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1.
Proc Natl Acad Sci U S A ; 121(23): e2403726121, 2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38805293

ABSTRACT

The key of heterostructure is the combinations created by stacking various vdW materials, which can modify interlayer coupling and electronic properties, providing exciting opportunities for designer devices. However, this simple stacking does not create chemical bonds, making it difficult to fundamentally alter the electronic structure. Here, we demonstrate that interlayer interactions in heterostructures can be fundamentally controlled using hydrostatic pressure, providing a bonding method to modify electronic structures. By covering graphene with boron nitride and inducing an irreversible phase transition, the conditions for graphene lattice-matching bonding (IMB) were created. We demonstrate that the increased bandgap of graphene under pressure is well maintained in ambient due to the IMB in the interface. Comparison to theoretical modeling emphasizes the process of pressure-induced interfacial bonding, systematically generalizes, and predicts this model. Our results demonstrate that pressure can irreversibly control interlayer bonding, providing opportunities for high-pressure technology in ambient applications and IMB engineering in heterostructures.

2.
Nature ; 579(7797): 67-72, 2020 03.
Article in English | MEDLINE | ID: mdl-32094661

ABSTRACT

The Hall-Petch relationship, according to which the strength of a metal increases as the grain size decreases, has been reported to break down at a critical grain size of around 10 to 15 nanometres1,2. As the grain size decreases beyond this point, the dominant mechanism of deformation switches from a dislocation-mediated process to grain boundary sliding, leading to material softening. In one previous approach, stabilization of grain boundaries through relaxation and molybdenum segregation was used to prevent this softening effect in nickel-molybdenum alloys with grain sizes below 10 nanometres3. Here we track in situ the yield stress and deformation texturing of pure nickel samples of various average grain sizes using a diamond anvil cell coupled with radial X-ray diffraction. Our high-pressure experiments reveal continuous strengthening in samples with grain sizes from 200 nanometres down to 3 nanometres, with the strengthening enhanced (rather than reduced) at grain sizes smaller than 20 nanometres. We achieve a yield strength of approximately 4.2 gigapascals in our 3-nanometre-grain-size samples, ten times stronger than that of a commercial nickel material. A maximum flow stress of 10.2 gigapascals is obtained in nickel of grain size 3 nanometres for the pressure range studied here. We see similar patterns of compression strengthening in gold and palladium samples down to the smallest grain sizes. Simulations and transmission electron microscopy reveal that the high strength observed in nickel of grain size 3 nanometres is caused by the superposition of strengthening mechanisms: both partial and full dislocation hardening plus suppression of grain boundary plasticity. These insights contribute to the ongoing search for ultrastrong metals via materials engineering.

3.
Nano Lett ; 24(3): 966-974, 2024 Jan 24.
Article in English | MEDLINE | ID: mdl-38206580

ABSTRACT

Two-dimensional (2D) Fe chalcogenides with their rich structures and properties are highly desirable for revealing the torturous transition mechanism of Fe chalcogenides and exploring their potential applications in spintronics and nanoelectronics. Hydrostatic pressure can effectively stimulate phase transitions between various ordered states, allowing one to successfully plot a phase diagram for a given material. Herein, the structural evolution and transport characteristics of 2D FeTe were systematically investigated under extreme conditions by comparing two distinct symmetries, i.e., tetragonal (t) and hexagonal (h) FeTe. We found that t-FeTe presented a pressure-induced transition from an antiferromagnetic state to a ferromagnetic state at ∼3 GPa, corresponding to the tetragonal collapse of the layered structure. Contrarily, the ferromagnetic order of h-FeTe was retained up to 15 GPa, which was evidently confirmed by electrical transport and Raman measurements. Furthermore, T-P phase diagrams for t-FeTe and h-FeTe were mapped under delicate critical conditions. Our results can provide a unique platform to elaborate the extraordinary properties of Fe chalcogenides and further develop their applications.

