Figure 3. SEM images: (a) Cu-MOFs; (b)ZIF-9(Co); (c) Cu-Co-2;
(d)Cu-P; (e)Co-P and (f) Cu-Co-2P-2.
Cu-Co-2P-2 composite photocatalyst was tested by TEM characterization to
further understand the morphology and microstructure of the catalyst.
Figure
4(a) and Figure S2(a, b) show the TEM images of Cu-Co-2P-2 composites at
different magnifications, respectively. The results showed that Cu-P-2
and broken Cu-MOFs skeletons existed in the Cu-Co-2P-2 sample when
Cu-MOFs was not completely phosphated, and obvious transparent
sheet-like Co-P appeared on the edges [30]. In addition, the HRTEM
image of the Cu-Co-2P-2 composite is shown in Figure 4(b). Cu-MOFs is
perfectly combined with Co-MOFs phosphatium phospholipids, and the
lattice fringes of Cu3P and CoP can be observed. The
lattice spacings of 0.25 nm and 0.24 nm correspond to the (112) and
(111) crystal planes of Cu3P and CoP, respectively. The
existence of Cu (200) crystal plane can be also observed, and its
lattice spacing is 0.18 nm. EDX results show that Cu-Co-2P-2 composites
contain Cu, Co and P elements (Figure 4(c)). According to XRD analysis,
it can be seen that Cu-Co-2P-2 composites obtained after phosphating of
Cu-Co-2 samples mainly exist in the form of Cu3P and
CoP. At the same time, the electron diffraction (SAED) pattern of
Cu-Co-2P-2 (Figure 4(d)) shows the relatively high crystalline
characteristics of the composite sample. Figure 4(e) is a map of
Cu-Co-2P-2, in which the elements of Cu, Co, and P are evenly
distributed. This shows that the phosphating of Cu-MOFs@ZIF-9(Co) was
successful.