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The Mn X Tm 1‒X Se (0 ≤ Х ≤ 0.2) solid solutions have been first synthesized and their structural, magnetic, and transport properties have been studied in the temperature range of 80–1000 K and magnetic fields of up to 12 kOe. The surface morphology of the samples has been examined and the chemical analysis has been carried out. It is shown that the valence change with the increasing substitution concentration is accompanied by a change in the lattice parameter and a decrease in the magnetic moment of the samples. The Kondo temperatures caused by the manganese and thulium subsystem have been found in the low- and room-temperature regions. The temperature of localization of small-radius polarons has been determined. A drastic decrease in the relaxation time in the range of the manganese ion percolation through the lattice in the Mn X Tm 1‒X Se system has been established. The change of the current carrier type upon variation in the temperature and substitution concentration was determined from the Seebeck coefficient. A high-temperature extremum of thermopower was revealed, which is explained within the framework of the Anderson model. [ABSTRACT FROM AUTHOR]

Improving the deflection performance of a beam deflector is urgently required to acquire optical signals for space laser communication and change the attitude and position of space targets and spacecraft. In this work, a Cu-doped potassium tantalate niobate (Cu-KTN) single crystal with fast photochromic and increased beam deflection properties is synthesized using the top-seeded solution growth method. When a Cu-KTN single crystal is irradiated with 405 nm light or ultraviolet (UV) light, the color changes from pale green to reddish brown. After light irradiation, the color gradually returns to yellowish green. Decolorization is accelerated under irradiation with green light or long-wavelength light, and the color changes to pale green. The origin of reversible photochromism reveals the fast valence change of Cu ions. In addition, ion doping improves the beam deflection angle of the secondary electro-optical effect of Cu-KTN (4.3 mrad, 1000 V) crystal compared with pure KTN (3.2 mrad, 1000 V). This study successfully synthesizes Cu-KTN single crystals with photochromic uses and establishes a new route for beam deflectors with significant deflection angles. Cu-KTN single crystals synthesized using the top-species solution growth method. They are reddish brown under 405 nm light/UV excitation and pale green under green/red light irradiation, exhibiting a controlled and reversible fast photochromic response. Ion doping increases the beam deflection angle of Cu-KTN (4.3 mrad, 1000 V). [Display omitted] [ABSTRACT FROM AUTHOR]

Homogeneous mixed-valence (MV) behaviour is one of the most intriguing phenomena of f-electron systems. Despite extensive efforts, a fundamental aspect which remains unsettled is the experimental determination of the limiting cases for which MV emerges. Here we address this question for SmB6, a prototypical MV system characterized by two nearly-degenerate Sm2+ and Sm3+ configurations. By combining angle-resolved photoemission spectroscopy (ARPES) and x-ray absorption spectroscopy (XAS), we track the evolution of the mean Sm valence, vSm, in the SmxLa1−xB6 series. Upon substitution of Sm ions with trivalent La, we observe a linear decrease of valence fluctuations to an almost complete suppression at x = 0.2, with vSm ~ 2; surprisingly, by further reducing x, a re-entrant increase of vSm develops, approaching the value of vimp ~ 2.35 in the dilute-impurity limit. Such behaviour departs from a monotonic evolution of vSm across the whole series, as well as from the expectation of its convergence to an integer value for x → 0. Our ARPES and XAS results, complemented by a phenomenological model, demonstrate an unconventional evolution of the MV character in the SmxLa1−xB6 series, paving the way to further theoretical and experimental considerations on the concept of MV itself, and its influence on the macroscopic properties of rare-earth compounds in the dilute-to-intermediate impurity regime. This study reveals a non-monotonic evolution of the mixed-valence character in the SmxLa1−xB6 series, with near-complete suppression of valence fluctuations in the intermediate substitution regime, followed by a re-emergent mixed-valence behavior in the dilute-impurity limit. [ABSTRACT FROM AUTHOR]

Lattice oxygen in metal oxides plays an important role in the reaction of diesel oxidation catalysts, but the atomic-level understanding of structural evolution during the catalytic process remains elusive. Here, we develop a Mn2O3/SmMn2O5 catalyst using a non-stoichiometric exsolution method to explore the roles of lattice oxygen in NO oxidation. The enhanced covalency of Mn–O bond and increased electron density at Mn3+ sites, induced by the interface between exsolved Mn2O3 and mullite, lead to the formation of highly active lattice oxygen adjacent to Mn3+ sites. Near-ambient pressure X-ray photoelectron and absorption spectroscopies show that the activated lattice oxygen enables reversible changes in Mn valence states and Mn-O bond covalency during redox cycles, reducing energy barriers for NO oxidation and promoting NO2 desorption via the cooperative Mars-van Krevelen mechanism. Therefore, the Mn2O3/SmMn2O5 exhibits higher NO oxidation activity and better resistance to hydrothermal aging compared to a commercial Pt/Al2O3 catalyst. This work reports on an exsolved Mn2O3/SmMn2O5 diesel oxidation catalyst competitive with current commercial materials in reactivity and hydrothermal aging resistance and further clarifies the catalytic mechanism for lattice oxygen as the reactive center [ABSTRACT FROM AUTHOR]

The current study employs both theoretical and experimental methods to investigate the effect of Ti and Co doping on the WO 3 nanocomposite with MoS 2 photoanode's photoelectrochemical (PEC) water-splitting reaction. A simple hydrothermal and sol-gel method was adopted for the preparation of samples. The Ti-doped WO 3 –MoS 2 (1.96 at %) sample showed the maximum optical absorption with a photocurrent density of 1.15 mA/cm2 at 1.6 V vs Ag/AgCl. The improvement in photocurrent density may be ascribed to the upward shifting of the conduction band edge towards the H+/H 2 redox potential as well as the presence of a large number of active sites in MoS 2. A high value of flat band potential of −0.3 V vs Ag/AgCl was achieved in Ti-doped WO 3 –MoS 2 , which was confirmed by Mott-Schottky measurements with the corresponding lowest charge transfer resistance at the semiconducting electrode/electrolyte interface. Furthermore, density functional theory calculations have also indicated that on doping WO 3 with Ti and Co, there is a slight upward shift in the conduction band minimum, without any significant change in the valence band maximum, with respect to the Fermi level. This study provides new insight into the impact of transition metal doping and nanocomposite of chalcogenide materials for WO 3 -based PEC electrodes. [Display omitted] • Ti and Co-doped WO 3 nanorods and MoS 2 nanoflowers were prepared using a cost-effective sol-gel and hydrothermal method. • MoS 2 plays a crucial role in boosting the PEC response due to the presence of a large number of active sites. • Improved charge carrier separation and enhanced PEC response were achieved in 1.96 at% Ti-doped WO 3 –MoS 2 sample. • DFT calculations showed that on doping WO 3 with Ti and Co, a slight upward shift in CBM, without any notable change in VBM, with respect to Fermi level. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT) presents promise as a cancer treatment method, but its efficacy faces challenges due to the inefficient Fenton catalytic reaction, where the transition metals' conversion from high to low valence states acts as the rate‐limiting step. Here, a strategy employing radioiodine is introduced to facilitate the valence conversion of transition metals for CDT enhancement. Iron‐based metal‐organic framework (MOF) nanoparticles (NPs) are synthesized labeled with radioiodine‐125 (125I), referred to as 125I‐MIL‐88B(Fe) NPs. These NPs possess a porous structure capable of concentrating and catalyzing H2O2 to generate highly toxic hydroxyl radicals (·OH). Furthermore, 125I can continuously produce hydrated electrons (eaq−) in aqueous environments, promoting the conversion of Fe3+/Fe2+ to boost ·OH production. In vitro and in vivo experiments validate the enhanced CDT effect on pancreatic cancer, driven by the reactive oxygen species (ROS)/mitogen‐activated protein kinase (MAPK)/p53 pathway‐mediated cell apoptosis. The radioiodine‐mediated electron‐supplying strategy not only amplifies the effectiveness of CDT but also unlocks new potential applications for radionuclides. [ABSTRACT FROM AUTHOR]

