Pulse electrodeposition of ZnO/SnO2 composite films: Growth mechanism, structural and optical studies

► ZnO/SnO2 composite films were firstly coelectrodeposited. ► The formation mechanism of ZnO/SnO2 composite was proposed. ► The bandgap of ZnO/SnO2 composite films was modulated from 3.20 to 3.44 eV.