Structural design of advanced cathodes is a promising strategy to suppress the shuttle effect for lithium‐sulfur batteries (LSBs). In this work, the carbon cloth covered with CoS2 nanoparticles ...(CC‐CoS2) is prepared to function as both three‐dimensional (3D) current collector and physicochemical barrier to retard migration of soluble lithium polysulfides. On the one hand, the CC‐CoS2 film works as a robust 3D current collector and host with high conductivity, high sulfur loading, and high capability of capturing polysulfides. On the other hand, the 3D porous CC‐CoS2 film serves as a multifunctional interlayer that exhibits efficient physical blocking, strong chemisorption, and fast catalytic redox reaction kinetics toward soluble polysulfides. Consequently, the Al@S/AB@CC‐CoS2 cell with a sulfur loading of 1.2 mg cm−2 exhibits a high rate capability (≈823 mAh g−1 at 4 C) and delivers excellent capacity retention (a decay of ≈0.021% per cycle for 1000 cycles at 4 C). Moreover, the sandwiched cathode of CC‐CoS2@S/AB@CC‐CoS2 is designed for high sulfur loading LSBs. The CC‐CoS2@S/AB@CC‐CoS2 cells with sulfur loadings of 4.2 and 6.1 mg cm−2 deliver high reversible capacities of 1106 and 885 mAh g−1, respectively, after 100 cycles at 0.2 C. The outstanding electrochemical performance is attributed to the sandwiched structure with active catalytic component.
Sandwiched cathodes constructed from CoS2‐modified carbon clothes (CC‐CoS2) are designed for high sulfur loading lithium‐sulfur batteries. The sandwiched cathode not only offers three‐dimensional (3D) current collector and host with enough voids for volume expansion to maintain the structural stability, but also promotes the physical encapsulation, chemical entrapment and catalytic conversion of polysulfides species to suppress the shuttle effect.
Abstract
Layered double hydroxides are promising candidates for the electrocatalytic oxygen evolution reaction. Unfortunately, their catalytic kinetics and long-term stabilities are far from ...satisfactory compared to those of rare metals. Here, we investigate the durability of nickel-iron layered double hydroxides and show that ablation of the lamellar structure due to metal dissolution is the cause of the decreased stability. Inspired by the amino acid residues in photosystem II, we report a strategy using trimesic acid anchors to prepare the subsize nickel-iron layered double hydroxides with kinetics, activity and stability superior to those of commercial catalysts. Fundamental investigations through operando spectroscopy and theoretical calculations reveal that the superaerophobic surface facilitates prompt release of the generated O
2
bubbles, and protects the structure of the catalyst. Coupling between the metals and coordinated carboxylates via C‒O‒Fe bonding prevents dissolution of the metal species, which stabilizes the electronic structure by static coordination. In addition, the uncoordinated carboxylates formed by dynamic evolution during oxygen evolution reaction serve as proton ferries to accelerate the oxygen evolution reaction kinetics. This work offers a promising way to achieve breakthroughs in oxygen evolution reaction stability and dynamic performance by introducing functional ligands with static and dynamic compatibilities.
Electrocatalytic carbon dioxide reduction reaction (CO
2
RR) is a promising method to deal with the greenhouse effect and the energy crisis. In a well-designed Cu-based catalyst, the unique crystal ...structure with active electronic properties is crucial for CO
2
RR. Here, a series of copper hydroxyphosphate catalysts were synthesized via one-step solvothermal process and applied in CO
2
RR. The concentration of hydroxide ion (OH
−
) and ammonium ion (NH
4
+
) plays an important role in the formation and aggregation of the crystal architectures. Compared to copper monohydroxyphosphate (Cu
2
(OH)PO
4
), copper tetrahydroxyphosphate (Cu
5
(OH)
4
(PO
4
)
2
) exhibits superior selectivity and activity for CO
2
RR to C
2
H
4
. The Faradaic efficiency of C
2
H
4
was achieved over 37.4% with the outstanding stability. The unique structure and morphology characteristics endow Cu
5
(OH)
4
(PO
4
)
2
with more hydroxyl groups (− OH) and higher catalytic area. It affords the high CO
2
RR performance by not only increasing the interaction between the catalysts and CO
2
molecules, but also providing more active sites for CO
2
RR. This work provides a new perspective for the design of stable novel Cu-based catalysts with tunable chemical environment for CO
2
RR.