Considering the high cost and complicated recycling process of spent lithium-ion batteries (SLIBs), transforming SLIBs into environment functional materials may be a wise approach. Herein, lithium cobaltite (LCO) cathode powders recovered from SLIBs were used to activate peroxymonosulfate (PMS) for removing carbamazepine (CBZ). The recovered LCO enables a 98.2% removal efficiency of CBZ (2.5 mg/L) within 10 min, which was effective at a broader pH range (pH = 5.0–11.0). The influence of key factors (initial pH, PMS, and catalyst dosage) and coexisting substances (SO42−, H2PO4−, NO3−, Cl−, HCO3−, and HA) on CBZ degradation were examined in detail. The primary radical species during the degradation of CBZ were proved to be 1O2, SO4−, and.OH that generated from PMS activation initiated by the valence change of Co in recovered LCO. The recovered LCO displayed excellent reusability with about 80.0% removal of CBZ after six cycles. Homogeneous activation of PMS mainly contributed to CBZ degradation in the first run, but the recovered LCO catalyst dominated the heterogeneous activation of PMS for the degradation of CBZ in the second to sixth run. Finally, the CBZ degradation pathways were presented based on the identified intermediates. This research has offered a new strategy of "treating wastes with wastes" to maximize the recycling of electronic wastes to remove emerging pollutants. [ABSTRACT FROM AUTHOR]

Resistive random‐access memory (RRAM) stands out as a promising memory technology due to its ease of operation, high speed, affordability, exceptional stability, and potential to enable smaller memory devices with sizes under 10 nm. This has drawn significant attention, with atomic layer deposition (ALD) emerging as an ideal technology to tackle the challenges of nanoscale fabrication in the micro‐ and nanomanufacturing industry. ALD offers technological advantages such as functional multiple‐layer stacking, doping capabilities, and incorporating oxygen reservoirs or reactive layers. These factors contribute to achieving more intriguing, stable, and reliable nonvolatile resistance switching behaviors in RRAM. Specifically, ALD greatly benefits RRAM, that relies on the valence change mechanism, where high‐k transition metal oxides are commonly used as switching materials, and precise control over oxygen vacancies is achievable. This review provides a comprehensive overview of ALD films used in RRAM, delves into resistive switching properties and microscopic mechanisms in binary and ternary oxides and nitrides, and explores the impact of ALD‐prepared electrodes. Furthermore, the current status and future prospects of ALD‐based RRAM are highlighted, which is poised to catalyze further advancements in the fields of information storage and neural networks. [ABSTRACT FROM AUTHOR]

The current memory system is facing obstacles to improvement, and ReRAM is considered a powerful alternative. All‐inorganic α‐CsPbI3 perovskite‐based ReRAM working by electrochemical mechanism is reported, but the electrochemically active electrode raised difficulty in long‐term stable operation, and bulk α‐CsPbI3 device can not show resistive switching behavior with an inert metal top electrode. Herein, by making the α‐CsPbI3 into QDs and applying it to the device with inert Au as the top electrode, the devices working by valence change mechanism are successfully fabricated. The large surface‐to‐volume ratio made an abundant amount of iodine vacancies and facile migration of vacancies allowed the device to work by valence change mechanism. The devices show reliable electrical characteristics, 800 cycles endurance and retention for over 4 × 104 s, and air stability for 1 month. This work demonstrates that applying the QDs can improve the stability and enable a new type of working mechanism in ReRAM. [ABSTRACT FROM AUTHOR]

Generalization enables individuals to respond to novel stimuli based on previous experiences. The degree to which organisms respond is determined by their physical resemblance to the original conditioned stimulus (CS+), with a stronger response elicited by more similar stimuli, resulting in similarity-based generalization gradients. Recent research showed that cognitive or conceptual dimensions also result in gradients similar to those observed with manipulations of physical dimensions. Such findings suggest that attributes beyond physical similarity play a role in shaping generalization gradients. However, despite its adaptive relevance for survival, there is no study exploring the effectiveness of affective dimensions in shaping generalization gradients. In two experiments (135 Spanish and 150 English participants, respectively), we used an online predictive learning task, in which different stimuli (words and Gabor patches) were paired with the presence – or absence – of a fictitious shock. After training, we assessed whether valence (i.e., hedonic experience) conveyed by words shape generalization gradients. In Experiment 1, the outcome expectancy decreased monotonically with variations in valence of Spanish words, mirroring the gradient obtained with the physical dimension (line orientation). In Experiment 2, conducted with English words, a similar gradient was observed when non-trained (i.e., generalization) words varied along the valence dimension, but not when words were of neutral valence. The consistency of these findings across two different languages strengthens the reliability and validity of the affective dimension as a determinant of generalization gradients. Furthermore, our data highlight the importance of considering the role of affective features in generalization responses, advancing the interplay between emotion, language, and learning. [ABSTRACT FROM AUTHOR]

A multifunctional UIO-66-CoO x sonosensitizer, consisting of amorphous UIO-66 loaded with CoO x , is synthesized to simultaneously induce reactive oxygen species generation and GPX4 deactivation, achieving an augmented therapeutic effect via apoptosis-ferroptosis combination therapy. This work highlights the potential of amorphization engineering in enhancing the efficacy of MOF-based sonosensitizer for combined cancer treatments. [Display omitted] The development of efficient and multifunctional sonosensitizers is crucial for enhancing the efficacy of sonodynamic therapy (SDT). Herein, we have successfully constructed a CoO x -loaded amorphous metal-organic framework (MOF) UIO-66 (A-UIO-66-CoO x) sonosensitizer with excellent catalase (CAT)- and glutathione-oxidase (GSH-OXD)-like activities. The A-UIO-66-CoO x exhibits a 2.6-fold increase in singlet oxygen (1O 2) generation under ultrasound (US) exposure compared to crystalline UIO-66 sonosensitizer, which is attributed to its superior charge transfer efficiency and consistent oxygen (O 2) supply. Additionally, the A-UIO-66-CoO x composite reduces the expression of glutathione peroxidase (GPX4) by depleting glutathione (GSH) through Co3+ and Co2+ valence changes. The high levels of highly cytotoxic 1O 2 and deactivation of GPX4 can lead to lethal lipid peroxidation, resulting in concurrent apoptosis and ferroptosis. Both in vitro and vivo tumor models comprehensively confirmed the enhanced SDT antitumor effect using A-UIO-66-CoO x sonosensitizer. Overall, this study emphasizes the possibility of utilizing amorphization engineering to improve the effectiveness of MOFs-based sonosensitizers for combined cancer therapies. [ABSTRACT FROM AUTHOR]

To protect carbon/carbon composites against thermal corrosion and high-temperature oxidation, the thermal/oxygen barrier properties and static oxidation behavior of rare earth tantalates (YbTaO 4 and LuTaO 4) are investigated here. Both samples with the m ' phase are successfully fabricated. The formation of oxygen vacancies benefits from atomic substitution and valence variation and the widths of the domain boundaries (18–23 nm) are close to the phonon mean free path. Low thermal conductivity is caused by Umklapp phonon-phonon scattering, oxygen vacancies and domain walls, with LuTaO 4 having a value of 1.903 W m−1 K−1 at 900 °C. Furthermore, LuTaO 4 has decreased oxygen-ion conductivity due to a high activation energy and immobile vacancies. A LuTaO 4 /Si coating can efficiently prevent the oxidation of C/C composites at 1100 °C for 15 h. The coating failure results from oxygen penetrating along the microscopic cracks and mismatch of the thermal expansion coefficients. [ABSTRACT FROM AUTHOR]

