al/SiO₂ interface. In total, by combining positron drift with PALS, more detailed insights into the nature and spatial distribution of defects within the SiO₂ network and in particular near the SiO₂/Si interface are obtained. Full article