Study of anodic behavior of tungsten in methanesulfonic acid by voltammetric, electrochemical impedance, and photoelectrochemical methods

Kinetics of the galvanostatic formation of anodic oxide films (AOF) are stu died on tungsten electrode in methanesulfonic acid solutions. The process i s shown to follow general regularities of the AOF formation on tungsten in acidic electrolytes. The electrical field intensity in the AOF formation an d the anodizing constant are determined. Impedance spectroscopy and photoel ectrochemistry of AOF formed preliminarily show that the differential capac itance of AOF and photocurrents generated in them vary with potential in pa rallel. At potentials close to the formation potential E-f, AOF behave as d ielectric films. When potential decreases to values close to the oxide's fl at band potential E-fb, a transition to regularities typical for semiconduc tors is observed. For semiconducting tungsten oxide formed in methanesulfon ic acid, E-fb and the band gap are determined.