Photocatalysis is a promising route to convert solar light into chemical energy for H 2 evolution and pollutants degradation. Hence, Ni 2 P decorated ZnCr 2 O 4 (Ni 2 P/ZnCr 2 O 4) nanofibers were prepared for boosting solar-light induced water splitting and tetracycline hydrochloride (TCH) degradation. For comparison to ZnCr 2 O 4 nanofibers, Ni 2 P/ZnCr 2 O 4 composites exhibited the better photocatalytic activities for water splitting and TCH removal. Owing to the co-catalytic effect of Ni 2 P for the efficient photon capture, the charge carriers were rapidly separated and migrated at the interface between Ni 2 P and oxygen-defected ZnCr 2 O 4. H 2 evolution rate of optimal C–Ni 2 P/ZnCr 2 O 4 with a nominal Ni 2 P content of 9.0 wt% was 575.89 μmol g−1 h−1, and its apparent quantum yield at 420 nm was 15.25 %, while its H 2 evolution decreased from 2815.13 to 2602.51 μmol g−1 after fifth cycle. In addition, the removal efficiency of C–Ni 2 P/ZnCr 2 O 4 was 93.68 % within 90 min, and declined to 88.76 % after five cycles for solar-light driven degradation of 50 mg L−1 TCH solution. The deactivation of C–Ni 2 P/ZnCr 2 O 4 was due to the photo-corrosion for the change in valence states of compositions. [ABSTRACT FROM AUTHOR]

Defect identification for unintentionally induced defects and radiation‐implemented defects always attracts great attention in semiconductor materials. Recent advances in carbon‐implemented single‐photon emitters in silicon urgently require the accurate identification of defect structures to reveal transition mechanisms. Using hybrid functional with finite size correction, we investigate the charge and optical transitions of carbon‐related defects, including CSiCSi, VSiCSi, CSi, SiiCSiCSi, and Ci. Except for Ci, other defects present the negative‐U feature in the charge transition process. CSiCSi and VSiCSi tend to perform p‐type conductivity with the electron capture transition close to the valence band, of which transition level ε (0/−1) is 0.30 eV for CSiCSi and ε (+1/−2) is 0.34 eV for VSiCSi. CSi and SiiCSiCSi present a bipolar doping character, and CSi tends to capture holes with transition ε (0/+2) = 0.10 eV. The optical transitions that typically emit or absorb light in the telecom optical wavelength bands are identified in these defects in terms of band edge recombination. The zero‐phonon lines of optical transitions of ε (+2/+1) for VSiCSi and Ci are consistent with a previous experiment involving single‐photon emitters. The findings are helpful to understand the performance degradation of silicon devices and provide a reference for identifying the structure of carbon‐related defects in silicon. [ABSTRACT FROM AUTHOR]

Cu‐based catalysts have been shown to selectively catalyze CO2 photoreduction to C2+ solar fuels. However, they still suffer from poor activity and low selectivity. Herein, we report a high‐performance carbon nitride supported Cu single‐atom catalyst featuring defected low‐coordination Cu‐N2 motif (Cu‐N2‐V). Lead many recently reported photocatalysts and its Cu‐N3 and Cu‐N4 counterparts, Cu‐N2‐V exhibits superior photocatalytic activity for CO2 reduction to ethanol and delivers 69.8 μmol g−1 h−1 ethanol production rate, 97.8 % electron‐based ethanol selectivity, and a yield of ~10 times higher than Cu‐N3 and Cu‐N4. Revealed by the extensive experimental investigation combined with DFT calculations, the superior photoactivity of Cu‐N2‐V stems from its defected Cu‐N2 configuration, in which the Cu sites are electron enriched and enhance electron delocalization. Importantly, Cu in Cu‐N2‐V exist in both Cu+ and Cu2+ valence states, although predominantly as Cu+. The Cu+ sites support the CO2 activation, while the co‐existence of Cu+/Cu2+ sites are highly conducive for strong *CO adsorption and subsequent *CO‐*CO dimerization enabling C−C coupling. Furthermore, the hollow microstructure of the catalyst also promotes light adsorption and charge separation efficiency. Collectively, these make Cu‐N2‐V an effective and high‐performance catalyst for the solar‐driven CO2 conversion to ethanol. This study also elucidates the C‐C coupling reaction path via *CO‐*CO to *COCOH and rate‐determining step, and reveals the valence state change of partial Cu species from Cu+ to Cu2+ in Cu‐N2‐V during CO2 photoreduction reaction. [ABSTRACT FROM AUTHOR]

To date, superconductivity in fullerides has been almost exclusively tuned by (chemical or physical) pressure control of the conduction bandwidth, W at half filling. This contrasts sharply with the extensive control of the superconducting transition temperature, T c in atom-based superconductors such as the cuprates and iron pnictides and chalcogenides via changes in valence (bandfilling). Here, we investigate the effect of doping away from the exactly half-filled C 6 0 3 − level in quaternary face-centered-cubic (fcc) — structured fulleride solids with nominal composition ( Rb 2. 5 − x Csx) Ba 0. 5 C 6 0 (0 ≤ x ≤ 2. 5), in which divalent Ba 2 + ions partially replace monovalent alkali Rb + / Cs + ions. The resulting charged-modified fullerides in which the t 1 u bandwidth is also varied with changing x show a dome-shaped dependence of T c on interfullerene separation in analogy with their half-filled antecedents. However, following electron injection beyond half-filling, the superconductivity dome is found to shift towards shorter interfullerene separations, i.e. towards increased conduction bandwidths. [ABSTRACT FROM AUTHOR]

Surface templating by electrostatic surface potentials is the least invasive way to design large-scale artificial nanostructures. However, generating sufficiently large potential gradients remains challenging. Here, we lay the groundwork for significantly enhancing local electrostatic fields by chemical modification of the surface. We consider the hexagonal boron nitride (h-BN) nanomesh on Rh(111), which already exhibits small surface potential gradients between its pore and wire regions. Using photoemission spectroscopy, we show that adding Au atoms to the Rh(111) surface layer leads to a local migration of Au atoms below the wire regions of the nanomesh. This significantly increases the local work function difference between the pore and wire regions that can be quantified experimentally by the changes in the h-BN valence band structure. Using density functional theory, we identify an electron transfer from Rh to Au as the microscopic origin for the local enhancement of potential gradients within the h-BN nanomesh. [ABSTRACT FROM AUTHOR]

Controlling nanoscale tip‐induced material removal is crucial for achieving atomic‐level precision in tomographic sensing with atomic force microscopy (AFM). While advances have enabled volumetric probing of conductive features with nanometer accuracy in solid‐state devices, materials, and photovoltaics, limitations in spatial resolution and volumetric sensitivity persist. This work identifies and addresses in‐plane and vertical tip‐sample junction leakage as sources of parasitic contrast in tomographic AFM, hindering real‐space 3D reconstructions. Novel strategies are proposed to overcome these limitations. First, the contrast mechanisms analyzing nanosized conductive features are explored when confining current collection purely to in‐plane transport, thus allowing reconstruction with a reduction in the overestimation of the lateral dimensions. Furthermore, an adaptive tip‐sample biasing scheme is demonstrated for the mitigation of a class of artefacts induced by the high electric field inside the thin oxide when volumetrically reduced. This significantly enhances vertical sensitivity by approaching the intrinsic limits set by quantum tunneling processes, allowing detailed depth analysis in thin dielectrics. The effectiveness of these methods is showcased in tomographic reconstructions of conductive filaments in valence change memory, highlighting the potential for application in nanoelectronics devices and bulk materials and unlocking new limits for tomographic AFM. [ABSTRACT FROM AUTHOR]

To generate red emissions, manganese (IV) ions have recently gained recognition as potent non-rare-earth activators. However, the oxide and fluoride hosts that offer suitable environments for Mn4+ require careful preparation, involving precise control of reaction parameters like redox equilibrium and temperature. In the current work, we show simultaneous oxidation of Mn2+ to Mn4+ by devitrification of glassy Na 2 Ge 4 O 9 : Mn under moderate atmospheric conditions and under the argon atmosphere. The G-sample was devitrified via thermal treatment after the parent glass, which shares the same chemical formula as dilithium tetragermanate (Na 2 Ge 4 O 9), was created through the use of traditional melt-quenching (MQ). Optical spectroscopy and electron paramagnetic resonance (EPR) spectroscopic are utilized to confirm the Mn2+ oxidation to Mn4+ from glass stat to glass ceramic after thermal treatment. Due to the transition from Mn2+ to Mn4+, a sharp 668 nm emission peak is recorded whereas the red emission peaking at 611 nm monitored in glass is steadily reduced. The temperature-dependent PL spectra of the Na 2 Ge 4 O 9 :0.1Mn+4, red-emitting GC in the temperature range ∼295–490 K were recorded. The PL emission intensity decreases gradually with increasing the temperature. The technique showcased for producing Na 2 Ge 4 O 9 :Mn4+ phosphors could be expanded to synthesize other phosphors incorporating activators possessing a high oxidation state. [ABSTRACT FROM AUTHOR]

