2 research outputs found
Biomimetic Mineralization Guided One-Pot Preparation of Gold Clusters Anchored Two-Dimensional MnO<sub>2</sub> Nanosheets for Fluorometric/Magnetic Bimodal Sensing
A novel
fluorometric/magnetic bimodal sensor is reported based
on gold nanoclusters (Au NCs)-anchored two-dimensional (2D) MnO<sub>2</sub> nanosheets (Au NCs–MnO<sub>2</sub>) that are synthesized
through a one-pot biomimetic mineralization process. Bovine serum
albumin (BSA) was used as the template to guide the formation and
assembly of the Au NCs–MnO<sub>2</sub> under physiological
conditions and without use of any strong oxidizing agent and toxic
surfactants as well as organic solvent. The fluorescence of Au NCs
was first quenched by MnO<sub>2</sub> nanosheets, while upon H<sub>2</sub>O<sub>2</sub> introduction, the MnO<sub>2</sub> nanosheets
can be sensitively and selectively reduced to Mn<sup>2+</sup> with
enhanced magnetic resonance (MR) signal and rapid recovery of Au NCs
fluorescence simultaneously. This dual-modal strategy can overcome
the weakness of a single-fluorescence detection mode. A linear range
of 0.06–2 μM toward H<sub>2</sub>O<sub>2</sub> was obtained
for the fluorescence mode, whereas the MR mode also allowed detection
of H<sub>2</sub>O<sub>2</sub> at a concentration that ranged from
0.01 to 0.2 mM. Benefiting from the BSA molecule residual on the product
surface, the as-prepared Au NCs–MnO<sub>2</sub> displays low
cytotoxicity and good biocompatibility. Importantly, the successful
application of Au NCs–MnO<sub>2</sub> for analysis of H<sub>2</sub>O<sub>2</sub> in biological samples and cells indicates that
the integration of Au NCs fluorescence with Mn<sup>2+</sup> MR response
provides a promising bimodal sensing platform for H<sub>2</sub>O<sub>2</sub> in vivo monitoring
MOF-Templated Fabrication of Hollow Co<sub>4</sub>N@N-Doped Carbon Porous Nanocages with Superior Catalytic Activity
Metallic
Co<sub>4</sub>N catalysts have been considered as one of the most
promising non-noble materials for heterogeneous catalysis because
of their high electrical conductivity, great magnetic property, and
high intrinsic activity. However, the metastable properties seriously
limit their applications for heterogeneous water phase catalysis.
In this work, a novel Co-metal–organic framework (MOF)-derived
hollow porous nanocages (PNCs) composed of metallic Co<sub>4</sub>N and N-doped carbon (NC) were synthesized for the first time. This
hollow three-dimensional (3D) PNC catalyst was synthesized by taking
advantage of Co-MOF as a precursor for fabricating 3D hollow Co<sub>3</sub>O<sub>4</sub>@C PNCs, along with the NH<sub>3</sub> treatment
of Co-oxide frames to promote the in situ conversion of Co-MOF to
Co<sub>4</sub>N@NC PNCs, benefiting from the high intrinsic activity
and electron conductivity of the metallic Co<sub>4</sub>N phase and
the good permeability of the hollow porous nanostructure as well as
the efficient doping of N into the carbon layer. Besides, the covalent
bridge between the active Co<sub>4</sub>N surface and PNC shells also
provides facile pathways for electron and mass transport. The obtained
Co<sub>4</sub>N@NC PNCs exhibit excellent catalytic activity and stability
for 4-nitrophenol reduction in terms of low activation energy (<i>E</i><sub>a</sub> = 23.53 kJ mol<sup>–1</sup>), high
turnover frequency (52.01 × 10<sup>20</sup> molecule g<sup>–1</sup> min<sup>–1</sup>), and high apparent rate constant (<i>k</i><sub>app</sub> = 2.106 min<sup>–1</sup>). Furthermore,
its magnetic property and stable configuration account for the excellent
recyclability of the catalyst. It is hoped that our finding could
pave the way for the construction of other hollow transition metal-based
nitride@NC PNC catalysts for wide applications