4.
J Am Chem Soc ; 146(21): 14875-14888, 2024 May 29.
Article in English | MEDLINE | ID: mdl-38750611

ABSTRACT

Most of the nanozymes have been obtained based on trial and error, for which the application is usually compromised by enzymatic activity regulation due to a vague catalytic mechanism. Herein, a hollow axial Mo-Pt single-atom nanozyme (H-MoN5@PtN4/C) is constructed by a two-tier template capture strategy. The axial ligand can induce Mo 4d orbital splitting, leading to a rearrangement of spin electrons (↑ ↑ → ↑↓) to regulate enzymatic activity. This creates catalase-like activity and enhances oxidase-like activity to catalyze cascade enzymatic reactions (H2O2 → O2 → O2•-), which can overcome tumor hypoxia and accumulate cytotoxic superoxide radicals (O2•-). Significantly, H-MoN5@PtN4/C displays destructive d-π conjugation between the metal and substrate to attenuate the restriction of orbitals and electrons. This markedly improves enzymatic performance (catalase-like and oxidase-like activity) of a Mo single atom and peroxidase-like properties of a Pt single atom. Furthermore, the H-MoN5@PtN4/C can deplete overexpressed glutathione (GSH) through a redox reaction, which can avoid consumption of ROS (O2•- and •OH). As a result, H-MoN5@PtN4/C can overcome limitations of a complex tumor microenvironment (TME) for tumor-specific therapy based on TME-activated catalytic activity.


Subject(s)
Electrons , Ligands , Humans , Platinum/chemistry , Catalase/chemistry , Catalase/metabolism , Catalysis , Hydrogen Peroxide/chemistry , Hydrogen Peroxide/metabolism , Glutathione/chemistry , Glutathione/metabolism , Nanostructures/chemistry
5.
Small ; : e2400441, 2024 Apr 09.
Article in English | MEDLINE | ID: mdl-38593335

ABSTRACT

Electrochemical reduction of carbon dioxide (CO2RR) to formate is economically beneficial but suffers from poor selectivity and high overpotential. Herein, enriched microcrystalline copper oxide is introduced on the surface of indium-based metal-organic frameworks. Benefiting from the CuO (111) microcrystalline shell and formed catalytic active In-Cu interfaces, the obtained MIL-68(In)/CuO heterostructure display excellent CO2RR to formate with a Faradaic efficiency (FE) as high as 89.7% at low potential of only -0.7 V vs. RHE in a flow cell. Significantly, the membrane electrode assembly (MEA) cell based on MIL-68(In)/CuO exhibit a remarkable current density of 640.3 mA cm-2 at 3.1 V and can be stably operated for 180 h at 2.7 V with a current density of 200 mA cm-2. The ex/in situ electrochemical investigations reveal that the introduction of CuO increases the formation rate of the carbon dioxide reduction intermediate *HCOO- and inhibits the competitive hydrogen evolution reaction. This work not only provides an in-depth study of the mechanism of the CO2RR pathways on In/Cu composite catalyst but also offers an effective strategy for the interface design of electrocatalytic carbon dioxide reduction reaction.

6.
Small ; 20(16): e2309509, 2024 Apr.
Article in English | MEDLINE | ID: mdl-37992240

ABSTRACT

Noble metal single-atom-catalysts (SACs) have demonstrated significant potential to improve atom utilization efficiency and catalytic activity for hydrogen evolution reaction (HER). However, challenges still remain in rationally modulating active sites and catalytic activities of SACs, which often results in sluggish kinetics and poor stability, especially in neutral/alkaline media. Herein, precise construction of Pt single atoms anchored on edge of 2D layered Ni(OH)2 (Pt-Ni(OH)2-E) is achieved utilizing in situ electrodeposition. Compared to the single-atom Pt catalysts anchored on the basal plane of Ni(OH)2 (Pt-Ni(OH)2-BP), the Pt-Ni(OH)2-E possesses superior electron affinity and high intrinsic catalytic activity, which favors the strong adsorption and rapid dissociation toward water molecules. As a result, the Pt-Ni(OH)2-E catalyst requires low overpotentials of 21 and 34 mV at 10 mA cm-2 in alkaline and neutral conditions, respectively. Specifically, it shows the high mass activity of 23.6 A mg-1 for Pt at the overpotential of 100 mV, outperforming the reported catalysts and commercial Pt/C. This work provides new insights into the rational design of active sites for preparing high-performance SACs.