The unintentional incorporation of various unknown trace amounts of impurities poses challenges and controversies in identifying luminescent mechanisms of certain systems. A common approach to confirm or exclude the involvement of a certain activation center is to monitor the changes in luminescence by intentionally doping the inferred species into the crystal. Here, an intriguing luminescent phenomenon resulting from the hidden interplay between the dopants and trace impurities, is presented. In alkaline‐earth stannate perovskites, near‐infrared luminescence is observed. By combining density‐functional calculations with the well‐designed doping and codoping experimental strategies, the mechanisms behind this anomaly is successfully uncovered. It originates from the stabilization of Cr3 + by codopants such as Bi and rare‐earth (RE) ions, acting as electron donors. The luminescence is almost unobservable when chromium is doped alone, and thus the traditional identification method does't work. This work emphasizes the important role of trace impurity in materials, especially the subtle change of valence state of trace impurity upon doping, which provides enlightening insights and prompts reassessments of numerous reported anomalous luminescent phenomena. [ABSTRACT FROM AUTHOR]

Cathode materials with conversion mechanisms for aqueous zinc-ion batteries (AZIBs) have shown a great potential as next-generation energy storage materials due to their high discharge capacity and high energy density. However, improving their cycling stability has been the biggest challenge plaguing researchers. In this study, CuO microspheres were prepared using a simple hydrothermal reaction, and the morphology and crystallinity of the samples were modulated by controlling the hydrothermal reaction time. The as-synthesized materials were used as cathode materials for AZIBs. The electrochemical experiments showed that the CuO-4h sample, undergoing a hydrothermal reaction for 4 h, had the longest lifecycle and the best rate of capability. A discharge capacity of 131.7 mAh g−1 was still available after 700 cycles at a current density of 500 mA g−1. At a high current density of 1.5 A g−1, the maintained capacity of the cell is 85.4 mA h g−1. The structural evolutions and valence changes in the CuO-4h cathode material were carefully explored by using ex situ XRD and ex situ XPS. CuO was reduced to Cu2O and Cu after the initial discharge, and Cu was oxidized to Cu2O instead of CuO during subsequent charging processes. We believe that these findings could introduce a novel approach to exploring high-performance cathode materials for AZIBs. [ABSTRACT FROM AUTHOR]

The development of high-performance direct-Z Scheme heterojunctions as photocatalysts is the focus of current research, and it is also an effective way to improve the performance of photocatalysts. Based on this, we use density functional theory (DFT) to predict two-dimensional (2D) XSe2/SiH (X = Zr, Sn) van der Waals (vdW) heterojunction as a potential direct Z-scheme heterojunction photocatalyst. The results indicate that both heterojunctions exhibit a typical Type-II band edge arrangement. Furthermore, the small band gap and built-in electric field of the heterojunctions facilitate electronic transitions between the valence band (VB) and conduction band (CB), thereby increasing the probability of interlayer electron–hole (e−-h+) recombination within the heterojunction. This process is beneficial for the formation of direct-Z Scheme heterojunctions. In addition, the XSe2/SiH (X = Zr, Sn) heterojunction exhibits remarkable photogenerated electron and hole driving forces, along with exceptional light-trapping capabilities. Therefore, XSe2/SiH (X = Zr, Sn) heterojunction is a potential new photocatalyst. [ABSTRACT FROM AUTHOR]

Proton‐based energy storage systems provide a more sustainable alternative for large‐scale energy storage applications. However, conventional proton batteries/pseudocapacitors suffer from severe capacity loss because of reduced ionic conductivity and water‐to‐ice conversion at ultralow temperatures. Here, anti‐freezing proton‐rich electrolytes with ultralow freezing point (below −80 °C) and high conductivity (7.89 mS cm−1 at −80 °C) are developed, combined with open framework‐structured Prussian blue analogous (VHCF) electrodes with proton‐rich binding sites, to construct a promising proton pseudocapacitor at ultralow temperatures. Hydrogen bond‐induced solvated structures and physicochemical properties are clarified by comprehensive characterization techniques and computational simulations. Temperature‐dependent structure and valence changes for VHCF electrodes at low temperatures are revealed, where the multi‐electron transfer reaction is affected by temperature to limit the capacity output. The proton pseudocapacitor (VHCF//6 m H2SO4//MoO3‐x) achieves excellent electrochemical performance in the temperature range from −80 to 25 °C, and delivers a voltage window of 0 to 2.8 V and a high energy density of 74.9 Wh kg−1 at −80 °C. This proton‐rich electrolyte‐electrode design principle suggests an effective strategy enabling next‐generation energy technology under extreme conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-doped cerium-based adsorbents exhibited better Cr(VI) adsorption advantages than pure cerium material. • Fe doping promoted the formation of Ce(III) in cerium-based adsorbents. • Fe doping contributed to the formation of oxygen vacancy in cerium-based adsorbents. • Fe doping facilitated the valence transition of Ce(IV)/Ce(III) in Cr(VI) adsorption. • DFT calculation result revealed that Fe doping accelerated the electron transfer in Cr(VI) reduction. Cerium-based adsorbents possessed unique advantages of valence variability and abundant oxygen vacancies in hexavalent chromium (Cr(VI)) adsorption, but high cost and unstable properties restricted their application in Cr(VI) contained wastewater treatment. Herein, a series of bimetallic adsorbents with different cerium/iron ratios (CeFe@C) were prepared by adding inexpensive Fe into Ce-based adsorbents (Ce@C), and the effect of Fe doping on adsorption properties of Ce@C for Cr(VI) was investigated thoroughly. Compared with pristine Ce@C, CeFe@C exhibited excellent removal performance for Cr(VI), and the improved maximum adsorption capacity reached 75.11 mg/g at 25℃. Benefiting from Fe doping, CeFe@C had good regeneration property, with only 25 % decrease after five adsorption–desorption cycles. Contents of trivalent cerium (Ce(III)) and oxygen vacancies (O v) in bimetallic adsorbents were positively correlated with divalent iron (Fe(II)) doping, indicating that the formation of Ce(III) and surface defects on Ce@C could be effectively regulated by Fe doping. Density functional theory (DFT) calculation results further proved that the doped Fe enhanced the electron transfer effectively and lowered the energy barriers of Cr(VI) adsorption onto Ce@C surface, strengthening the reduction and complexation to Cr(VI). This study provides new insights for improving the Cr(VI) removal performance by modified Ce-based adsorbents, and further promotes the utilization potentiality of low-cost and low-toxicity Ce-based adsorbents in Cr(VI)-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, the novelly designed Sr 0.5 Zr 2 (PO 4) 3 –Ce 0.5 Sm 0.5 PO 4 composite ceramics were utilized as nuclear waste form to simultaneously immobilize simulated fission products Sr and actinide nuclides. The phase transition mechanism, thermokinetics and densification behavior of Sr 0.5 Zr 2 (PO 4) 3 –Ce 0.5 Sm 0.5 PO 4 composite ceramics based on in-situ synthesis were systemically analyzed by XRD, in-situ XPS, TG-DSC, SEM and density measurements. The results demonstrate that the formation of Ce 0.5 Sm 0.5 PO 4 solid solution phase preceded that of Sr 0.5 Zr 2 (PO 4) 3 phase, of which there is a valence change of Ce from Ce4+ to Ce3+ before 1023 K. Additionally, as for the exothermic crystallization enthalpy, change of exothermic crystallization enthalpy and activation energy, the values of Sr 0.5 Zr 2 (PO 4) 3 and Ce 0.5 Sm 0.5 PO 4 phases in composite ceramics are 286.17 – 515.61 mJ, 19.11 – 35.38 J/g, 702.45 kJ/mol and 145.21 – 232.44 mJ, 9.26 – 15.44 J/g, 450.04 kJ/mol, respectively. It is then indicated that the formation of Ce 0.5 Sm 0.5 PO 4 phase is definitely more favorable than that of Sr 0.5 Zr 2 (PO 4) 3 phase. Simultaneously, the relative densities of Sr 0.5 Zr 2 (PO 4) 3 –Ce 0.5 Sm 0.5 PO 4 composite ceramics are more than 95 % when the sintering temperature exceeds 1273 K. [ABSTRACT FROM AUTHOR]

