NH 4 + preintercalated V 2 O 5 •nH 2 O nanobelts with a large interlayer distance of 10.9 Å were prepared by the hydrothermal method. The material showed a large specific capacity of 391 mA•h•g −1 at the 500 mA•g −1 current density in aqueous rechargeable zinc batteries. In operando synchrotron X-ray diffraction demonstrated that the material experienced reversible solid−solution reaction and two-phase transition during charge− discharge cycling, accompanied by the reversible formation/ decomposition of a ZnSO 4 Zn 3 (OH) 6 •5H 2 O byproduct. In operando X-ray absorption spectroscopy confirmed the reversible reduction/ oxidation of V, together with small changes in the VO 6 local structure. The formation of byproduct was attributed to the dehydration of [Zn(H 2 O) 6 ] 2+ , which concurrently improved the desolvation of [Zn(H 2 O) 6 ] 2+ into Zn 2+ . Bond valence sum map analysis and electrochemical impedance spectroscopy demonstrated that the byproduct improved the charge transfer kinetics of the electrode. Cyclic voltammetry and galvanostatic intermittent titration technique showed that the electrode reaction was dominated by ionic intercalation where the discharge capacity in the voltage window of 1.4−0.85 V was attributed to the intercalation of [Zn(H 2 O) 6 ] 2+ , followed by the intercalation of Zn 2+ at 0.85−0.4 V.
A simple, efficient approach for the loading of Ag nanoparticles on poly(dopamine)-modified TiO2 nanotubes was used to prepare a Ag nanoparticle–poly(dopamine)–TiO2 nanotube composite that was applied as a long-term antibacterial agent to inhibit the growth of bacteria.
Magnesium ion batteries (MIBs) have
attracted increasing attention
due to their advantages of abundant reserves, low price, and high
volumetric capacity. However, the large Coulombic interactions of
Mg2+ with the cathode framework seriously hinder the rate
capability and cycle stability of the battery cell. For this reason,
finding a suitable cathode material has become a main task in MIB
research. In this study, Ni3Se4 was first proposed
as a new cathode material for MIBs. First-principles calculations
showed that Ni3Se4 could accommodate up to 1
mol of Mg2+, but the migration energy barrier was as high
as 1.35 eV. Accordingly, nanosized Ni3Se4 was
prepared by a hydrothermal method to achieve satisfying electrochemical
performance. The prepared Ni3Se4 material showed
a discharge capacity of 99.8 mA·h·g–1 at
50 mA·g–1 current density with a capacity retention
of 75% after 100 cycles. Combined with first-principles calculations
and spectroscopic studies, it was demonstrated that the material underwent
a solid-solution structural change during Mg2+ insertion,
with all charge transfer taking place on the Ni cations.
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