7.
Small ; : e2312019, 2024 Feb 22.
Article in English | MEDLINE | ID: mdl-38389179

ABSTRACT

The growing interest in so-called interface coupling strategies arises from their potential to enhance the performance of active electrode materials. Nevertheless, designing a robust coupled interface in nanocomposites for stable electrochemical processes remains a challenge. In this study, an epitaxial growth strategy is proposed by synthesizing sulfide rhenium (ReS2 ) on exfoliated black phosphorus (E-BP) nanosheets, creating an abundance of robust interfacial linkages. Through spectroscopic analysis using X-ray photoelectron spectroscopy and X-ray absorption spectroscopy, the authors investigate the interfacial environment. The well-developed coupled interface and structural stability contribute to the impressive performance of the 3D-printed E-BP@ReS2 -based micro-supercapacitor, achieving a specific capacitance of 47.3 mF cm-2 at 0.1 mA cm-2 and demonstrating excellent long-term cyclability (89.2% over 2000 cycles). Furthermore, density functional theory calculations unveil the positive impact of the strongly coupled interface in the E-BP@ReS2 nanocomposite on the adsorption of H+ ions, showcasing a significantly reduced adsorption energy of -2.17 eV. The strong coupling effect facilitates directional charge delocalization at the interface, enhancing the electrochemical performance of electrodes and resulting in the successful construction of advanced micro-supercapacitors.

8.
Small ; : e2402338, 2024 Jun 24.
Article in English | MEDLINE | ID: mdl-38924259

ABSTRACT

A frozen-temperature (below -28 °C) laser tuning way is developed to optimize metal halide perovskite (MHP)'s stability and opto-electronic properties, for emitter, photovoltaic and detector applications. Here freezing can adjust the competitive laser irradiation effects between damaging and annealing/repairing. And the ligand shells on MHP surface, which are widely present for many MHP materials, can be frozen and act as transparent solid templates for MHP's re-crystallization/re-growth during the laser tuning. With model samples of different types of CsPbBr3 nanocube arrays,an attempt is made to turn the dominant exposure facet from low-energy [100] facet to high-energy [111], [-211], [113] and [210] ones respectively; selectively removing the surface impurities and defects of CsPbBr3 nanocubes to enhance the irradiation durability by 101 times; and quickly (tens of seconds) modifying a Ruddlesden-Popper (RP) boundary into another type of boundary like twinning, and so on. The laser tuning mechanism is revealed by an innovative in situ cryo-transmission electron microscope (cryo-TEM) exploration at atomic resolution.

9.
J Chem Phys ; 160(3)2024 Jan 21.
Article in English | MEDLINE | ID: mdl-38235798

ABSTRACT

MnBi2Te4 can generate a variety of exotic topological quantum states, which are closely related to its special structure. We conduct comprehensive multiple-cycle high-pressure research on MnBi2Te4 by using a diamond anvil cell to study its phase transition behaviors under high pressure. As observed, when the pressure does not exceed 15 GPa, the material undergoes an irreversible metal-semiconductor-metal transition, whereas when the pressure exceeds 17 GPa, the layered structure is damaged and becomes irreversibly amorphous due to the lattice distortion caused by compression, but it is not completely amorphous, which presents some nano-sized grains after decompression. Our investigation vividly reveals the phase transition behaviors of MnBi2Te4 under high pressure cycling and paves the experimental way to find topological phases under high pressure.