Introduction: Models of attachment and information processing suggest that the attention infants allocate to social information might occur in a schemadriven processing manner according to their attachment pattern. A major source of social information for infants consists of facial expressions of emotion. We tested for differences in attention to facial expressions and emotional discrimination between infants classified as securely attached (B), insecureavoidant (A), and insecure-resistant (C). Methods: Sixty-one 14-month-old infants participated in the Strange Situation Procedure and an experimental task of Visual Habituation and Visual Paired-Comparison Task (VPC). In the Habituation phase, a Low-Arousal Happy face (habituation face) was presented followed by a VPC task of 6 trials composed of two contrasting emotional faces always involving the same actress: the one used in habituation (trial old face) and a new one (trial new face) portraying changes in valence (Low-Arousal Angry face), arousal (High-Arousal Happy face), or valence + arousal (High-Arousal Angry face). Measures of fixation time (FT) and number of fixations (FC) were obtained for the habituation face, the trial old face, the trial new face, and the difference between the trial old face and the trial new face using an eye-tracking system. Results: We found a higher FT and FC for the trial new face when compared with the trial old face, regardless of the emotional condition (valence, arousal, valence + arousal contrasts), suggesting that 14-month-old infants were able to discriminate different emotional faces. However, this effect differed according to attachment pattern: resistant-attached infants (C) had significantly higher FT and FC for the new face than patterns B and A, indicating they may remain hypervigilant toward emotional change. On the contrary, avoidant infants (A) revealed significantly longer looking times to the trial old face, suggesting overall avoidance of novel expressions and thus less sensitivity to emotional change. Discussion: Overall, these findings corroborate that attachment is associated with infants' social information processing. [ABSTRACT FROM AUTHOR]

Transition‐metal Mn2+ ion‐doped transparent ceramics (TCs) are promising color‐convertors to improve color rendition for solid‐state lighting. However, the stabilization of Mn2+ remains a challenge owing to the changeable atmosphere in the specific preparation of TC. In this work, the variations of valence states of Mn ions in typical garnet lattice host (YAG and LuAG) throughout the TC fabrication were demonstrated. By combined first principles calculation and experimental investigation, an enhanced self‐reduction of Mn ions was clarified in LuAG host, which was originated from the higher concentration of oxygen vacancy defects. Moreover, the air annealing treatment could significantly weaken and enhance the absorption of Mn2+ and Mn3+ respectively, degrading the orange–red emission peaking at 594 nm. On account of the oxidation of Mn2+ ions, a photoluminescence spectra redshift of 9 nm was observed with increasing air annealing temperature and oxygen content, owing to strengthened crystal field strength surrounding Mn2+ ions. Finally, a high color rendering index of 74.5 of resultant white laser diodes device structured by single‐phase LuAG:Ce,Mn TCs was obtained based on an efficient energy transfer process from Ce3+ to Mn2+. This study will deepen the understanding of the crystal defects inside TCs on luminescence properties, as well as inspiring more exploration on defect control to develop high performance ceramic color‐convertor. [ABSTRACT FROM AUTHOR]

Multiferroic composites of (1 − x)BaTi0.98Ni0.02O3–(x)CoFe2O4 (0 ≤ x ≤ 0.06) were prepared through conventional solid‐state reaction route. X‐ray diffraction (XRD) studies along with the Rietveld refinement endorse the multiphase nature of the nanocomposite samples. The XRD peaks of the tetragonal bare barium titanate and the inverse cubic spinel of cobalt ferrite nanostructures phase can be identified separately. The tetragonality ratio of the bare barium titanate drops with the addition of the guest material, i.e., cobalt ferrite in the ferroelectric matrix. The Fourier transform infrared (FTIR) spectra confirm the main absorption bands near 540–560 cm−1, corresponding to the metal‐oxide absorption band (ν1 mode), and are related to the stretching modes of the Ti–O bonds. The Raman spectra also signify the two symmetries confirming the nanocomposites' ferroelectric and ferromagnetic phases. The surface morphology studies reveal the hexagonal and spherical shape of the grains in the nanostructures and nanocomposites. The energy‐dispersive x‐ray spectroscopy (EDX) spectra confirm the presence of all the elements in the samples. The ferroelectricity in the nanocomposite drops due to fluctuations in the valence state of Fe2+/Fe3+ that enhances the leakage current of the nanocomposites. The magnetic moment and dielectric constant of the nanocomposites are enhanced as the guest compound CoFe2O4 is added to the bare BaTi0.98Ni0.02O3. Thus, the simultaneous coexistence of ferroelectric and magnetic ordering at room temperature confirms the multiferroic behavior of the nanostructure and the nanocomposites. [ABSTRACT FROM AUTHOR]

NiFe-based electrocatalysts will experience dynamical surface reconstruction during oxygen evolution reaction (OER) process, and the derived metal (oxy)hydroxide hybrids on the surface have been considered as the actual active species for OER. Tremendous efforts have been dedicated to understanding the surface reconstruction, but there is rare research on recognizing the origin of improved performance derived from anion species of substrate. Herein, the OER electrocatalytic characteristics were tuned with different anions in NiFe-based catalyst, using NiFe-based oxides/nitride/sulfide/selenides/phosphides (NiFeX, X = O, N, S, Se, and P) as the model materials. The combination of X-ray photoelectronic spectroscopy, electrochemical tests, operando spectroscopic characterizations, and density functional theory (DFT) calculations, reveals that anion with lower electronegativity in NiFe-based catalyst leads to higher conductivity and delayed valence transition of Ni sites, as well as optimized adsorption behavior towards oxygen intermediates, contributing to enhanced OER performance. Accordingly, NiFeP electrocatalyst demonstrates an ultralow overpotential of 265 mV at 20 mA·cm−2 for OER, as well as long-term stability. This work not only offers further insights into the effect of anionic electronegativity on the intrinsic OER electrocatalytic properties of NiFe-based electrocatalyst but also provides guide to design efficient non-noble metal-based electrocatalysts for water oxidation. [ABSTRACT FROM AUTHOR]

This study effectively addresses the rapid deactivation of manganese-based catalysts in humid environments during ozone decomposition by introducing iron-doped manganese oxide octahedral molecular sieve (Fe-OMS-2) catalysts supported on activated carbon (AC). By optimizing the doping ratio of Fe-OMS-2, the Fe-OMS-20.5/AC catalyst achieves nearly 100% ozone decomposition efficiency across a wide range of relative humidity levels (0 to 60%), even at elevated air flow rates of 800 L·g−1·h−1, outperforming standalone AC, Fe-OMS-2, or a simple mixture of OMS-2 and AC. The Fe-OMS-20.5/AC catalyst features a porous surface and a mesoporous structure, providing a substantial specific surface area that facilitates the uniform distribution of the Fe-OMS-2 active phase on the AC surface. The incorporation of Fe3+ ions enhances electron transfer between valence state transitions of Mn, thereby improving the catalyst's efficiency in ozone decomposition. Additionally, the AC component protects catalytic sites and enhances the catalyst's humidity resistance. In conclusion, this research presents a novel strategy for developing highly efficient and cost-effective ozone decomposition catalysts that enhance dehumidification, significantly contributing to industrial ozone treatment technologies and advancing environmental protection. [ABSTRACT FROM AUTHOR]

