Valence Variation Research Articles

UV­B Persistent Luminescence of CaF2:Gd3+ for Radiation Labeling and Tracing

AbstractPersistent luminescence (PersL) has attracted considerable attention in the last two decades for its potential applications in the fields of emergency indicators, energy‐saving lighting, biomedical imaging, and dynamic anti‐counterfeiting. However, the wavelengths of PersL reported so far usually fall into the visible and near‐infrared range. The preparation of advanced optical materials bearing UV PersL remains elusive. Here the PersL characteristic of CaF2:Gd3+ is systematically studied. After exposure to X‐ray radiation, CaF2:Gd3+ continues to emit UV­‐B (UVB) PersL peaking at 313 nm, corresponding to the 6P7/2 → 8S7/2 transition of Gd3+. By virtue of X‐ray photoelectron spectroscopy measurements, the valence variation model is excluded to explain the UVB PersL of CaF2:Gd3+. Finally, it is demonstrated that such UVB PersL of CaF2:Gd3+ can be used for static labeling and dynamic tracing.

Improved microwave dielectric properties of LaZn1/2Ti1/2O3 through Y3+ substitution

LaZn1/2Ti1/2O3 is a double perovskite with promising microwave dielectric properties for applications towards dielectric resonators and antennas. Its dielectric properties can be enhanced through the substitution of suitable ions in either A- or B-sites. In this paper, we report a significant improvement in the quality factor (Q) by substituting Y3+ in the La site with a marginal reduction in dielectric constant (εr). A single phase is confirmed in XRD indicating the formation of La1-xYxZn1/2Ti1/2O3 (0 ≤ x ≤ 0.25) solid solutions. The substitution results in an expansion of lattice along the b direction while there is a contraction in both a and c directions, leading to a reduction in unit cell volume. The dielectric constant, εr, is observed to reduce from 33.4 to 29.6 due to the polarizability of A-site atoms. The temperature coefficient of resonant frequency (τf) increases with an increase in x which does not appear to correlate with reducing tolerance factor (t). This non-conventional behaviour of τf in this perovskite based solid solutions brings bond valence of O site (VO) into picture. VO appears to show competing effect on τf. The non-monotonic behaviour is observed in Q×f with a maximum value of 41,400 GHz at x = 0.15 and a sharp decline for x > 0.15. This observation is correlated with variations in the A-site bond valence (VA) and a long-range ordering (LRO) of B-site ions. LRO is associated with Ag mode at 710 cm−1 in the Raman spectra. The low frequency (< 250 cm−1) Raman modes shift to a higher frequency with the increase in Y3+. Y3+ substitution also induces lattice distortion which is discussed in terms of variations in FWHM and relative intensity of the Raman modes.

Rare earth tantalate coating materials for thermal and oxidation protection of carbon-carbon composites

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 (YbTaO4 and LuTaO4) 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 LuTaO4 having a value of 1.903 W m−1 K−1 at 900 °C. Furthermore, LuTaO4 has decreased oxygen-ion conductivity due to a high activation energy and immobile vacancies. A LuTaO4/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.

Motivational context and neurocomputation of stop expectation moderate early attention responses supporting proactive inhibitory control.

Alterations in attention to cues signaling the need for inhibitory control play a significant role in a wide range of psychopathology. However, the degree to which motivational and attentional factors shape the neurocomputations of proactive inhibitory control remains poorly understood. The present study investigated how variation in monetary incentive valence and stake modulate the neurocomputational signatures of proactive inhibitory control. Adults (N = 46) completed a Stop-Signal Task (SST) with concurrent EEG recording under four conditions associated with stop performance feedback: low and high punishment (following unsuccessful stops) and low and high reward (following successful stops). A Bayesian learning model was used to infer individual's probabilistic expectations of the need to stop on each trial: P(stop). Linear mixed effects models were used to examine whether interactions between motivational valence, stake, and P(stop) parameters predicted P1 and N1 attention-related event-related potentials (ERPs) time-locked to the go-onset stimulus. We found that P1 amplitudes increased at higher levels of P(stop) in punished but not rewarded conditions, although P1 amplitude differences between punished and rewarded blocks were maximal on trials when the need to inhibit was least expected. N1 amplitudes were positively related to P(stop) in the high punishment condition (low N1 amplitude), but negatively related to P(stop) in the high reward condition (high N1 amplitude). Critically, high P(stop)-related N1 amplitude to the go-stimulus predicted behavioral stop success during the high reward block, providing evidence for the role of motivationally relevant context and inhibitory control expectations in modulating the proactive allocation of attentional resources that affect inhibitory control. These findings provide novel insights into the neurocomputational mechanisms underlying proactive inhibitory control under valence-dependent motivational contexts, setting the stage for developing motivation-based interventions that boost inhibitory control.

