Sodium–sulfur batteries using abundant elements offer an attractive alternative to currently used batteries, but they need better sulfur host materials to compete with lithium-ion batteries in capacity and cyclability. We report an in situ sulfur-doping strategy to functionalize MXene nanosheets by introducing heteroatomic sulfur into the MXene structure form the MAX phase precursor. By employing the vacuum freeze-drying method, a three-dimensional (3D) wrinkled MXene nanoarchitecture with the high specific surface area was prepared. The tailor-made wrinkled sulfur-doped MXene (S–Ti3C2T x ) nanosheets were applied as an electrode host material in room temperature sodium–sulfur batteries. The S–Ti3C2T x matrix shows high polarity with sodium polysulfides, restricting the diffusion of sodium polysulfides. The MXene/sulfur electrode can achieve high areal sulfur loading up to 4.5 mg cm–2 as well as good electrochemical performance (reversible capacity of 577 mAh g–1 at 2 C after 500 cycles).
Lithium–sulfur (Li–S) batteries have been regarded as one of the most promising candidates for next-generation energy storage owing to their high energy density and low cost. However, the practical deployment of Li–S batteries has been largely impeded by the low conductivity of sulfur, the shuttle effect of polysulfides, and the low areal sulfur loading. Herein, we report the synthesis of uniform Co–Fe mixed metal phosphide (Co–Fe–P) nanocubes with highly interconnected-pore architecture to overcome the main bottlenecks of Li–S batteries. With the highly interconnected-pore architecture, inherently metallic conductivity, and polar characteristic, the Co–Fe–P nanocubes not only offer sufficient electrical contact to the insulating sulfur for high sulfur utilization and fast redox reaction kinetics but also provide abundant adsorption sites for trapping and catalyzing the conversion of lithium polysulfides to suppress the shuttle effect, which is verified by both the comprehensive experiments and density functional theory calculations. As a result, the sulfur-loaded Co–Fe–P (S@Co–Fe–P) nanocubes delivered a high discharge capacity of 1243 mAh g–1 at 0.1 C and excellent cycling stability for 500 cycles with an average capacity decay rate of only 0.043% per cycle at 1 C. Furthermore, the S@Co–Fe–P electrode showed a high areal capacity of 4.6 mAh cm–2 with superior stability when the sulfur loading was increased to 5.5 mg cm–2. More impressively, the prototype soft-package Li–S batteries based on S@Co–Fe–P cathodes also exhibited superior cycling stability with great flexibility, demonstrating their great potential for practical applications.
Facing the increasingly serious energy and environmental crisis, the development of heteronuclear metal-free doubleatom catalysts is a potential strategy to realize efficient catalytic nitrogen reduction with low energy consumption and no pollution because it could combine the advantages of flexible active sites in double-atom catalysts while also being pollution-free and have high Faraday efficiency in metal-free catalysts simultaneously. However, according to the existing mechanism, the finite orbits of other nonmetallic atoms, except the boron atom, reduce the possibility of metal-free catalysis and hinder the development of heteronuclear metal-free double-atom catalysts. Herein, we propose a new "capture-backdonation-recapture" mechanism, which skillfully uses the electron capture-backdonation-recapture between boron, the substrate, and other nonmetallic elements to solve the above problems. Based on this mechanism, by means of the first-principle calculations, the material structure, adsorption energy, catalytic activity, and selectivity of 36 catalysts are systematically investigated to evaluate their catalytic performance. B−Si@BP1 and B−Si@BP3 are selected for their good catalytic performance and low limiting potentials of −0.14 and −0.10 V, respectively. Meanwhile, the "capture-backdonation-recapture" mechanism is also verified by analyzing the results of adsorption energy and electron transfer. Our work broadens the ideas and lays the theoretical foundation for the development of heteronuclear metal-free double-atom catalysts in the future.
Potassium-ion batteries have attracted attention because of their abundant resources and similar electrochemistry to Li-ion batteries (LIBs). In the present work, GeSe/black phosphorus (BP) heterostructures as promising anode materials for K-ion batteries (KIBs) have been systematically investigated by first-principles calculations. The results reveal that GeSe/BP exhibits a semiconductor-to-metal transition after incorporating K atoms, indicating enhanced conductivity compared to monolayer GeSe. The energy barrier for K atom diffusion on GeSe/BP surface is relatively lower than that on monolayer GeSe. In addition, the GeSe/BP heterostructure can accommodate up to five layers of K atoms with negative adsorption energy, which greatly improves the storage capacity. Hence, the GeSe/BP heterostructure has great potential for application in advanced electrode materials in KIBs.
We propose a conceptual design of InSe/g-C3N4 van der Waals heterostructure to achieve highly efficient and spontaneous water splitting. InSe/g-C3N4 possesses a direct band gap of 2.04 eV with type-II band alignment, which is beneficial to the separation of electrons and holes and exhibits proper valence and conduction-band positions for the redox reactions of H2O. In addition, the adsorption of multiple water molecules and the changes of free energy on InSe/g-C3N4 have been calculated to understand the oxygen evolution reaction (OER) process of water splitting. The free energies of reaction on three sides are all downhill, and the values of ΔG reduce to about −0.406 eV, indicating that the OER of water splitting is a thermodynamically permissible reaction without the aid of any other substance. Therefore, the water-splitting reaction could be thermodynamically continued using InSe/g-C3N4 as a photocatalyst, which indicates that InSe/g-C3N4 is an excellent candidate for photocatalyst or photoelectronic applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.