High‐efficiency sodium storage of Co_0.85Se/WSe₂ encapsulated in N‐doped carbon polyhedron via vacancy and heterojunction engineering

Abstract

With the advantage of fast charge transfer, heterojunction engineering is identified as a viable method to reinforce the anodes' sodium storage performance. Also, vacancies can effectively strengthen the Na+ adsorption ability and provide extra active sites for Na+ adsorption. However, their synchronous engineering is rarely reported. Herein, a hybrid of Co0.85Se/WSe2 heterostructure with Se vacancies and N‐doped carbon polyhedron (CoWSe/NCP) has been fabricated for the first time via a hydrothermal and subsequent selenization strategy. Spherical aberration‐corrected transmission electron microscopy confirms the phase interface of the Co0.85Se/WSe2 heterostructure and the existence of Se vacancies. Density functional theory simulations reveal the accelerated charge transfer and enhanced Na+ adsorption ability, which are contributed by the Co0.85Se/WSe2 heterostructure and Se vacancies, respectively. As expected, the CoWSe/NCP anode in sodium‐ion battery achieves outstanding rate capability (339.6 mAh g−1 at 20 A g−1), outperforming almost all Co/W‐based selenides.

A strongly coupled 3D SnS2@Ti3C2Tx heterojunction with vacancies for high-efficiency sodium storage

“…2b), the peaks located at 162.8, 161.2 eV and 160.7 eV correspond to S 2p 1/2 , S 2p 3/2 and the Ti-S bond, confirming the formation of chemical bonding between SnS 2 and the Ti 3 C 2 T x substrate. Compared with the previously reported binding energy peak of S, 23,32,33 the peaks of S 2p 1/2 , S 2p 3/2 and Ti-S for SnS 2 @Ti 3 C 2 T x move towards the low binding energy region, indicating that binding with Ti 3 C 2 T x increases the electron density of S. The change of binding energy indicates that electron transfer occurs in SnS 2 @Ti 3 C 2 T x , which is due to the strong interaction between SnS 2 and Ti 3 C 2 T x at the heterointerface, leading to electron redistribution and thus regulating the electron structure. Moreover, since Sn is a mixed valence state of Sn 4+ and Sn 2+ , according to the charge compensation mechanism, there are S vacancies in the SnS 2 @Ti 3 C 2 T x heterostructure.…”

“…This shift is attributed to strain and lattice distortions in the crystal caused by the formation of S vacancies. 23,28 When compared to pure Ti 3 C 2 T x (Fig. S1a, ESI†), the (002) diffraction peak of SnS 2 @Ti 3 C 2 T x shifts from 7.9° to 7.8°, indicating the successful modification of SnS 2 onto Ti 3 C 2 T x and expansion of the interlayer spacing within Ti 3 C 2 T x .…”

“…Finally, the charge redistribution at a heterojunction boundary induces the adsorption of sodium ions at more active sites. [21][22][23] For instance, Co-introduced NiS nanorods prepared on Ti 3 C 2 T x MXene nanosheets, arranged in a sandwiched structure, demonstrated enhanced alkali metal ion storage. 24 In a separate study, heterogeneous Ti 3 C 2 T x @S-MCoP (M = Ni, Mn, Zn) composites were designed, which significantly improved sodium storage performance.…”

Sodium Layered/Tunnel Intergrowth Oxide Cathodes: Formation Process, Interlocking Chemistry, and Electrochemical Performance

“…With the increasing energy source demands and the rapid reduction of fossil fuels, the development of renewable and clean energy techniques is especially needed. – Large-scale electrical energy storage systems (EESs) with safety, low-cost, long-life, and environmentally friendly features are essential to satisfy the sustainable development demands of modern society. – Although lithium-ion batteries (LIBs) have been commercially applied in electronic products and daily lives in the past decades, the high cost and limited source of lithium still cause a large barrier to extending their application in EESs. – In this regard, sodium-ion batteries (SIBs) have received great attention as a potential alternative to LIBs based on the abundance of Na resources and its similar storage mechanism to LIBs. – …”

CoFeSe2@DMSA@FA Nanocatalyst for Amplification of Oxidative Stress to Achieve Multimodal Tumor Therapy**

“…This phenomenon might lead to an increase in the number of active sites, so promoting the Fenton-like reaction and ultimately facilitating faster reaction kinetics. [37] The nanocatalyst exhibits glutathione peroxidase-like activity, enabling the consumption of excess glutathione and disrupting the redox balance in tumor cells, consequently inducing apoptosis. Co 3 + ions present in the nanoparticles can utilize a portion of the internal H 2 O 2 to generate O 2 , thus alleviating tumor hypoxia.…”