“…The simple electrochemical method is also very convenient for wide applications. 5−12 It is universally acknowledged that simple anodization can enable fabrication of nanostructured oxide layers on the surface of various metals and alloys, such as Al, 6,7 Ti, 8,9 Pb, Co, Zr, 10,11 Ti-2Al-1.5Mn alloy, 12 etc. However, the formation mechanisms of these porous oxides are still controversial.…”