10.
Postgrad Med J ; 100(1180): 112-119, 2024 Jan 21.
Article in English | MEDLINE | ID: mdl-37973392

ABSTRACT

PURPOSE: We aimed to investigate whether folate receptor α (FRα)-positive circulating tumour cells (CTCs) could be used as a noninvasive liquid biopsy approach in gastric cancer (GC). METHODS: Tissue microarray and bioinformatic analyses were used to evaluate FRα expression in GC. Patients with FRα-positive CTC examinations at our institute between July 2021 and May 2022 were retrospectively evaluated. Receiver operating characteristic curves were used to evaluate the diagnostic performance of FRα-positive CTCs in GC. RESULTS: FRα was highly expressed and associated with poor prognosis in GC based on public database. Data for 163 patients (20 with benign disease and 143 with GC) were retrospectively collected. FRα-positive CTC levels were significantly higher in the GC group than in the benign disease group (12.15 ± 1.47 FU/3 ml vs. 10.47 ± 1.63 FU/3 ml, P < 0.01). FRα-positive CTC levels were also elevated in GC patients with vessel/neuron invasion or extra-nodal tumour deposits (12.31 ± 1.47 FU/3 ml vs. 11.77 ± 1.38 FU/3 ml, P = 0.037). Areas under the curve of FRα-positive CTC levels for GC and early GC were 0.774 (P < 0.001) and 0.736 (P = 0.005). With a cut-off value of 10.95 FU/3 ml, the Youden indexes for GC and early GC were 0.502 (sensitivity = 85.2% and specificity = 65.0%) and 0.450 (sensitivity = 80.0% and specificity = 65.0%), respectively. CONCLUSION: FRα-positive CTC detection by noninvasive liquid biopsy is a useful and effective approach for screening of patients with GC.


Subject(s)
Neoplastic Cells, Circulating , Stomach Neoplasms , Humans , Folate Receptor 1/metabolism , Retrospective Studies , Stomach Neoplasms/diagnosis , Neoplastic Cells, Circulating/metabolism , Neoplastic Cells, Circulating/pathology , ROC Curve
11.
J Am Chem Soc ; 145(39): 21387-21396, 2023 Oct 04.
Article in English | MEDLINE | ID: mdl-37728869

ABSTRACT

The electrocatalytic nitrate (NO3-) reduction reaction (eNITRR) is a promising method for ammonia synthesis. However, its efficacy is currently limited due to poor selectivity, largely caused by the inherent complexity of the multiple-electron processes involved. To address these issues, oxygen-vacancy-rich LaFe0.9M0.1O3-δ (M = Co, Ni, and Cu) perovskite submicrofibers have been designed from the starting material LaFeO3-δ (LF) by a B-site substitution strategy and used as the eNITRR electrocatalyst. Consequently, the LaFe0.9Cu0.1O3-δ (LF0.9Cu0.1) submicrofibers with a stronger Fe-O hybridization, more oxygen vacancies, and more positive surface potential exhibit a higher ammonia yield rate of 349 ± 15 µg h-1 mg-1cat. and a Faradaic efficiency of 48 ± 2% than LF submicrofibers. The COMSOL Multiphysics simulations demonstrate that the more positive surface of LF0.9Cu0.1 submicrofibers can induce NO3- enrichment and suppress the competing hydrogen evolution reaction. By combining a variety of in situ characterizations and density functional theory calculations, the eNITRR mechanism is revealed, where the first proton-electron coupling step (*NO3 + H+ + e- → *HNO3) is the rate-determining step with a reduced energy barrier of 1.83 eV. This work highlights the positive effect of cation substitution in promoting eNITRR properties of perovskites and provides new insights into the studies of perovskite-type electrocatalytic ammonia synthesis catalysts.

