Hierarchical Co₃Se₄ Nanoparticles Encapsulated in a Nitrogen‐Doped Carbon Framework Intertwined with Carbon Nanotubes as Anode of Li‐Ion Batteries

Abstract

Transition metal selenides (TMSes) are regarded as ideal anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacity, but some defects, such as volume expansion and poor conductivity, still need to be overcome. The design of hierarchical structural materials with compositional and structural complexity is extremely attractive in the field of energy conversion. Herein, a core-shell hierarchical polyhedral Co 3 Se 4 with N-doped and carbon nanotubes intertwined (N-Co 3 Se 4 @C-CNTs) is synthesized using a facile metalorganic framework (MOFs) self-templating strategy and selenization treatment. The Co 3 Se 4 nanoparticles can be confined in the multilocular and hollow carbon framework intertwined with CNTs. Benefiting from the unique structure and composition superiority, the synthesized N-Co 3 Se 4 @C-CNTs exhibit excellent Li storage performance. Specifically, they present a high reversible capacity of 820 mAh g À1 at 0.1 A g À1 after 100 cycles and outstanding cycling stability (558 mAh g À1 at 2 A g À1 after 1000 cycles). In addition, a LiCoO 2 ‖N-Co 3 Se 4 @C-CNT full cell is successfully constructed to show its potential for practical application. The reaction kinetics and Li storage mechanisms of the N-Co 3 Se 4 @C-CNT electrode are investigated to explain the impressive electrochemical performance. This work reveals the great application potential of the N-Co 3 Se 4 @C-CNT electrode in constructing advanced LIBs.

Developing Outstanding Bifunctional Electrocatalysts for Rechargeable Zn‐Air Batteries Using High‐Purity Spinel‐Type ZnCo2Se4 Nanoparticles

“…These peaks appeared to be broad due to the incorporation of a Zn atom with Co 3 Se 4 @rGO, which also caused an increase in the intensity ratio of the D and G bands (I D /I G ) values. [35] The separate peaks in the G band at 1581 cm −1 are related to the sp 2 nature of the catalysts carbon atoms, and the D bands have distinct peaks at 1350 cm −1 , which are attributed to the defective nature of graphitic carbon. The Co 3 Se 4 @ rGO catalyst had an intensity ratio of I D /I G value of about 1.25, which is higher than the ZnCo 2 Se 4 @rGO catalyst (I D /I G = 1.27).…”

“…[38,39] Se 3d XPS spectra showed peaks at 54.3 and 55.6 eV (Figure 2c), corresponding to Se 3d 5/2 and Se 3d 3/2 , respectively, resulting from Co-Se bonds, which shows that the ZnCo 2 Se 4 nanocomposite was successfully formed. [35] Additionally, ZnCo 2 Se 4 @rGO was studied by X-ray absorption spectroscopy (XAS) using reference foils like Zn and Co to determine the best electrocatalysts detailed elemental locations and electronic configuration. As seen in Figure 2d, the XANES spectra describe the coordination environment of the catalysts ZnCo 2 Se 4 @rGO and Co 3 Se 4 @rGO, and the catalysts states were further confirmed by the XANES spectra, showing a distinctive peak at 7710 eV caused by Co 4sp to Co 3d hybridization.…”

Microwave‐Assisted Synthesis of Cobalt‐Based Selenides as Catalyst Precursors for the Alkaline Water Oxidation

“…In panel b, labels show peak assignments based on the literature data. [36,42,[45][46][47][48][49][65][66][67][68] admixture was present in the material synthesized at 200 °C. Hence, the major focus of further characterization studies was on the material obtained at 180 °C.…”

“…[42,43] Specifically, peaks at 184 and 681 cm À1 can be attributed to the A g and A 1g vibration modes of CoSe n , respectively. [42,[44][45][46][47][48] A broader band at 138 cm À1 can be assigned to a E g vibration mode of the Se atoms, while signals at 476, 520, and 611 cm À1 might correspond to the E g , 1F 2g , and 2F 2g modes of CoO x from the partially oxidized surface of the material. [36,[45][46][47]49] Scanning (SEM) and transmission electron microscopy (TEM) imaging of the microwave-synthesized CoSe n suggests that the material represents aggregates ranging in size from dozens to a few hundred nanometers (Figure 2a,b).…”

“…[42,[44][45][46][47][48] A broader band at 138 cm À1 can be assigned to a E g vibration mode of the Se atoms, while signals at 476, 520, and 611 cm À1 might correspond to the E g , 1F 2g , and 2F 2g modes of CoO x from the partially oxidized surface of the material. [36,[45][46][47]49] Scanning (SEM) and transmission electron microscopy (TEM) imaging of the microwave-synthesized CoSe n suggests that the material represents aggregates ranging in size from dozens to a few hundred nanometers (Figure 2a,b). These aggregates comprise small crystallites with clearly defined lattice fringes with an interlayer distance of approximately 0.26-0.27 nm, which is consistent with the (111) plane of the Co 3 Se 4 phase (PDF 04-015-1918).…”