Abstract
The development of high-efficiency, robust, and available electrode materials for oxygen evolution reaction (OER) and lithium-ion batteries (LIBs) is critical for clean and sustainable energy system but remains challenging. Herein, a unique yolk-shell structure of Fe2 O3 nanotube@hollow Co9 S8 nanocage@C is rationally prepared. In a prearranged sequence, the fabrication of Fe2 O3 nanotubes is followed by coating of zeolitic imidazolate framework (ZIF-67) layer, chemical etching of ZIF-67 by thioacetamide, and eventual annealing treatment. Benefiting from the hollow structures of Fe2 O3 nanotubes and Co9 S8 nanocages, the conductivity of carbon coating and the synergy effects between different components, the titled sample possesses abundant accessible active sites, favorable electron transfer rate, and exceptional reaction kinetics in the electrocatalysis. As a result, excellent electrocatalytic activity for alkaline OER is achieved, which delivers a low overpotential of 205mV at the current density of 10mA cm-2 along with the Tafel slope of 55mV dec-1 . Moreover, this material exhibits excellent high-rate capability and excellent cycle life when employed as anode material of LIBs. This work provides a novel approach for the design and the construction of multifunctional electrode materials for energy conversion and storage.
Highlights
Introduction architectures for highly efficientoxygen evolution reaction (OER) electrocatalysts and highperformance lithium-ion batteries (LIBs).Serious environmental pollution and energy crisis are Recently, iron-based oxides have been widely studied in the prompting people to focus on renewable and clean ener- fields of energy storage and conversions owing to their high gies, new technologies and devices associated with energy electrochemical activity, rich redox properties, natural abunstorage and conversion systems.[1]
The hierarchical Fe2O3@Ni3Se4 nanotubes prepared by Zheng et al exhibited much better OER and lithium storage performance than the individual Fe2O3 and Ni3Se4.[6]. The enhanced OER electrocatalytic activity was attributed to the short diffusion pathways, sufficient active sites and synergistic effects between the Ni3Se4 and Fe2O3, whereas the improved lithium storage performance was ascribed to the high specific capacity of Fe2O3 and fast electron transportation of Ni3Se4
The flower-like FeS/Fe2O3 composite synthesized by Wang et al manifested higher specific capacity and better cycling stability compared with pure FeS and Fe2O3.[8] cobalt sulfides are promising electrode materials in the fields of electrocatalysis, Li(Na)-ions batteries, sensing, and solar cells, because of their high conductivity and unique physical and chemical properties.[9]
Summary
These results imply that the sample consists Fe2O3 nanotubes, ZIF-67, and a trace amount of carbon-coated Co9S8 (named as Fe2O3@ZIF67@Co9S8@C). Further increasing the amount of TAA to 3 mmol, the SEM and TEM images in Figure 2k,l indicate that some of the external Co9S8 shells break into pieces and the internal Fe2O3 nanotubes are free in space, forming a multiple core–shell structure of Fe2O3 nanotube@cracked-Co9S8 nanocage@C (Fe2O3@c-Co9S8@C). The peak at 168.7 eV can be attributed to the SOx groups formed by the inevitable oxidation of S in the air.[22]
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