12.
Small ; 19(5): e2205122, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36461717

ABSTRACT

The rapid capacity degradation and poor rate capability hinder the application of Rich-Ni layered LiNix Coy Mnz O2 (NCM) as cathode materials for high-energy lithium-ion batteries. In this study, density functional theory (DFT) calculations, combined with conventional electrochemical measurements, reveal from the atomic view that the dual improvements in electronic and ionic conductivities are the main facts for the property enhancement. The bandgap of the cathode material is reduced to 1.1623 eV due to the increased number of electrons near the Fermi level after W intercalation. Such improved electronic conductivity subsequently leads to a suppressed polarization and reduced resistance, enabling an improved cycle life of up to 93.97% after 100 cycles at 0.5 C. Furthermore, the doping with W6+ also introduced a strong WO bond into the layered structure so that the thickness of the Li slab is expanded to 2.6476 Å, which reduces the energy barrier from 0.355 to 0.308 eV for the migration of Li+ within the Li slab, as confirmed by the DFT calculation. Consequently, the rate performance is greatly improved due to the reduced diffusion energy, with a specific capacity of 159.11 mAg-1 even at 5 C rate, indicating high potential for future applications.

13.
Small ; 19(23): e2207505, 2023 Jun.
Article in English | MEDLINE | ID: mdl-36890774

ABSTRACT

Niobium-carbide (Nb2 C) MXene as a new 2D material has shown great potential for application in photovoltaics due to its excellent electrical conductivity, large surface area, and superior transmittance. In this work, a novel solution-processable poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-Nb2 C hybrid hole transport layer (HTL) is developed to enhance the device performance of organic solar cells (OSCs). By optimizing the doping ratio of Nb2 C MXene in PEDOT:PSS, the best power convention efficiency (PCE) of 19.33% can be achieved for OSCs based on the ternary active layer of PM6:BTP-eC9:L8-BO, which is so far the highest value among those of single junction OSCs using 2D materials. It is found that the addition of Nb2 C MXene can facilitate the phase separation of the PEDOT and PSS segments, thus improving the conductivity and work function of PEDOT:PSS. The significantly enhanced device performance can be attributed to the higher hole mobility and charge extraction capability, as well as lower interface recombination probabilities generated by the hybrid HTL. Additionally, the versatility of the hybrid HTL to improve the performance of OSCs based on different nonfullerene acceptors is demonstrated. These results indicate the promising potential of Nb2 C MXene in the development of high-performance OSCs.

14.
Nanotechnology ; 35(5)2023 Nov 15.
Article in English | MEDLINE | ID: mdl-37871598

ABSTRACT

The generation of disorder often gives rise to profound and irreversible physical phenomena. Here, we explore the influence of disorder on the superconducting properties of In2Te3through comprehensive high-pressure investigations. Building upon previous findings, we investigated the progressive suppression of superconductivity in In2Te3during the depressurization process: the increased disorder that ultimately leads to the complete disappearance of the superconducting state. Simultaneously, our high-pressure x-ray diffraction analysis reveals an irreversible structural phase transition. Furthermore, microstructure analysis using transmission electron microscopy clearly demonstrates both grain refinement and a substantial enhancement of disorder. These findings not only provide valuable insights into the mechanism by which disorder suppresses superconductivity, but also offer guidance for future advancements in the fabrication of atmospheric-pressure superconductors.

