“…Several metal elements including Fe, Cr, Ni, Na, Al, Co, Mn, Zn, Mg and V have been used as dopants to modify the physical properties of CuO. 13,22,27,30,35–39 Doping with Ni increases the optical absorption, charge carrier concentration, and photostability of CuO nanostructures. 40 Fe-doped CuO has a slightly higher band gap and electrical conductivity than undoped CuO due to the formation of oxygen vacancies.…”