Owing to a stable and porous cage structure, natural gas hydrates can store abundant methane and serve as a potentially natural gas resource. However, the microscopic mechanism of how hydrate ...crystalline grows has not been fully explored, especially for the structure containing different guest molecules. Hence, we adopt density functional theory (DFT) to investigate the fusion process of structure I hydrates with CH4/C2H6 guest molecules from mono-cages to triple-cages. We find that the volume of guest molecules affects the stabilities of large (51262, L) and small (512, s) cages, which are prone to capture C2H6 and CH4, respectively. Mixed double cages (small cage and large cage) with the mixed guest molecules have the highest stability and fusion energy. The triangular triple cages exhibit superior stability because of the three shared faces, and the triangular mixed triple cages (large-small-large) structure with the mixed guest molecules shows the highest stability and fusion energy in the triple-cage fusion process. These results can provide theoretical insights into the growth mechanism of hydrates with other mono/mixed guest molecules for further development and application of these substances.
An advanced electrocatalyst to accelerate the sluggish kinetics of multistep redox reactions and suppress the severe shuttle effects is desirable in Li‐S batteries (LSBs). Phase engineering can ...provide a fascinating way to modulate electronic structures and boost catalytic activity of electrocatalysts. In this study, few‐layered 1T‐MoSe2 nanosheets grown on carbon cloth (1T‐MoSe2/CC) are synthesized and employed as a multifunctional interlayer as well as a catalytic 3D current collector in LSBs to promote both physiochemical confinement and catalytic conversion toward lithium polysulfides (LiPSs). Density functional theory (DFT) calculations reveal that 1T‐MoSe2 has metallic properties beneficial for rapid electronic transport and exhibits a superior catalytic activity to reduce the Gibbs free energy barriers toward LiPS conversion. Significant improvements in chemisorption toward LiPSs, diffusion coefficients of Li ions, and Li2S deposition/decomposition reaction kinetics are realized by the 1T‐MoSe2/CC film. Consequently, the Al@S/AB@1T‐MoSe2/CC LSB, where 1T‐MoSe2/CC is used an interlayer, presents high rate capability of 1253 (1C), 1052 (2C) and 882 (4C) mAh g−1 and excellent long‐term cycling stability at a high rate (2000 cycles at 4C) with a low capacity fading rate (0.017% per cycle). Moreover, with a sandwiched cathode of 1T‐MoSe2/CC@S/AB@1T‐MoSe2/CC, where 1T‐MoSe2/CC works as both a catalytic 3D current collector and a multifunctional interlayer, the LSB at high S loading of 5.7 mg cm−2 and low electrolyte/sulfur ratio of 7.8 μL mg−1 exhibits a high initial areal capacity of 5.43 mAh cm−2 and remarkable rate‐cycling performance (200 cycles).
Metallic 1T‐MoSe2 grown on carbon cloth (1T‐MoSe2/CC) is fabricated to work as catalytic current collector and multifunctional interlayer for high‐performance lithium‐sulfur batteries. Advanced sandwiched cathode is designed to promote the physical encapsulation, chemical entrapment and catalytic conversion of polysulfide species to suppress the shuttle effect.
Fe acts as the active site and Cu acts as the activity promoter to improve Fe activity in Cu/Fe–NC for higher CO2 reduction reaction performance to multi-electron C1 products.
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...•Dual-atom center enhances the multi-electron pathways for CO2 RR.•Cu/Fe‒NC exhibits low limiting potentials for multi-electron C1 products.•The synergistic effect of Cu/Fe can improve Fe atom catalytic activity.•Dual-atom regulation is conducive to design high atomically dispersed electrocatalysts.
Single-atom catalysts (SACs) are promising electrocatalysts for CO2 reduction reaction (CO2RR) due to the maximal atomic utilization and high catalytic activity. However, most reported SACs tend to convert CO2 to CO or HCOOH rather than other multi-electron C1 products. Here, Taking the regular Fe single-atom catalyst (Fe-NC) as a probe, our study revealed that the construction of dual-atom center through additional Cu (Cu/Fe-NC) allowed for CO2RR proceeding via multi-electron pathways to generate CH3OH and CH4 by means of density functional theory. Cu/Fe-NC exhibited low limiting potentials of −0.42, −0.51, and −0.51 V for HCOOH, CH3OH, and CH4, respectively, while a high limiting potential of −1.18 V for CO. In CO2RR process, using the synergistic effect, Fe acts as the active site and Cu acts as the activity promoter to improve Fe activity for stronger adsorption ability, which promotes the generation of multi-electron products. Hence, the Cu, Fe dual-atom center might provide better catalytic site than regular Fe single-atom center in CO2RR. This work demonstrated Cu/Fe-NC as a high performance CO2RR catalyst to multi-electron products, which will guide more experimental research in high atomically dispersed electrocatalysts to promote CO2RR to high economic value products.
