Tafel lines charge transfer coefficient

One can determine the charge transfer coefficient from the slope of the Tafel lines and the exchange current density from an extrapolation to the Nemst potential E = Eq. 

The charge transfer coefficients determined from the slope of the Tafel lines were = 0.66 and = 1 — = 0.36. 

Equation (31) is valid for 6 and represents a Tafel equation with a correction term, which takes into account the lowering of concentration due to the rate control by diffusion and reaction, and the reverse reaction [44]. The slope and the extrapolation to / = 0 of the straight lines obtained from equation (31) allows the determination of the charge transfer coefficient, a, and the exchange current density, respectively, without diffusion and reaction rate control. 

Thus, the true charge-transfer current can be calculated from the ordinate at the origin in the plot between the reciprocal of the measured current density, j"1, as a function of w. The slope (B 1) is the reciprocal value of the Levich constant, 0.620nFCJoj, because it is the only portion that strictly depends on the co value [107], where D, is the coefficient of diffusion of they-particle. With the currents corrected from the mass transport effects, we can depict the Tafel lines, from which the values of j0 and a can be calculated. 

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