Dissecting Whiteness: consistencies and differences in the stereotypes of lower- and upper-class White US Americans

ABSTRACT Economic inequality is increasing in the United States, making categorization and stereotyping based on social class more likely. Yet, social class stereotypes have received relatively little attention. Focusing on spontaneously generated stereotypes of different White lower-class and upper-class groups in the United States, we find consistencies and differences across groups. Lower-class groups were stereotyped as poor, uneducated, dirty, and lacking ability, while upper-class groups were stereotyped as rich, arrogant, and lacking sociability. Stereotypes for all groups were largely negative but there were notable variations in stereotype valence, sociability, morality, ability, and assertiveness as well as perceived attitudes toward the groups within each social class, highlighting the importance of moving beyond a monolithic view of “the rich” and “the poor.”

Aluminum ion chemistry of Na4Fe3(PO4)2(P2O7) for all-climate full Na-ion battery

Na4Fe3(PO4)2(P2O7) (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 Na3.9Fe2.9Al0.1(PO4)2(P2O7) (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.

The impact of emotional valence on generalization gradients

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.

Direct observation of strong surface reconstruction in partially reduced nickelate films

The polarity of a surface can affect the electronic and structural properties of oxide thin films through electrostatic effects. Understanding the mechanism behind these effects requires knowledge of the atomic structure and electrostatic characteristics at the surface. In this study, we use annular bright-field imaging to investigate the surface structure of a Pr0.8Sr0.2NiO2+x (0 < x < 1) film. We observe a polar distortion coupled with octahedral rotations in a fully oxidized Pr0.8Sr0.2NiO3 sample, and a stronger polar distortion in a partially reduced sample. Its spatial depth extent is about three unit cells from the surface. Additionally, we use four-dimensional scanning transmission electron microscopy (4D-STEM) to directly image the local atomic electric field surrounding Ni atoms near the surface and discover distinct valence variations of Ni atoms, which are confirmed by atomic-resolution electron energy-loss spectroscopy (EELS). Our results suggest that the strong surface reconstruction in the reduced sample is closely related to the formation of oxygen vacancies from topochemical reduction. These findings provide insights into the understanding and evolution of surface polarity at the atomic level.

Schematicity vs. lexicality: typological differences between Danish and Spanish

ABSTRACT The aim of this article is to demonstrate how Danish and Spanish from a typological, cross-linguistic perspective differ systematically from each other both within the domain of verbal lexicalization patterns related to the encoding of the semantic components Motion, Manner and Path and in terms of the predicate formation strategies dominating the two languages. First, on the basis of a contrastive analysis between the Spanish Motion-Path conflating verb pairs meter ‘insert’/sacar ‘extract’ and entrar ‘enter’/salir ‘exit’ and the Danish activity/Manner-of-motion verbs sprøjte ‘spray’ and stikke ‘stick’, it is argued that each language disposes of sets of abstract lexemes that do not exist in the other language. They lexicalize on different levels, one could say. Second, and strongly related to the first point, the article suggests that the preference of Danish to create complex schematic expression structures, where Spanish tends to concentrate information in monomorphemic, semantically saturated lexemes, can be explained by applying a template for valence variation that distinguishes between two basic and two extended sentence structures. Specifically, it is the (im)possibility of realizing the so-called A relation, the ‘third’ argument, that constitutes the differentiating factor between Danish and Spanish.

