Hi,
I am looking forward to calculate area of my Pt electrode which I have modified and used in 3 electrode system for glucose solution in NaOH estimation.
What I did is
As per Randles–Sevcik equation:
ip= 268600n(3/2)AD(1/2)Cv(1/2)
I took value for ip as peak current for my 8mM solution
D obtained from slope of ip vs. square root of v
C as 8mM
v as scan rate
and calculate area as 0.002E-6
I would like to know if I did correct or not?
Further, I divided this area to slope of amperometric calibration curve to obtain sensitivity
Is it correct?
The dynamic surface area of the sensing platform was calculated
by using Randles - Sevcik equation; area was investigated utilizing
cyclic voltammetric technique, 1.0 mM K3Fe (CN)6 as a test solution
and 0.1 MKCl as supporting electrolyte, at different sweep rates,
At T = 298 K and for a reversible process the equation is as follows:
Ip = 2.69×105 x n3/2 AD0 x1/2ν1/2C0
The area of the electrode surface is signified as A, the diffusion
coefficient as D0, i.e. 7.6 × 10−6 cm2 s−1, sweep rate as ν, and C0
is the concentration of K3Fe (CN) 6. From the slope of the plot of Ip
vs. ν1/2, the surface area of the bare electrode was found to be 0.042
cm2 and for the modified electrode, the calculated surface area was
0.36 cm2.
Go through the articles Journal of The Electrochemical Society 164 (5), B3036-B3042 2017; Sensors and Actuators B: Chemical 247, 858-867 2017; Sensors and Actuators B: Chemical 230, 140-148 2017
Thanks Nagaraj for your supportive docs.
As your calculation says, D you got from literature. I would like to know that I calculated D from slope of ip vs sq root of scan rate and used this value in Randles - Sevcik equation to caluclate area. Is this correct?
Hi,
With Randles-Sevcik equation you can obtain D or you can obtain A (or C, n....) but only one! You cannot calculate D from the slope and then the area. In the slope of the curve i-v1/2 you have to include the area, and then it cannot be the unknown at the same time. I would use one taken from the bibliography.
Best regards,
Teresa
Varun Kumar Singh The Value of n is nothing but the oxidation of the ferricyanide, which gives 1 electron and reversible. so the n value is 1
[Fe(CN)6]4− ⇌ [Fe(CN)6]3− + e−
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