15.
Acta Pharmacol Sin ; 44(5): 1029-1037, 2023 May.
Article in English | MEDLINE | ID: mdl-36333557

ABSTRACT

Pulmonary fibrosis (PF) is a chronic interstitial lung disease with no effective therapies. Galectin-3 (Gal-3), a marker of oxidative stress, plays a key role in the pathogenesis of PF. Fibroblast-myofibroblast differentiation (FMD) is an important source of fibrotic cells in PF. Previous studies showed that melatonin (MT) exerted anti-fibrotic effect in many diseases including PF through its antioxidant activity. In the present study we investigated the relationships among Gal-3, NRF2, ROS in FMD and their regulation by MT. We established an in vitro model of FMD in TGF-ß1-treated human fetal lung fibroblast1 (HFL1) cells and a PF mouse model via bleomycin (BLM) intratracheal instillation. We found that Gal-3 expression was significantly increased both in vitro and in vivo. Knockdown of Gal-3 in HFL1 cells markedly attenuated TGF-ß1-induced FMD process and ROS accumulation. In TGF-ß1-treated HFL1 cells, pretreatment with NRF2-specific inhibitor ML385 (5 µM) significantly increased the levels of Gal-3, α-SMA and ROS, suggesting that the expression of Gal-3 was regulated by NRF2. Treatment with NRF2-activator MT (250 µM) blocked α-SMA and ROS accumulation accompanied by reduced Gal-3 expression. In BLM-induced PF model, administration of MT (5 mg·kg-1·d-1, ip for 14 or 28 days) significantly attenuated the progression of lung fibrosis through up-regulating NRF2 and down-regulating Gal-3 expression in lung tissues. These results suggest that Gal-3 regulates TGF-ß1-induced pro-fibrogenic responses and ROS production in FMD, and MT activates NRF2 to block FMD process by down-regulating Gal-3 expression. This study provides a useful clue for a clinical strategy to prevent PF. Graphic abstract of the mechanisms. MT attenuated BLM-induced PF via activating NRF2 and inhibiting Gal-3 expression.


Subject(s)
Melatonin , Pulmonary Fibrosis , Animals , Humans , Mice , Bleomycin/adverse effects , Fibroblasts , Galectin 3/drug effects , Galectin 3/metabolism , Lung/pathology , Melatonin/pharmacology , Melatonin/therapeutic use , NF-E2-Related Factor 2/drug effects , NF-E2-Related Factor 2/metabolism , Pulmonary Fibrosis/chemically induced , Pulmonary Fibrosis/drug therapy , Pulmonary Fibrosis/metabolism , Reactive Oxygen Species/metabolism , Transforming Growth Factor beta1/metabolism
16.
Nano Lett ; 22(8): 3503-3511, 2022 04 27.
Article in English | MEDLINE | ID: mdl-35315671

ABSTRACT

Metal ion substitution and anion exchange are two effective strategies for regulating the electronic and geometric structure of spinel. However, the optimal location of foreign metallic cations and the exact role of these metals and anions remain elusive. Herein, CoFe2O4-based hollow nanospheres with outstanding oxygen evolution reaction activity are prepared by Cr3+ substitution and S2- exchange. X-ray absorption spectra and theoretical calculations reveal that Cr3+ can be precisely doped into octahedral (Oh) Fe sites and simultaneously induce Co vacancy, which can activate adjacent tetrahedral (Td) Fe3+. Furthermore, S2- exchange results in structure distortion of Td-Fe due to compressive strain effect. The change in the local geometry of Td-Fe causes the *OOH intermediate to deviate from the y-axis plane, thus enhancing the adsorption of the *OOH. The Co vacancy and S2- exchange can adjust the geometric and electronic structure of Td-Fe, thus activating the inert Td-Fe and improving the electrochemical performance.


Subject(s)
Metals , Oxygen , Catalysis , Cations/chemistry , Metals/chemistry , Oxygen/chemistry
17.
Angew Chem Int Ed Engl ; 62(6): e202217220, 2023 Feb 01.
Article in English | MEDLINE | ID: mdl-36478508

ABSTRACT

Fine-tuning electronic structures of single-atom catalysts (SACs) plays a crucial role in harnessing their catalytic activities, yet challenges remain at a molecular scale in a controlled fashion. By tailoring the structure of graphdiyne (GDY) with electron-withdrawing/-donating groups, we show herein the electronic perturbation of Cu single-atom CO2 reduction catalysts in a molecular way. The elaborately introduced functional groups (-F, -H and -OMe) can regulate the valance state of Cuδ+ , which is found to be directly scaled with the selectivity of the electrochemical CO2 -to-CH4 conversion. An optimum CH4 Faradaic efficiency of 72.3 % was achieved over the Cu SAC on the F-substituted GDY. In situ spectroscopic studies and theoretical calculations revealed that the positive Cuδ+ centers adjusted by the electron-withdrawing group decrease the pKa of adsorbed H2 O, promoting the hydrogenation of intermediates toward the CH4 production. Our strategy paves the way for precise electronic perturbation of SACs toward efficient electrocatalysis.