To study the metal ion chelating agent (DL‐malic acid) inhibiting oxidation characteristics of residual coal in goaf, the microscopic thermal transformation characteristics of the treated coal samples were obtained using apparent morphology, infrared spectroscopy, free radical testing, and thermal analysis. The results demonstrate that after the addition of malic acid, the sphericity and roundness of the coal samples decrease, and the small fractured particles accumulate in the pores of the oxidized coal samples and, thereby, reduce the number of coal–oxygen contact sites. The addition of 10% malic acid promotes the conversion of functional groups (FG) and free radicals in pre‐oxidized coal, inhibits the catalytic effect of metal ions, generates more active sites, and increases the total heat release during the combustion process. There are strong endothermic points in the malic acid‐treated coal samples, and the free water evaporation blocked by small particles in the holes delays the initial heat release temperature of the coal samples. Pre‐oxidation can promote changes in the valence state of metal ions in coal, increase the adhesion between broken pre‐oxidized coal particles via malic acid chelation, and lose the catalytic effect of metal ions; this inhibits the process of oxidative re‐ignition of coal samples. [ABSTRACT FROM AUTHOR]

Ussingite (Na2AlSi3O8OH) is a mineral with a unique interrupted framework structure and strong hydrogen bonding. It contains 4-, 6-, and 8-membered tetrahedral rings resembling feldspars, but, unlike the latter, is partially depolymerized. There are four crystallographically distinct tetrahedral (T) sites, two of which (T1, T2) are Q4 [i.e., having 4 next nearest neighbor (NNN) T sites], and the other two (T3, T4) are Q3 (i.e., having 3 NNN T sites), each with NNN (in brackets) of T1(1T2, 1T3, 2T4), T2(1T1, 2T3, 1T4), T3(1T1, 2T2), and T4(2T1, 1T2). There is one unique OH site in the T4-O8-H···O2-T3 configuration, where O8 and O2 are nonbridging O atoms (NBO). In the ordered structure, T1 is fully occupied by Al, and the other three T sites by Si. Previous X-ray and neutron diffraction and 1H and 29Si NMR studies gave contradictory conclusions regarding Si-Al disorder. In this study, we were able to unambiguously clarify the issue via comprehensive one- and two-dimensional 1H, 29Si, 27Al, and 23Na NMR and first-principles calculation. It was revealed that there is ~3% Si-Al disorder that occurs between neighboring T1-(O)-T2 sites, such that the formation of Al-O-Al linkage and Al(Q3) are avoided. The disorder was found to result in the development of Si(Q3) sites with various NNN, including 3Al and 3Si, and neighboring OH sites having significantly shorter and longer hydrogen-bonding distances than in the ordered structure, with 1H chemical shifts near 15~16 ppm and 11 ppm, in addition to a main peak near 13.9 ppm. Good correlation was found between 1H chemical shift, hydrogen-bonding (O-H, H···O, and O···O) distances, and Si-O distances in the Si-O-H···O-Si linkage. This suggests that Si-Al disorder is correlated with variation in hydrogen-bonding distances via through-bond transmission of bond valence variations. This could be a universal phenomenon also applicable to other hydrous minerals. The revelation of preferential partition of Al in Q4 over Q3 sites to avoid the formation of Al-OH and Al-NBO provides insight into their behavior in other partially depolymerized hydrous aluminosilicate systems, such as glasses and melts. [ABSTRACT FROM AUTHOR]

Single atom catalysts (SACs) play a crucial role in energy catalysis due to their distinct coordination environment and high atomic utilization efficiency. This study focuses on the synthesis of a monatomic Cu catalyst with Cu-N1C1 coordination anchored to N-doped Ti3C2Tx MXene (Cu SA@N-Ti3C2Tx) to achieve efficient reduction of CO2 to CO. Detailed characterization, including morphology and multispectral analysis, confirmed the uniform distribution of asymmetrically coordinated Cu atoms in unsaturated C-Cu-N bridge fragments on Ti3C2Tx. The Cu SA@N-Ti3C2Tx catalyst exhibited an excellent CO selectivity with Faraday efficiency of 97.4% at −0.58 V vs. reversible hydrogen electrode (RHE) and satisfactory durability. The in situ X-ray absorption fine structure (XAFS) results confirmed that the carbon dioxide reduction reaction (CO2RR) product distribution is mainly affected by potential-dependent valence change of Cu species. These findings highlight the extensive potential of tuning coordination structure of MXene-based single-atom catalysts for CO2 reduction reactions. [ABSTRACT FROM AUTHOR]

The present paper deals with a new two-in-one zero-dimensional (0D) organic–inorganic hybrid compound namely (C6H10N2)4[CdBr6][CdBr4]2. This molecular crystal structure contains isolated CdBr4 tetrahedra and CdBr6 octahedra. The optical characterization by UV–Vis–NIR spectroscopy shows that the (C6H10N2)4[CdBr6][CdBr4]2 exhibits a large gap energy of 4.97 eV. Under UV excitation, this hybrid material shows a bright cold white light emission (WLE) at room temperature. The photoluminescence (PL) analysis suggests that the WLE originates from the organic molecules. Density of states (DOS) analysis using the density functional theory (DFT) demonstrates that the calculated HOMO(Br)→LUMO(organic) absorption transition (4.1 eV) does not have significant intensity, while, the transition involving the valence band (VB) and the second and third conduction bands (CB) around 5 eV are allowed, which is in good agreement with the experimental gap value. The interesting theoretical result is that the LUMO(organic)→HOMO(Br) emission is allowed, which confirms the important role of the organic molecule in the emission mechanism, in good agreement with the experimental PL analysis. [ABSTRACT FROM AUTHOR]

A catalyst consisting of Cu0.5Mg0.5Fe2O4 (CMF) supported on carbon nanotubes (CNTs) which exhibits great potential as an adsorbent for treating Cr(VI)‐contaminated wastewater has been successfully prepared. The ferrite possesses excellent magnetic properties, while CNTs have the advantage of a large surface area. This composite material not only prevents the aggregation of magnetic materials and enhances the exposure of active sites but also effectively solves the recycling problem of CNTs. Our results show that the adsorption capacity of Cu0.5Mg0.5Fe2O4–carbon nanotubes (CMF‐CNTs) for Cr(VI) wastewater (45.60 mg/g) is 1.49 times higher than that of Cu0.5Mg0.5Fe2O4 (30.48 mg/g). Compared to a single catalyst, CMF‐CNTs not only improve the dispersibility of magnetic materials but also exhibit synergistic effects between the composite materials, enhancing the chemical adsorption capacity. After five consecutive adsorption and desorption experiments, the adsorption capacity of CMF‐CNTs remains at 88% of its initial value. Furthermore, the study of the catalyst before and after adsorption by XPS reveals that the valence state transition of Fe3+/Fe2+ and Cu2+/Cu+ plays a crucial role in the adsorption process. The results of this study demonstrate the potential of using waste materials for effective wastewater treatment and provide insights into the development of new adsorbents for pollutant removal. [ABSTRACT FROM AUTHOR]

In recent years, organic–inorganic hybrid perovskite materials have garnered extensive attention from scholars. Given its high absorption coefficient, carrier mobility, and diffusion length, it is widely studied for applications in various optoelectronic devices, such as solar cells, photodetectors, field-effect transistors, and light emitting diodes. Among them, the interfacial charge transfer process is a key factor influencing the performance of devices using perovskite materials. The charge transfer (CT) at the interface is typically detected via Raman spectroscopy. There are three types of related CT processes, namely, the interfacial ground state charge transfer, the photoinduced charge transfer resonance, and the electronic excitation resonance within the molecule itself. Among these factors, electronic excitation resonance manifests as an exciton resonance within the perovskite structure, providing energy for nearby charge transfer, thereby promoting charge transfer and enhancing Raman signals. Therefore, enhancing exciton resonance within the perovskite structure plays a crucial role in optoelectronic devices. This paper aimed to study the mechanism of oxygen plasma passivation of interstitial iodine defects and its enhancement effect on the Raman of perovskite substrates. Typically, interstitial iodine defects induce electron–hole recombination. In the process of oxygen plasma treatment, interstitial iodine is converted into pentavalent iodine, which can effectively fill related defects, inhibit electron–hole recombination, and prolong exciton lifetime, thereby promoting charge transfer and enhancing Raman intensity. [ABSTRACT FROM AUTHOR]

