Unveiling the Co2+ Ion Doping-Induced Hierarchical Shape Evolution of ZnO: In Correlation with Magnetic and Photovoltaic Performance

A sustainable, rapid microwave-assisted glycothermal (MW-GT) method has been adopted for the synthesis of pristine ZnO and a series of Zn1–xCoxO (x = 0, 0.02, 0.03, 0.05, 0.07, 0.10) within 15 min at 180 °C using ethylene glycol (EG) as solvent. The XRD results reveal that the altering of lattice parameters of ZnO by introduction of Co2+ ions and crystalline sizes of Co2+ doped ZnO samples decreased with increasing Co2+ ion content. A spectacular morphological change of ZnO from well-defined hexagonal prismoid to hierarchical flower-like 1-D nanorods-assembly upon increasing Co2+ ion concentration was perceived using FE-SEM and TEM analyses. After Co2+ ion inclusion into pristine ZnO, the width of the M–H loop significantly changes, where the diamagnetic behavior of ZnO changes from ferromagnetic to paramagnetic upon further increase in Co2+ ion content. Particularly, 5 mol % Co2+ ion doped ZnO sample shows enhanced photovoltaic performance in dye-sensitized solar cells (DSSCs) due to nanoscale level inte...