Sodium-ion batteries are a potentially low-cost and safe alternative to the prevailing lithium-ion battery technology. However, it is a great challenge to achieve fast charging and high power density ...for most sodium-ion electrodes because of the sluggish sodiation kinetics. Here we demonstrate a high-capacity and high-rate sodium-ion anode based on ultrathin layered tin(II) sulfide nanostructures, in which a maximized extrinsic pseudocapacitance contribution is identified and verified by kinetics analysis. The graphene foam supported tin(II) sulfide nanoarray anode delivers a high reversible capacity of ∼1,100 mAh g(-1) at 30 mA g(-1) and ∼420 mAh g(-1) at 30 A g(-1), which even outperforms its lithium-ion storage performance. The surface-dominated redox reaction rendered by our tailored ultrathin tin(II) sulfide nanostructures may also work in other layered materials for high-performance sodium-ion storage.
Light scattering by small particles has a long and interesting history in physics. Nonetheless, it continues to surprise with new insights and applications. This includes new discoveries, such as ...novel plasmonic effects, as well as exciting theoretical and experimental developments such as optical trapping, anomalous light scattering, optical tweezers, nanospasers, and novel aspects and realizations of Fano resonances. These have led to important new applications, including several ones in the biomedical area and in sensing techniques at the single-molecule level. There are additionally many potential future applications in optical devices and solar energy technologies. Here we review the fundamental aspects of light scattering by small spherical particles, emphasizing the phenomenological treatments and new developments in this field.
Abstract
The grand challenge in the development of atomically dispersed metallic catalysts is their low metal-atom loading density, uncontrollable localization and ambiguous interactions with ...supports, posing difficulty in maximizing their catalytic performance. Here, we achieve an interface catalyst consisting of atomic cobalt array covalently bound to distorted 1T MoS
2
nanosheets (SA Co-D 1T MoS
2
). The phase of MoS
2
transforming from 2H to D-1T, induced by strain from lattice mismatch and formation of Co-S covalent bond between Co and MoS
2
during the assembly, is found to be essential to form the highly active single-atom array catalyst. SA Co-D 1T MoS
2
achieves Pt-like activity toward HER and high long-term stability. Active-site blocking experiment together with density functional theory (DFT) calculations reveal that the superior catalytic behaviour is associated with an ensemble effect via the synergy of Co adatom and S of the D-1T MoS
2
support by tuning hydrogen binding mode at the interface.
There is a great challenge to design anode materials for rechargeable batteries with large capacity, excellent cyclic stability and high rate performance. Using first principle calculations, we have ...calculated electronic properties of monolayer SnS2 which reveal that it is an indirect-gap semiconductor with a band gap of 1.56 eV. The SnS2 becomes metallic after the insertion of small amount of K content, and the electronic conductivity increases by increasing the concentration of K. Also, our predictions show that there is a proper binding energy between K ion and monolayer SnS2 with a low average open circuit voltage (0.84 V) which is in the range of commercial anode materials. The energy surface for the diffusion of K ion on the surface of SnS2 monolayer is analyzed and a very low energy barrier (0.054 eV) is found for the K diffusion. These results indicate that SnS2 is very suitable to be use as a high performance anode material for KIBs.
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•K ions are adsorbed on SnS2 with high concentration which indicates the potential high energy density.•Pristine SnS2 is a an indirect-gap semiconductor with a band gap of 1.56 eV and becomes to be metallic after the insertion of small amount of K content.•For the K ion diffusion on SnS2, the energy barrier is just 0.054 eV.
Transition metal dichalcogenides (TMDs) show wide ranges of electronic properties ranging from semiconducting, semi-metallic to metallic due to their remarkable structural differences. To obtain 2D ...TMDs with specific properties, it is extremely important to develop particular strategies to obtain specific phase structures. Phase engineering is a traditional method to achieve transformation from one phase to another controllably. Control of such transformations enables the control of properties and access to a range of properties, otherwise inaccessible. Then extraordinary structural, electronic and optical properties lead to a broad range of potential applications. In this review, we introduce the various electronic properties of 2D TMDs and their polymorphs, and strategies and mechanisms for phase transitions, and phase transition kinetics. Moreover, the potential applications of 2D TMDs in energy storage and conversion, including electro/photocatalysts, batteries/supercapacitors and electronic devices, are also discussed. Finally, opportunities and challenges are highlighted. This review may further promote the development of TMD phase engineering and shed light on other two-dimensional materials of fundamental interest and with potential ranges of applications.