A mononuclear valence tautomeric (VT) complex, [Co(pycz)2(Sq)(Cat)] (1‐trans), where pycz = 9‐(pyridin‐4‐yl)‐9H‐carbazole, Sq⋅− = 3,5‐di‐tert‐butyl‐semiquinonato, and Cat2− = 3,5‐di‐tert‐butyl‐catecholato, is synthesized in the trans configuration, which undergoes one‐step valence tautomeric transition above room temperature. Remarkably, 1‐trans can transform into its isomeric structure, [Co(pycz)2(Sq)(Sq)] (1‐cis), at temperature above 350 K in a single‐crystal‐to‐single‐crystal way by in situ molecular twist, and the resulting 1‐cis exhibits a pronounced two‐step VT transition during magnetic measurements that is rare for mononuclear VT complexes. Such drastic solid‐state structural transformation is reported in VT compounds for the first time, which is actuated by a crystal surface's melting‐recrystallization induced phase transition process. DFT calculations offer an underlying mechanism suggesting a concerted bond rotation during the structural transformation. The results demonstrate an unconventional approach that realizes structural transformation of VT complexes and the control of VT performance. [ABSTRACT FROM AUTHOR]

Resistive switching devices based on metal oxides are candidates for nonvolatile memory storage. They often rely on the valence change mechanism, the field‐induced movement of donor ions leading to nanoscale conductive paths in filamentary‐type devices. Devices usually consist of a transition metal oxide like Ta2O5 sandwiched between two metal electrodes. Critical parameters of the devices, such as cycle‐to‐cycle variability, Roff/Ron ratio, and endurance depend on the morphology and composition of the filaments. However, investigating filaments on the nanoscale is cumbersome, and commonly applied techniques such as conductive atomic force or transmission electron microscopy require delaminating the metal top electrode, inhibiting in operando investigations over many switching cycles. Here, the authors use infrared scattering‐type scanning near‐field optical microscopy (s‐SNOM) to investigate resistive switching in Ta2O5 films with a graphene top electrode in operando and reveal individual filaments on the device level. By selecting an appropriate illumination frequency, the authors can trace the evolution of filaments and the joule heating‐induced retraction of the top electrode until device failure. s‐SNOM promises a deeper understanding of resistive switching devices' microscopic switching behavior and applies to a wide range of resistive switching oxides, such as HfO2, SrTiO3, and SiO2. [ABSTRACT FROM AUTHOR]

[Display omitted] Valence modulation of transition metal oxides represents a highly effective approach in designing high-performance catalysts, particularly for pivotal applications such as the hydrogen evolution reaction (HER) in solar/electric water splitting and the hydrogen economy. Recently, there has been a growing interest in high-valence transition metal-based electrocatalysts (HVTMs) due to their demonstrated superiority in HER performance, attributed to the fundamental dynamics of charge transfer and the evolution of intermediates. Nevertheless, the synthesis of HVTMs encounters considerable thermodynamic barriers, which presents challenges in their preparation. Moreover, the underlying mechanism responsible for the enhancement in HVTMs still needs to be discovered. Hence, the universal synthesis strategies of the HVTMs are discussed, and direct Raman spectroscopic evidence for intermediates regulation is revealed to guide the further design of the HVTM electrocatalysts. This work offers new insights for facile designing of HVTMs electrocatalysts for energy conversion and storage through adjusting the reaction pathway. [ABSTRACT FROM AUTHOR]

The ultrafast high peak powers of femtosecond laser ablation can be used to safely process explosives by precisely controlling the laser energy and focus. The laser absorption mechanisms and capacities are wavelength dependent due to the different compositions and structures of explosives. The absorption characteristics directly affect the efficiency and safety of femtosecond laser processing. Therefore, the optical absorption mechanisms and characteristics of five typical explosives excited by femtosecond lasers at different wavelengths have been studied. Absorption spectra of β-phase octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (β-HMX), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), cyclotrimethylenetrinitramine (RDX), pentaerythritol tetranitrate (PETN) and 2,4,6-trinitrotoluene (TNT) were obtained by quantum chemistry calculation. With infrared (IR) lasers, explosives absorb energy mainly via vibrational excitation in functional groups, which subsequently leads to bond breaking. Calculations indicated that the absorption maxima attributed to vibrations in these explosives were all concentrated between 3125 and 3571 nm. Ultraviolet–visible (UV–vis) lasers could be used to excite the explosives via valence electron transitions, which could trigger chemical reactions. β-HMX, RDX and PETN had narrow absorption spectra with strong peaks concentrated around 170–225 nm, while TATB and TNT had broad absorption ranges with strong peaks around 230–300 nm. These bands were far from the widely used 810 nm near-infrared femtosecond laser. [ABSTRACT FROM AUTHOR]

In this paper, (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 (x = 0, 0.06, 0.08, and 0.10) ceramic coatings were prepared by supersonic plasma spraying. Phase structure, microstructure, dielectric, ferroelectric, and piezoelectric properties of the (Bi 0.5 Na 0.5)TiO 3 ceramic coatings doped with BaTiO 3 were all thoroughly examined. According to the findings, all of the (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 ceramic coatings have a typical perovskite structure and form a morphotropic phase boundary (MPB) with rhombohedral and tetragonal phases coexisting in the x = 0.06–0.10 range. The coating's overall surface is uniformly flat, with a surface roughness (Sa) of less than 10 μm and a line roughness (Ra) of less than 2 μm. The coating has a homogeneous cross section, a well-integrated interface, a few pores and cracks, and a porosity of less than 6 %. With no obvious valence changes of the other elements, the results of XPS indicate a certain degree of breakdown during the spraying process, when Ti4+ changes to generate oxygen vacancy defects of Ti3+. The best electrical conductivity of the 0.92BNT-0.08BT coating has been found at x = 0.08, where the dielectric constant is 255 (0.02), the remnant polarization (P r) is 22.21 μC/cm2, the coercive field (E c) is 29.17 kV/cm, and the piezoelectric coefficient (d 33) is 35.1 pC/N. The (1- x)(Bi 0.5 Na 0.5)TiO 3 - x BaTiO 3 ceramic coating application space and range at high temperature are expanded when the temperature (T m) close to the maximum dielectric constant increases significantly reaching 431.2 °C. [ABSTRACT FROM AUTHOR]

TiN/Ti/HfO2/Pt resistive switching devices have been fabricated, measured, and modeled. After programming the devices in the low resistance state, the current–voltage characteristic below the reset switching voltage was measured at different temperatures (from 90 to 350 K). A weak but complex temperature dependence was obtained for several voltage regimes. These memristors belong to a wider set known as valence change memories, whose conductance is determined by the formation of conductive filaments (CFs) linked to a high density of oxygen vacancies in a dielectric sandwiched between two metal electrodes. This usually leads to ohmic conduction in the low resistance state. However, a non-linear current dependence has been also observed in the measured devices, in addition to symmetric current–voltage curves for positive and negative biases in the 0–0.6 V voltage range. Three different thermal dependences have been considered for explaining the whole set of experimental data. Two of them are linked to ohmic filamentary conduction; the CF shows a conductivity enhancement due to thermally activated mechanisms at low temperatures; on the contrary, a CF conductivity degradation is observed at the higher temperatures. Finally, an additional slightly higher value for the non-linear current component as the temperature rises has also been taken into account. A semiempirical compact model has been implemented including these conduction mechanisms and their corresponding temperature dependences, the device has been simulated in LT-Spice and the experimental currents have been correctly reproduced. [ABSTRACT FROM AUTHOR]

