“…Zinc oxide has been widely applied as photocatalysts [ 1 , 2 , 3 , 4 ], antimicrobial agents [ 5 , 6 , 7 ], supercapacitors [ 8 , 9 ], sensors [ 6 , 10 ], varistor [ 11 ], biosensors [ 10 ], in solar cells [ 12 , 13 , 14 ], transparent electrodes [ 15 ], and fuel cells [ 9 , 16 ]. This wide range of applications is based on the characteristics of ZnO as an n-type semiconductor, low-cost, chemical, and thermal stability, a direct band gap (~3.3 eV), and binding energy of 60 meV [ 17 , 18 ].…”