The diversity of electronic characteristics of TMDs ranging from the semiconducting, semi-metallic to metallic have broadened their application in catalysis, electrode materials and next-generation functional electronic devices.
With first-principles DFT calculations, the interaction between Li and carbon in graphene-based nanostructures is investigated as Li is adsorbed on graphene. It is found that the Li/C ratio of less ...than 1/6 for the single-layer graphene is favorable energetically, which can explain what has been observed in Raman spectrum reported recently. In addition, it is also found that the pristine graphene cannot enhance the diffusion energetics of Li ion. However, the presence of vacancy defects can increase the ratio of Li/C largely. With double-vacancy and higher-order defects, Li ion can diffuse freely in the direction perpendicular to the graphene sheets and hence boost the diffusion energetics to some extent.
We explore the stability, electronic properties, and quantum capacitance of doped/co-doped graphene with B, N, P, and S atoms based on first-principles methods. B, N, P, and S atoms are strongly ...bonded with graphene, and all of the relaxed systems exhibit metallic behavior. While graphene with high surface area can enhance the double-layer capacitance, its low quantum capacitance limits its application in supercapacitors. This is a direct result of the limited density of states near the Dirac point in pristine graphene. We find that the triple N and S doping with single vacancy exhibits a relatively stable structure and high quantum capacitance. It is proposed that they could be used as ideal electrode materials for symmetry supercapacitors. The advantages of some co-doped graphene systems have been demonstrated by calculating quantum capacitance. We find that the N/S and N/P co-doped graphene with single vacancy is suitable for asymmetric supercapacitors. The enhanced quantum capacitance contributes to the formation of localized states near the Dirac point and/or Fermi-level shifts by introducing the dopant and vacancy complex.
Metallic 1T-phase transition metal dichalcogenides (TMDs) are of considerable interest in enhancing catalytic applications due to their abundant active sites and good conductivity. However, the ...unstable nature of 1T-phase TMDs greatly impedes their practical applications. Herein, we developed a new approach for the synthesis of highly stable 1T-phase Au/Pd-MoS2 nanosheets (NSs) through a metal assembly induced ultrastable phase transition for achieving a very high electrocatalytic activity in the hydrogen evolution reaction. The phase transition was evoked by a novel mechanism of lattice-mismatch-induced strain based on density functional theory (DFT) calculations. Raman spectroscopy and transmission electron microscopy (TEM) were used to confirm the phase transition on experimental grounds. A novel heterostructured 1T MoS2–Au/Pd catalyst was designed and synthesized using this mechanism, and the catalyst exhibited a 0 mV onset potential in the hydrogen evolution reaction under light illumination. Therefore, this method can potentially be used to fabricate 1T-phase TMDs with remarkably enhanced activities for different applications.
By the incorporation of C into (BN)12 fullerene, our theoretical investigation shows that the hydrogenation reaction on carbon doped B11N12C cluster is both thermodynamically favored and kinetically ...feasible under ambient conditions. Without using the metal catalyst, the C atom can work as an activation center to dissociate H2 molecule and provide the free H atom for further hydrogenation on the B11N12C fullerene, which saves the materials cost in practical applications for hydrogen storage. Moreover, the material curvature also plays an important role in reducing the activation barrier for the hydrogen dissociation on the BN fullerenes.
► The kinetics of the hydrogenation reaction on C-doped BN fullerene was studied. ► The C atom works as an activation center for the hydrogen dissociation. ► The hydrogenation on C-doped BN fullerene is a metal free and self-catalyzed process. ► C doping can effectively modify the hydrogen storage property of the BN fullerene. ► There is a curvature effect on the hydrogenation kinetics of BN fullerenes.
Understanding the origin of valence band splitting is important because it governs the unique spin and valley physics in few-layer MoS2. We explore the effects of spin–orbit coupling and interlayer ...coupling on few-layer MoS2 using first-principles methods. We find spin–orbit coupling has a major contribution to the valence band splitting at K in multilayer MoS2. In double-layer MoS2, the interlayer coupling leads to the widening of the gap between the already spin–orbit split states. This is also the case for the bands of the K-point in bulk MoS2. In triple-layer MoS2, the strength of interlayer coupling of the spin-up channel becomes different from that of spin-down at K. This combined with spin–orbit coupling results in the band splitting in two main valence bands at K. With the increase of pressure, this phenomenon becomes more obvious with a decrease of main energy gap in the splitting valence bands at the K valley.
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