Study on the properties of sodium bismuth titanate coating prepared by supersonic plasma spraying

In order to realize the preparation of environmentally friendly piezoelectric ceramic coatings on the surface of metallic materials, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) ceramic coatings were prepared by supersonic plasma spraying. The surface morphology, cross-sectional morphology, phase structure, and elemental valence variations of the BNT coating were examined, as well as the dielectric and ferroelectric properties of the BNT coating. The results show that the coating has a good quality and a single perovskite structure. The dielectric constant was stable at about 425 and the dielectric loss was stable at about 0.06 when the test frequency reached 200 kHz. The coating exhibits good hysteresis lines under different applied electric fields. When the applied electric field was 40 kV/cm, the remnant polarization value of the prepared coating was 11.47 µC/cm2. It can be seen that the BNT piezoelectric coating prepared by supersonic plasma spraying has good ferroelectric and dielectric properties, which lays a solid foundation for in-situ monitoring of environmentally friendly lead-free BNT piezoelectric coating.

Unravelling the interplay of local structure and valence transitions in Ce-doped CaYAlO4 luminescent materials.

Cerium has been widely used as a dopant in luminescent materials due to its unique electronic configurations. It is generally anticipated that the luminescence properties of rare-earth-doped materials are closely related to the local environment of activators, especially for Ce3+ . In addition, it is convenient to modulate its emission wavelength by adjusting the composition and structure. In this study, we systematically analyzed the microstructure of the Ce-doped CaYAlO4 system at atomic resolution. The quantitive results indicated that the structure distortion greatly influenced the valence state of the Ce dopant, which is critical to its luminescence efficiency. In addition, valence variations also exist from surface to inner structure due to the big distortion area around the surface. Our results unravel the interplay of local structure and valence transitions in Ce-doped aluminate phosphors, which has the potential to be applied in other luminescent materials.

Functional near-infrared spectroscopy approach to the emotional regulation effect of drawing: Venting versus distraction.

Drawing can regulate emotions through venting or distraction. Distraction is more helpful for short-term emotion recovery; however, the sustainability of this difference is yet to be clarified. This study used functional near-infrared spectroscopy (fNIRS) to explore potential differences between venting and distraction. A total of 44 college students participated in the experiment. After inducing fear by video, they were divided into two groups: The venting group drew their emotional experience, and the distraction group drew a house. Subsequently, the participants were instructed to relax by a brief video. Although the distraction group had a higher valence than the venting group at the end of the drawing activity, there was no difference between the two groups after a relaxation period. Additionally, the activation pattern of the prefrontal cortex differed between the two groups. Compared to the distraction group, the venting group had fewer channels with elevated prefrontal activity during drawing, suggesting less cognitive control, and had more channels with reduced prefrontal activity during relaxation, suggesting a higher level of relaxation. Drawing coding and fNIRS data were both associated with variations in valence. The less the cognitive control over emotion and the more free the expression of emotion during drawing, the higher the increase in valence; inversely, the more the cognitive control over emotion and the less free the expression of emotion, the lower the increase in valence.

Low-temperature CO selective catalytic reduction denitrification and sulfuric acid regeneration mechanism of Cu-Ce/AC catalyst poisoned with zinc salt

To explore Cu–Ce/activated carbon (AC) catalyst poisoned of with zinc salt and its mechanism of low-temperature CO selective catalytic reduction (CO-SCR) denitrification following sulfuric acid regeneration, this paper uses ZnCl2 and ZnSO4 to poison Cu–Ce/AC catalyst and H2SO4 pickling to regenerate the poisoned catalyst. Not only the catalyst denitrification activity was investigated but also the surface morphology, pore structure, variation of active component phases and elemental valence, surface functional groups, reduction characteristics and adsorption mechanism of catalyst before and after regeneration were systematically characterized. The low-temperature CO-SCR denitrification mechanism of the poisoned Cu–Ce/AC catalyst was revealed. After being poisoned with zinc salt, the oxide on the catalyst surface aggregated, causing the blockage of the pore, thereby inhibiting the adsorption capacity of the reaction gas and the synergistic reaction between Cu-Ce. Moreover, zinc salt not only occupies the active site, but also destroys the -C=O and –OH oxygen-containing functional groups. This not only reduces the chemically adsorbed oxygen (Oβ) and oxygen vacancy but also leads to the reduction of Cu+–CO species, the reduction of catalyst redox capacity, and the reduction of NO conversion rate. The regeneration mechanism of the sulfuric acid method was as follows. First, the solid particles deposited on the catalyst surface are removed, thereby restoring its specific surface area and pore structure, and increasing the adsorption area of reaction gas. Additionally, the content of Cu and Ce active components was increased, which promoted the synergistic reaction, and the content of Cu+–CO species, oxygen vacancy, and Oβ was increased, resulting in enhanced redox capacity. Finally, sulfuric acid impregnation generated S2O82− groups, which sulfated the surface of the catalyst, and its S=O reacted with Zn to form S–O–S, which prevented zinc salt from destroying the oxygen-containing functional groups and improved the reducing capacity and CO adsorption capacity of the catalyst, thereby restoring the denitrification activity of the catalyst.

