“…Co 3 O 4 in the form of microspheres [34,36], nanoplates and nanobelts [38] have been prepared by hydrothermal processes. Co 3 O 4 NPs were prepared via several methods including solvothermal [32], chemical precipitation [37], pulsed laser deposition (PLD), electron beam deposition, sol-gel techniques [39], and by the thermal decomposition of the [(NH 3 ) 5 Co(O 2 )Co(NH 3 ) 5 ](NO 3 ) 4 ] [40]. In addition, nanosized Co 3 O 4 thin films were also prepared using sol-gel spin coating technique [35].…”