Table I.

EIS parameters associated with different surface modifications of SPCE electrode.

WE	EIS fit model	Goodness of fit	Electrical parameters	Equivalent circuit
bare SPCE	CPE + diffusion (Warburg)	9.3 *10−3	Rs = 120.3 Ω
			Rct = 13.9 kΩ
			CPE = 0.26*10−6 S*sɑ
			ɑ = 0.97
			Wd = 60.2*10−6 S*s1/2
SPCE	CPE	3.9 *10−3	Rs = 127.2 Ω
+ 5% Nafion			Rct = 471.4 kΩ
			CPE = 1.27*10−6 S*sɑ
			ɑ = 0.89
SPCE	CPE	1.4 *10−3	Rs = 122 Ω
+ 5% Nafion			Rct = 257 kΩ
+ 5 mg mL−1 M−1C−1			CPE = 21.04*10−6 S*sɑ
			ɑ = 0.94