Dual‐metal‐atom‐center catalysts (DACs) are a novel frontier in oxygen electrocatalysis, boasting functional and electronic synergies between contiguous metal centers and higher catalytic activities ...than single‐atom‐center catalysts. However, the definition and catalytic mechanism of DACs configurations remain unclear. Here, a “pre‐constrained metal twins” strategy is proposed to prepare contiguous FeN4 and CoN4 DACs with homogeneous conformations embedded in a N‐doped graphitic carbon (FeCo‐DACs/NC). A programmable phthalocyanines dimer is used as a structural moiety to anchor the bimetallic sites (containing Co and Fe) in a metal–organic framework (MOF) to achieve delocalized dispersion before pyrolysis. The resultant FeCo‐DACs/NC exhibits excellent electrochemical performance in oxygen electrocatalysis and rechargeable Zn–air batteries. Theoretical calculations demonstrate that the synergetic interaction of adjacent metals optimizes the d‐band center position of metal centers and balances the free energy of the *O intermediate, thereby improving the oxygen electrocatalytic activity. This work opens up an avenue for the rational design of DACs with tailored electronic structures and uniform geometric configurations.
A “pre‐constrained metal twin” strategy is presented for the first time to prepare dual‐metal‐atom‐center catalysts (FeCo‐DACs/NC) with continuous FeN4 and CoN4. The FeCo‐DACs/NC delivers excellent catalytic activity in oxygen evolution reaction, oxygen reduction reaction, and Zn–air batteries. The synergistic effect between the two metals optimizes the free energy of the oxygen intermediate state, resulting in improved performance.
Although nanozyme-based colorimetric assays have been broadly used for biosensing, some limitations such as low catalytic activity of nanozyme, poor sensitivity to analytes and lack of understanding ...the structure-activity relationship remain unsolved. In this work, we developed an ultrasensitive colorimetric method for biothiols detection based on density functional theory-assisted design of janus Pd–Fe3O4 nanozyme. The Pd–Fe3O4 dumbbell-like nanoparticles (DBNPs) prepared by seed-mediated approach shows a uniform heterodimeric nanostructure. Ultrasensitive biothiols detection is achieved from two aspects. On one hand, due to the synergistic effect between Pd and Fe3O4 in the dumbbell structure, Pd–Fe3O4 DBNPs show enhanced peroxidase-mimic activity compared to the individual components. On the other hand, when the target biothiols molecule is present, its inhibition effect on the janus Pd–Fe3O4 nanozyme is also significantly enhanced. The above results are confirmed both in experiment and theoretical calculation. Based on the rational design, a simple, highly selective and urtrasensitive colorimetric and quantitative assay for biothiols is developed. The limit of detection (LOD) can reach as low as 3.1 nM in aqueous solution. This assay is also successfully applied to the detection of biothiols in real urine samples. Moreover, the Pd–Fe3O4 nanozyme is used to discriminate biothiols levels in normal and cancer cells with high sensitivity at the cell density of 15,000/mL, which demonstrates its great potential in biological and clinical analysis. This work not only shows the great promise of janus bimetallic nanozymes’ excellent functionalities but also provides rational guidelines to design high-performance nanozymes for biosensing and biomedical applications.
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•The Pd–Fe3O4 janus nanozyme prepared by seed-mediated approach shows a uniform heterodimeric nanostructure.•Pd–Fe3O4 janus nanozyme show enhanced peroxidase-mimic activity compared to the individual components.•The inhibition effect of target biothiols on the janus Pd–Fe3O4 nanozyme is also significantly enhanced.•An effective, ultrasensitive, and selective colorimetric sensor was established for biothiols.
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•A tandem atomically dispersed metal catalyst model is innovatively proposed.•Tandem atomically dispersed metal catalysts can promote flow-line ECO2RR.•The activity-promoting effects ...of tandem catalyst are elucidated.•The challenges, opportunities, and further development of tandem atomically dispersed metal catalysts are discussed.
Atomically dispersed metal catalysts (ADMCs), featuring attractive electronic/geometric configuration and excellent catalytic performance, have emerged a novel class of heterogenous catalysts. However, the linear limitations of ADMCs for complex catalytic reactions, such as the electrocatalytic carbon dioxide reduction reaction (ECO2RR) for C2+ products, constrain the further improvement of the catalytic performance. Hence, we proposed a tandem ADMCs (T-ADMCs) model for the first time, which is inspired by the tandem catalysis observed in the multienzyme catalytic cycles of biocatalytic systems. The coupled multistep reactions occurring at the adjacent sites in T-ADMCs may promote flow-line ECO2RR and optimize the overall catalytic performance. This perspective overviews the recent research advances on T-ADMCs for ECO2RR and highlights the advancing orientation of T-ADMCs. Reaction mechanisms based on CO, formic acid, and acetaldehyde intermediates on T-ADMCs are proposed. The activity-promoting effects of tandem catalyst are elucidated, including the regulation of electronic structure via long-range interaction, breaking of linear scaling relationship, and modulation of local microenvironment through intralayer or interlayer diffusion. The challenges, opportunities, and further development of T-ADMCs and reaction mechanisms under realistic electrocatalytic environment are proposed. This work sheds new light on the design of high-performance T-ADMCs.
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