Correlation between Si-Al disorder and hydrogen-bonding distance variation in ussingite (Na2AlSi3O8OH) revealed by one- and two-dimensional multi-nuclear NMR and first-principles calculation

Abstract 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.

Study on controllable preparation of high performance andradite based glass-ceramics by harmful iron-rich waste slag

Due to containing abundant FeOx and trace heavy metals (Pb, As, Cr, Cd, etc.), the disposal of lead/zinc smelting slag (LSS-ZSS) with ultra-high historical reserves has attracted increased attention. Using LSS-ZSS to prepare glass-ceramics is a good method to solve the problem of LSS-ZSS accumulation and realize heavy metal solidification, whereas there are some technical challenges that are difficult to deal with. A large amount of FeOx component in LSS-ZSS would not only lead to melt overflow, but also cause early crystallization of basic glass. In this work, through the directional modification of LSS-ZSS and the subsequent crystallization kinetics regulation, we successfully prepare high performance glass-ceramics with andradite and hematite as the main crystal phases. In addition, by means of SEM, PXRD, FTIR spectra and XPS, the morphology/phase transformation, fine structure and valence variations of iron components in LSS-ZSS at different temperature zones are systematically studied. The maximum shrinkage rate of resultant basic glasses is 27 %, and the maximum flexural strength and compressive strength of glass-ceramics are 128 MPa and 890 MPa, respectively. This work would not only benefit to solve the problem of resource utilization of harmful LSS-ZSS, but also provide a possible reference for the utilization of iron-rich waste slag in magnetic properties related fields.

In-situ growth of porous rod-like tungsten oxide for electrochemical determination of cupric ion

Preconcentration can effectively enhance the detection performance of electrodes in the electrochemical detection of heavy metal ions, but it also presents challenges for real-time monitoring. Several attempts have been made to optimize preconcentration by improving the adsorption capacity or detection mechanism of the electrode. The valence transfer of tungsten oxide between W5+/W6+ can participate in the reduction between the electrode material and heavy metal ions, playing a role in preconcentration to some extent. Therefore, we developed a WO3/SSM electrochemical sensor for the detection of Cu(II) that utilizes the valence variation property of WO3. The crystallinity and microstructure of the WO3/SSM electrode can be regulated by controlling the deposition parameters, and we prepared three types of WO3/SSM with different morphologies to identify the influence of the electrochemical effective surface area. The proposed electrode shows high performance as a Cu(II) sensor under short preconcentration time (60 s), with an excellent sensitivity of 14.113 μA μM−1 cm−2 for 0.1–10.0 μM and 4.7356 μA μM−1 cm−2 for 10.0–20.0 μM. Overall, the combined effect of morphology and valence transfers shortens the preconcentration time and optimizes preconcentration while ensuring excellent electrode performance. This WO3/SSM electrode is expected to drive great advances in the application of tungsten oxide in the electrochemical detection of heavy metal ions.

Solubility and Valence Variation of Ce in Low-Alkali Borosilicate Glass and Glass Network Structure Analysis.

