Abstract
Porous ZnO/C nanocomposites derived from 3 different Zinc based metal-organic frameworks (MOFs) including MOF-5, MOF-74, and ZIF-8. The formation mechanism from MOF precursors, the structural properties, morphologies, compositions, and textural properties of the derived ZnO/C composites were fully investigated based on different characterization techniques and the correlation between the precursors and the derived composites was discussed. The PXRD patterns of ZnO derived from MOF-5, MOF-74, and ZIF-8 exhibited highly crystalline wurtzite ZnO structures with main peak (101). The morphological details of the prepared samples were analyzed by SEM and TEM. Both the SEM and TEM micrographs of ZnO/MOF-5, ZnO/MOF-74, and ZnO/ZIF-8 samples clearly display the spherical, nanotubes, and nanosheets, respectively. A considerable red shift in the absorption was found to be pristine ZnO after addition of various MOFs. The optical band gap energies are found to be 3.27, 2.94, and 2.81 eV, for ZnO/MOF-5, ZnO/MOF-74, and ZnO/ZIF-8 samples, respectively. The ZnO/CZIF-8 based DSSC shown a high PCE of 11.2%, which is higher than that of ZnO/CMOF-5 (6.7%) and ZnO/CMOF-74 (8.2%). Importantly, the ZnO-MC electrode exhibits higher catalytic activity for the I-3(-) reduction than the MC electrode. The improved PCE can be referred to at the ZnO photoelectrode/electrolyte interface, the inhibition of charge transfer, whereas the right implementation of MOFs effectively reduces the mutation of charges, as verified by spectra for electrochemical impedance.