18.
Angew Chem Int Ed Engl ; 62(9): e202214570, 2023 Feb 20.
Article in English | MEDLINE | ID: mdl-36581568

ABSTRACT

Purposely changing the rate-determining step (RDS) of oxygen evolution reaction (OER) remains a major challenge for enhancing the energy efficiency of electrochemical splitting of water. Here we show that the OER RDS can be regulated by simply varying the cation and anion complexity in a family of the metal phosphorous trichalcogenide electrocatalysts (MPT3 , where M=Fe, Ni; T=S, Se), achieving an exceptionally high OER activity in (Ni,Fe)P(S,Se)3 , as demonstrated by its ultra-low Tafel slope (34 mV dec-1 ) and a very low overpotential compared to many relevant OER catalysts. This is strongly supported by density functional theory calculations, which showed that this catalyst has a nearly optimal OER activity descriptor value of ΔG(O*)-ΔG(OH*)=1.5 eV. We also found that the activity descriptor is proportional to a newly proposed cation/anion complexity index that consists of pairwise contributions from cation-anion bonds in a catalyst compound, revealing the pivotal role of the cation-anion interactions in determining the catalyst performance and providing a simple way for predicting catalytic activities.

19.
Angew Chem Int Ed Engl ; 62(50): e202312409, 2023 Dec 11.
Article in English | MEDLINE | ID: mdl-37681482

ABSTRACT

Currently, single-atom catalysts (SACs) research mainly focuses on transition metal atoms as active centers. Due to their delocalized s/p-bands, the s-block main group metal elements are typically regarded as catalytically inert. Herein, an s-block potassium SAC (K-N-C) with K-N4 configuration is reported for the first time, which exhibits excellent oxygen reduction reaction (ORR) activity and stability under alkaline conditions. Specifically, the half-wave potential (E1/2 ) is up to 0.908 V, and negligible changes in E1/2 are observed after 10,000 cycles. In addition, the K-N-C offers an exceptional power density of 158.1 mW cm-2 and remarkable durability up to 420 h in a Zn-air battery. Density functional theory (DFT) simulations show that K-N-C has bifunctional active K and C sites, can optimize the free energy of ORR reaction intermediates, and adjust the rate-determining steps. The crystal orbital Hamilton population (COHP) results showed that the s orbitals of K played a major role in the adsorption of intermediates, which was different from the d orbitals in transition metals. This work significantly guides the rational design and catalytic mechanism research of s-block SACs with high ORR activity.

20.
Angew Chem Int Ed Engl ; 62(14): e202218282, 2023 Mar 27.
Article in English | MEDLINE | ID: mdl-36728690

ABSTRACT

Metallic conductive 1T phase molybdenum sulfide (MoS2 ) has been identified as promising anode for sodium ion (Na+ ) batteries, but its metastable feature makes it difficult to obtain and its restacking during the charge/discharge processing result in part capacity reversibility. Herein, a synergetic effect of atomic-interface engineering is employed for constructing 2H-MoS2 layers assembled on single atomically dispersed Fe-N-C (SA Fe-N-C) anode material that boosts its reversible capacity. The work-function-driven-electron transfer occurs from SA Fe-N-C to 2H-MoS2 via the Fe-S bonds, which enhances the adsorption of Na+ by 2H-MoS2 , and lays the foundation for the sodiation process. A phase transfer from 2H to 1T/2H MoS2 with the ferromagnetic spin-polarization of SA Fe-N-C occurs during the sodiation/desodiation process, which significantly enhances the Na+ storage kinetics, and thus the 1T/2H MoS2 /SA Fe-N-C display a high electronic conductivity and a fast Na+ diffusion rate.

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