We report the implementation of effective quantum electrodynamics (QED) potentials for all-electron four-component relativistic molecular calculations using the DIRAC code. The potentials are also available for two-component calculations, being properly picture-change transformed. The latter point is important; we demonstrate through atomic calculations that picture-change errors are sizable. Specifically, we have implemented the Uehling potential [E. A. Uehling, Phys. Rev. 48, 55 (1935)] for vacuum polarization and two effective potentials [P. Pyykkö and L.-B. Zhao, J. Phys. B: At., Mol. Opt. Phys. 36, 1469 (2003) and V. V. Flambaum and J. S. M. Ginges, Phys. Rev. A 72, 052115 (2005)] for electron self-energy. We provide extensive theoretical background for these potentials, hopefully reaching an audience beyond QED specialists. We report the following sample applications: (i) We first confirm the conjecture of P. Pyykkö that QED effects are observable for the AuCN molecule by directly calculating ground-state rotational constants B0 of the three isotopomers studied by microwave spectroscopy; QED brings the corresponding substitution Au–C bond length rs from 0.23 to 0.04 pm agreement with experiment. (ii) In regard to spectroscopic constants of van der Waals dimers M2 (M = Hg, Rn, Cn, Og), QED induces bond length expansions on the order of 0.15(0.30) pm for row 6(7) dimers. (iii) We confirm that there is a significant change of valence s population of Pb in the reaction PbH4 → PbH2 + H2, which is thereby a good candidate for observing QED effects in chemical reactions, as proposed in [K. G. Dyall et al., Chem. Phys. Lett. 348, 497 (2001)]. We also find that whereas in PbH4 the valence 6s1/2 population resides in bonding orbitals, it is mainly found in nonbonding orbitals in PbH2. QED contributes 0.32 kcal/mol to the reaction energy, thereby reducing its magnitude by −1.27%. For corresponding hydrides of superheavy flerovium, the electronic structures are quite similar. Interestingly, the QED contribution to the reaction energy is of quite similar magnitude (0.35 kcal/mol), whereas the relative change is significantly smaller (−0.50%). This curious observation can be explained by the faster increase in negative vacuum polarization over positive electron self-energy contributions as a function of nuclear charge. [ABSTRACT FROM AUTHOR]

Ytterbium silicide-based thermoelectric materials have attracted attention because they exhibit large power factors owing to large absolute values of their Seebeck coefficient as well as high electrical conductivity. Here, we demonstrate that, in the Yb(Si1−xGex)2 system, by controlling the valence fluctuation, we combine two phenomena, namely, the Kondo effect and suppression of the spin fluctuation. This leads to a large density of states and the suppression of the spin fluctuation of the 4f electrons, thereby resulting in a high Seebeck coefficient with extremely low resistivity. Consequently, Yb(Si0.5Ge0.5)2 exhibits a high-power factor of 8.4 mW K−2 m−1, which makes energy harvesting from a cold source a practical possibility. [ABSTRACT FROM AUTHOR]

[Display omitted] Na 4 Fe 3 (PO 4) 2 (P 2 O 7) (NFPP) is currently drawing increased attention as a sodium-ion batteries (SIBs) cathode due to the cost-effective and NASICON-type structure features. Owing to the sluggish electron and Na+ conductivities, however, its real implementation is impeded by the grievous capacity decay and inferior rate capability. Herein, multivalent cation substituted microporous Na 3.9 Fe 2.9 Al 0.1 (PO 4) 2 (P 2 O 7) (NFAPP) with wide operation-temperature is elaborately designed through regulating structure/interface coupled electron/ion transport. Greatly, the derived Na vacancy and charge rearrangement induced by trivalent Al3+ substitution lower the ions diffusion barriers, thereby endowing faster electron transport and Na+ mobility. More importantly, the existing Al—O—P bonds strengthen the local environment and alleviate the volume vibration during (de)sodiation, enabling highly reversible valence variation and structural evolution. As a result, remarkable cyclability (over 10,000 loops), ultrafast rate capability (200 C), and exceptional all-climate stability (−40–60 °C) in half/full cells are demonstrated. Given this, the rational work might provide an actionable strategy to promote the electrochemical property of NFPP, thus unveiling the great application prospect of sodium iron mixed phosphate materials. [ABSTRACT FROM AUTHOR]

Binary metal oxide materials, such as nickel oxide, are widely used in flexible resistive variable memory devices due to advantages such as their easily controllable material composition, simple structural composition, and good compatibility between manufacturing processes and complementary metal oxide processes. In this work, a solution combustion method was employed to prepare NiOx thin films for use as a resistive switching layer of resistance random-access memory. The formation temperature of the NiOx layer in the RRAM device was kept as low as 175 °C, making the device compatible with flexible substrates. With polyethylene naphthalenediate as the substrate, the NiOx-based RRAM exhibited obvious bipolar resistance-switching properties, superb bending resistance, and good stability. Through theoretical fitting and structural characterization, the conduction mechanisms were attributed to the combination of the space-charge-limited current and Ohmic mechanisms, while the valence change mechanism was determined to be the resistive switching mechanism. This study demonstrates a low-temperature and scalable approach to constructing NiOx-based RRAM devices on flexible substrates. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Dalton Transactions: An International Journal of Inorganic Chemistry." It includes various articles and papers on topics such as copper complexes, lanthanide-based POMs, and coordination polymers. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document also mentions approved training courses offered by the society. The given document is a list of papers published in the journal Dalton Transactions. The papers cover a range of topics in chemistry, including catalysis, phosphors, materials synthesis, and more. Each paper is identified by its title, authors, and page number. The document also includes a correction and a retraction for two previously published papers. [Extracted from the article]

Cobalt dioxolenes are a well-known class of switchable coordination compounds showing intramolecular electron transfer, which is always accompanied by a spin state change at the cobalt center. Here, we present the first example of thermally switchable cobalt bis-dioxolenes where intramolecular electron transfer seems to take place, but the spin state change is suppressed. This leads to the detection of thermal transition between a common ls-CoIII(SQ˙−)(Cat2−) and an extremely rare ls-CoII(SQ˙−)2 electronic state (hs – high-spin, ls – low-spin, SQ˙− – benzosemiquinonate(1−) radical and Cat2− – catecholate(2−)). Parallel to the present work, a similar work but on cobalt mono-dioxolenes has just appeared (Chem. Eur. J., 2023, 29, e202300091), suggesting thermal transition between ls-CoIII(Cat2−) and ls-CoII(SQ˙−) electronic states. [ABSTRACT FROM AUTHOR]

Nucleophile oxidation reactions, represented by the incomplete methanol oxidation reaction (i-MOR) to formic acid, can effectively lower the potential of electrolytic hydrogen production while generating high-value products. In order to achieve an industrial grade i-MOR coupled with hydrogen production, designing efficient catalysts toward the i-MOR becomes crucial. In this work, a nickel–cobalt-layered double hydroxide (NiCo-LDH) catalyst incorporating an Fe-based "electron pump" is developed in accordance with the classic two-step NOR mechanism of Ni-based active sites. The coordinating effect of Co effectively reduces the oxidation potential of Ni(II / III) in NiCo-LDH, thus reducing the potential differential between it and the oxidation potential of Fe(II / III), consequently establishing an efficient electron transport pathway from Ni to Fe. Owing to the spontaneous dehydrogenation of methanol, elemental Fe can achieve a valence change during the i-MOR catalytic process. The "electron pump" composed of valence-change Fe effectively enhances the electron transfer, thus ensuring the efficient utilization of electron-deficient active Ni sites throughout the catalytic process. Therefore, FeEP-NiCo-LDH demonstrates outstanding i-MOR catalytic activity, with a potential requirement of 1.349 V (vs. RHE) and 1.430 V to deliver current densities of 10 mA cm−2 and 100 mA cm−2, respectively, while maintaining a Faraday efficiency of ca. 95%. [ABSTRACT FROM AUTHOR]