Metal–organic frameworks (MOFs) and relative structures with uniform micro/mesoporous structures have shown important applications in various fields. This paper reports the synthesis of unprecedented mesoporous NixCo3−xO4 nanorods with tuned composition from the Co/Ni bimetallic MOF precursor. The Co/Ni‐MOFs are prepared by a one‐step facile microwave‐assisted solvothermal method rather than surface metallic cation exchange on the preformed one‐metal MOF template, therefore displaying very uniform distribution of two species and high structural integrity. The obtained mesoporous Ni0.3Co2.7O4 nanorod delivers a larger‐than‐theoretical reversible capacity of 1410 mAh g−1 after 200 repetitive cycles at a small current of 100 mA g−1 with an excellent high‐rate capability for lithium‐ion batteries. Large reversible capacities of 812 and 656 mAh g−1 can also be retained after 500 cycles at large currents of 2 and 5 A g−1, respectively. These outstanding electrochemical performances of the ternary metal oxide have been mainly attributed to its interconnected nanoparticle‐integrated mesoporous nanorod structure and the synergistic effect of two active metal oxide components.
Although
strain engineering is effective in boosting the activities
of noble metal catalysts, it remains desirable to construct fully
strained catalysts to push the activity to even higher levels. Herein,
we report a novel route to strong lattice strains of a Pd-based catalyst
by radial growth of a Pd-rich phase on Au–Ag alloy nanowires
that are no thicker than 1.5 nm. It creates not only tensile strains
in the Pd-rich sheath due to the core–sheath lattice mismatch
but also distortion and twinning of the lattice, producing nonhomogeneous
local strains as hotspots for the catalysis. Toward the electrochemical
oxidation of biomass-derived alcohols including ethanol, ethylene
glycol, and glycerol, the highly strained nanowires outperformed their
less strained counterparts and reached up to 13.6, 18.2, and 11.1
A mgPd
–1, respectively. This strain engineering
strategy may open new avenues to highly efficient catalysts for direct
alcohol fuel cells and many other applications.
In this work, the core‐shelled Sb@Sb2O3 heterostructure encapsulated in 3D N‐doped carbon hollow‐spheres is fabricated by spray‐drying combined with heat treatment. The novel core‐shelled heterostructures of Sb@Sb2O3 possess a mass of heterointerfaces, which formed spontaneously at the core‐shell contact via annealing oxidation and can promote the rapid Na+/K+ transfer. The density functional theory calculations revealed the mechanism and significance of Na/K‐storage for the core‐shelled Sb@Sb2O3 heterostructure, which validated that the coupling between the high‐conductivity of Sb and the stability of Sb2O3 can relieve the shortcomings of the individual building blocks, thereby enhancing the Na/K‐storage capacity. Furthermore, the core‐shell structure embedded in the 3D carbon framework with robust structure can further increase the electrode mechanical strength and thus buffer the severe volume changes upon cycling. As a result, such composite architecture exhibited a high specific capacity of ≈573 mA h g−1 for sodium‐ion battery (SIB) anode and ≈474 mA h g−1 for potassium‐ion battery (PIB) anode at 100 mA g−1, and superior rate performance (302 mA h g−1 at 30 A g−1 for SIB anode, while 239 mA h g−1 at 5 A g−1 for PIB anode).
CoS and NiS nanomaterials anchored on reduced graphene oxide (rGO) sheets, synthesized via combination of hydrothermal with sulfidation process, are studied as high-capacity anode materials for the reversible lithium storage. The obtained CoS nanofibers and NiS nanoparticles are uniformly dispersed on rGO sheets without aggregation, forming the sheet-on-sheet composite structure. Such nanoarchitecture can not only facilitate ion/electron transport along the interfaces, but also effectively prevent metal-sulfide nanomaterials aggregation during the lithium reactions. Both the rGO-supported CoS nanofibers (NFs) and NiS nanoparticles (NPs) show superior lithium storage performance. In particular, the CoS NFs-rGO electrodes deliver the discharge capacity as high as 939 mA h g(-1) after the 100th cycle at 100 mA g(-1) with Coulombic efficiency above 98%. This strategy for construction of such composite structure can also synthesize other metal-sulfide-rGO nanomaterials for high-capacity lithium-ion batteries.
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