Material characterization
The morphologies of Zn@Zn2(bim)4 and Zn
deposition after cycling were presented by a field-emission scanning
electron microscope (FESEM, JEOL 7100F) equipped with energy dispersive
spectrometer (EDS, OXFORD X-MAX). The MOF layer was scraped from the in
situ growth, and its 2D structure was characterized using a TEM (JEOL
2010). The crystal structure of the Zn and MOF layer was analyzed by XRD
(PW1825) with Cu K𝛼 radiation. The Raman spectra were carried out with
the InVia (Renishaw) Raman spectrometer with a 633 nm laser as the
excitation source. The Raman for liquid solutions is taken by common
procedures. For MOF decorated electrodes, the
Zn@Zn2(bim)4 electrodes were cycled in
symmetric cells at 0.5 mA cm-2 and 0.5 mAh 10 times,
and the small amount of liquid electrolyte was wiped out using a tissue
before taking the Raman test. The excitation light is focused on the
electrode surface with a depth of less than 1 µm; the power of the laser
beam is adjusted to be 10% of a maximum of 30 mW to avoid damage to the
MOF material. The wettability of bare zinc and
Zn@Zn2(bim)4 were tested by contact
angles measurement (Biolin Theta). The TGA of as-prepared
MnO2/CNT cathode
material was conducted with a thermogravimetric analyzer (Q5000TA) with
a heating rate of 5 ℃ min-1 from 20 to 800 ℃ under
airflow.