Low-alkali borosilicate glass was used as the immobilization substrate, and Ce was used to replicate the trivalent and tetravalent actinides, in order to create simulated waste glass through melt heat treatment. The valence of Ce and solubility of CeO2 in waste glass were studied as well as its network structure and thermal and chemical stability. The solubility of Ce in waste glass was examined by XRD and SEM. The network structure was examined by Raman spectroscopy. The valence of Ce was determined by X-ray photoelectron spectroscopy. Thermal analysis and product consistency (PCT) were employed to determine the thermal and chemical stability of waste glasses. The results show that the solubility of cerium in low-alkali borosilicate glasses is at least 25.wt.% and precipitates a spherical CeO2 crystalline phase when it exceeds the solid solution limit; Ce is immobilized in the glass by entering the interstices of the glass network. Depolymerization and the transition from [BO3] to [BO4] occurs when CeO2 doping levels rise. About 60 percent of Ce4+ is converted to Ce3+, and the thermal stability of glass rises then falls with the increase of CeO2. All samples exhibit strong leaching resistance, with the average mass loss of Ce at 28 days being less than 10-4 gm-2d-1.

Metal-insulator transition tuned by valence variation of Nb dopants in Nb-doped VO2 films

High-valence cation doping was proved to be an effective method in reducing the high metal–insulator transition (MIT) temperature (θc). However, the mechanism of cation-dopants reducing θc is not quite clear and the reported data about the θc reduction induced by Nb dopants are dispersive. In this work, we prepared Nb-doped VO2 films by hydrothermal process and investigated the effects of Nb dopants on the MIT behavior. Valence variation of Nb dopants was observed in the Nb-doped VO2. The Nb5+ dopants elevate the valence band top to higher level than the Nb4+-containing sample. Correspondingly, the Nb5+ doping reduces θc in a higher rate of ∼21 ℃/at%Nb than the Nb4+-containing sample which has the decline rate of ∼18 ℃/at%Nb. The results imply Nb5+ dopants contributing excess electrons modify the band structure and consequently promoting the MIT transition. In addition, the Nb doping realizes the θc reduction almost without detriment to the optical properties of VO2, suggesting the promising applications in smart window and other optical switching devices.

A Curcumin-Modified Coordination Polymers with ROS Scavenging and Macrophage Phenotype Regulating Properties for Efficient Ulcerative Colitis Treatment.

Overexpression of classically activated macrophages (M1) subtypes and assessed reactive oxygen species (ROS) levels are often observed in patients with ulcerative colitis. At present, the treatment system of these two problems has yet to be established. Here, the chemotherapy drug curcumin (CCM) is decorated with Prussian blue analogs in a straightforward and cost-saving manner. Modified CCM can be released in inflammatory tissue (acidic environment), eventually causing M1 macrophages to transform into M2 macrophages and inhibiting pro-inflammatory factors. Co(III) and Fe(II) have abundant valence variations, and the lower REDOX potential in CCM-CoFe PBA enables ROS clearance through multi-nanomase activity. In addition, CCM-CoFe PBA effectively alleviated the symptoms of UC mice induced by DSS and inhibited the progression of the disease. Therefore, the present material may be used as a new therapeutic agent for UC.

Design of 2D/2D heterostructure by coupling cobalt hydroxides with Mxene on nickel foam for high energy density supercapacitors

Two-dimensional (2D) layered transition metal compounds are promising pseudocapacitive materials for high-performance supercapacitors. Herein, the cobalt hydroxide coupled Ti3C2Tx MXene layers on nickel foam (Co(OH)2-Ti3C2Tx@NF) is prepared by the facile hydrothermal method. The 2D/2D heterostructures by coupling layered double hydroxide (LDH) with MXene can expose the more specific surface area and boost the redox-active sites. Co(OH)2-Ti3C2Tx@NF exhibits a higher specific capacitance (1400 F g−1) than Co(OH)2@NF (1106 F g−1) and Ti3C2Tx@NF (844 F g−1), and the capacitance retention is 98.2 % after 10,000 cycles implying outstanding cyclic stability. Excellent pseudocapacitive behavior is assigned to the redox reaction by the interaction of MXene with alkali metal ions and the valence variations of Co3+/Co2+. Furthermore, the assembled asymmetric Co(OH)2-Ti3C2Tx@NF//AC supercapacitor shows an energy density of 13.7 μWh cm−2 at 1.4 mW cm−2. These results imply that the LDH/MXene hybrid with 2D/2D heterostructures can be considered promising pseudocapacitive electrode materials for high-energy supercapacitors.