Electrochemical deposition of cabbage-like lead microstructures on fluorine-doped tin oxide for oxygen sensor application

摘要

Metallic lead (Pb) has been electrodeposited on FTO substrate at room temperature from aqueous nitrate solution under constant applied potential in the range of -0.46 to -0.8V vs. SCE. Cyclic voltammetry shows that 3D nucleation and growth are the main feature at higher electrolyte concentration when the profile is recorded at 20mVs(-1). While a single step potential facilitates the deposition of faceted crystals of Pb, distinguished lead having cabbage-like morphology can be deposited by applying sequential two step potentials. The I-t response shows that the deposition is initiated through instantaneous 2D nucleation and growth at the shorter time domain followed by 3D nucleation and growth in 0.4M Pb(NO3)(2). Theoretical simulation of the closely matched experimental I-t profile for simple step potential provides a 2D rate constant of 2.000.04x10(-7)molcm(-2)s(-1) while for 3D, the vertical and plane growth rate constant of 3.270.05x10(-5)molcm(-2)s(-1) and 2.00 +/- 0.04x10(-7)molcm(-2)s(-1), respectively. The formation of the cabbage morphology has been discussed on the basis of time evaluation of FE-SEM. The high surface area of unique lead deposits with cabbage morphology shows better life time and oxygen sensitivity in a typical oxygen sensor application.