Metal-doped cobalt spinel oxides are considered to be
effective
materials to improve the oxygen reduction reaction (ORR) performance.
However, the doping sites of nickel in Co3O4 spinel (octahedral sites or tetrahedral sites) remain controversial,
leading to a poor understanding of the effects of nickel. Herein,
directionally introducing nickel into the octahedral sites of Co3O4 (Ni
Oh
-Co3O4) is proposed by exploiting the different
redox capabilities of different nickel sources, which yields an encouraging
ORR and rechargeable Zn–air battery performance. Magnetic measurements
and theoretical calculations reveal that the nickel occupied at the
octahedral site can effectively promote the spin-state transition
from low spin to higher spin states for cobalt ions and the hybridization
of Co 3d–O 2p electrons, resulting in the optimization of the
adsorption strength for the oxygen intermediates, thus improving the
oxygen catalytic activity of Ni
Oh
-Co3O4.
Mitochondria are
crucial in the process of oxidative metabolism
and apoptosis. Their morphology is greatly associated with the development
of certain diseases. For specific and long-term imaging of mitochondrial
morphology, we synthesized a new mitochondria-targeted near-infrared
(NIR) fluorescent probe (TPE–Xan–In) by incorporating
TPE with a NIR merocyanine skeleton (Xan–In). TPE–Xan–In
displayed both absorption (660 nm) and emission peaks (743 nm) in
the NIR region. Moreover, it showed aggregation-induced emission properties
at neutral pH and specifically illuminated mitochondria with good
biocompatibility, superior photostability, and high tolerance to mitochondrial
membrane potential changes. With a pH-responsive unit, hydroxyl xanthene
(Xan), the probe exhibited a pH-sensitive fluorescence emission in
the range of pH 4.0–7.0, which indicated its potential in long-term
tracking of pH and morphology changes of mitochondria in the biomedical
research studies.
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