Layered transition metal sulfides (LTMSs) have tremendous commercial potential in anode materials for sodium‐ion batteries (SIBs) in large‐scale energy storage application. However, it is a great challenge for most LTMS electrodes to have long cycling life and high‐rate capability due to their larger volume expansion and the formation of soluble polysulfide intermediates caused by the conversion reaction. Herein, layered CuS microspheres with tunable interlayer space and pore volumes are reported through a cost‐effective interaction method using a cationic surfactant of cetyltrimethyl ammonium bromide (CTAB). The CuS–CTAB microsphere as an anode for SIBs reveals a high reversible capacity of 684.6 mAh g−1 at 0.1 A g−1, and 312.5 mAh g−1 at 10 A g−1 after 1000 cycles with high capacity retention of 90.6%. The excellent electrochemical performance is attributed to the unique structure of this material, and a high pseudocapacitive contribution ensures its high‐rate performance. Moreover, in situ X‐ray diffraction is applied to investigate their sodium storage mechanism. It is found that the long chain CTAB in the CuS provides buffer space, traps polysulfides, and restrains the further growth of Cu particles during the conversion reaction process that ensure the long cycling stability and high reversibility of the electrode material.
Emerging
sodium-ion batteries (SIBs) have aroused great attention
in large-scale energy storage. However, it is still a great challenge
to develop suitable electrode materials due to the large radius of
Na+. This work demonstrates a strategy to synthesize hierarchical
tubular MoS2
via a facial hydrothermal
method with the assistance of tetramethylammonium bromide (TMAB).
The results show that sufficient amounts of TMA+ ions are
necessary to form the hierarchical tubular structures of MoS2. The obtained tubular MoS2 displays a high diffusion
coefficient of Na+ ions, a high specific capacity of 652.5
mAh/g at the current density of 100 mA/g after 50 cycles, and a good
cycling stability (94.2% of the initial capacity can be retained after
100 cycles at 1000 mA/g). In situ XRD during the
discharge/charge process displays a reversible intercalation/deintercalation
of Na+ into MoS2 layers followed by a conversion-type
reaction. Systematic analyses reveal that the enhanced electrochemical
performance is attributed to its tubular hierarchical structures with
the wall composed of loosely stacked nanosheets, which can provide
nearly unobstructed ion transportation paths, sufficient active sites,
and enough space to mitigate the effects of the volume change during
the discharge/charge process. This synthetic approach can be easily
extended to other metal oxides and metal sulfides with hierarchical
structures for versatile applications.
Intercalation chemistry/engineering has been widely investigated in the development of electrochemical energy storage. Graphite, as an old intercalation host, is receiving vigorous attention again via a new halogen intercalation. Whereas, exploiting new intercalation hosts and optimizing the intercalation effect still remains a great challenge. This study fabricates a Cu2Se intercalation compound showing expanded interlayer space and nanosheet array features by using a green growth approach, in which cetyltrimethyl ammonium bromide (CTAB) is inserted into Cu2Se at an ambient temperature. When acting as an electrode material for sodium‐ion batteries, the Cu2Se–CTAB nanosheet arrays exhibit excellent discharge capacity and rate capability (426.0 mAh g−1 at 0.1 A g−1 and 238.1 mAh g−1 at 30 A g−1), as well as high capacity retention of ≈90% at 20 A g−1 after 6500 cycles. Benefiting from the porous array architecture, the transport of electrolytes is facilitated on the surface of Cu2Se nanosheets. In particular, the CTAB intercalated in the interlayer space of Cu2Se can increase its buffer space, stabilize the polyselenide shuttle, and prevent the fast growth of Cu nanoparticles during its electrochemical process.
The clinical employment of cisplatin (cis‐diamminedichloroplatinum(II) (CDDP)) is largely constrained due to the non‐specific delivery and resultant serious systemic toxicity. Small‐sized biocompatible and biodegradable hollow mesoporous organosilica (HMOS) nanoparticles show superior advantages for targeted CDDP delivery but suffer from premature CDDP leakage. Herein, the smart use of a bimetallic Zn2+/Cu2+ co‐doped metal–organic framework (MOF) is made to block the pores of HMOS for preventing potential leakage of CDDP and remarkably increasing the loading capacity of HMOS. Once reaching the acidic tumor microenvironment (TME), the outer MOF can decompose quickly to release CDDP for chemotherapy against cancer. Besides, the concomitant release of dopant Cu2+ can deplete the intracellular glutathione (GSH) for increased toxicity of CDDP as well as catalyzing the decomposition of intratumoral H2O2 into highly toxic •OH for chemodynamic therapy (CDT). Moreover, the substantially reduced GSH can also protect the yielded •OH from scavenging and thus greatly improve the •OH‐based CDT effect. In addition to providing a hybrid HMOS@MOF nanocarrier, this study is also expected to establish a new form of TME‐unlocked nanoformula for highly efficient tumor‐specific GSH‐depletion‐enhanced synergistic chemotherapy/chemodynamic therapy.
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