Effect of pretreatments on the hydrogen evolution kinetics of pure titanium using impedance and SECM technologies

The behaviors and kinetics of hydrogen evolution reaction (HER) on pure titanium spontaneously passivated in air (P-Ti), activated by electrochemical method (EA-Ti) and fluoride ion (FA-Ti) were investigated by impedance and scanning electrochemical microscopy (SECM). During cathodic polarization, the passive film and proton were simultaneously reduced on P-Ti, only HER current was detected on EA-Ti, while both HER and active/passive transition behavior presented on FA-Ti. Corresponding transfer coefficients and standard rate constants of HER are 0.48/6.00 × 10 −12 cm/s, 0.25/7.60 × 10 −7 cm/s and 0.24/1.14 × 10 −6 cm/s, respectively. These differences originate from the change in electronic structure of passive film by pretreatments.