i repeat an experiment (electrodeposition of polyaniline by cyclic voltammetry ) many times, keeping all its experimental parameters remain same. Each time i obtain different mass of polyaniline deposited on working electrode. i used Gamry Interface 1000 and three electrode configuration (WE is stainless steel, counter electrode is platinum sheet and Ag/AgCl is reference electrode). Aqueous electrolyte solution is 100 ml containing 0.5 M aniline and 0.5 M H2SO4. Aniline is distilled before use (transparent), Double distilled water is used for aqueous solution
Why depostion of PANI mass each time is different , since all experimental parameters and conditions are same. Also, morphology is different and specific capacitance value is randomly changed.
I suggest that the sample preparation for weighting is not reproducible (i.e., drying is not complete).
I would suggest to calculate the charge consumed during CV to correlate with the obtained mass. To add, low molecular weight polymers of PANI deposited could dissolve in the monomer solution. Potentiostatic or galvanostatic treatment could solve your problem.
cheers
@ Cornel Radu, thank you Sir for reply
before weighing, each sample is heated around 80 degree celcius for 15-20 minutes. can heating of sample at 100 degree celcius or above remove/ reduce this problem?
@ Nirmalesh Naveen, thank you sir for reply
How i can calculate charge consumed for 20 CV?
during anodic scan calculated charge is positive (Q') and during cathodic scan calculated charge is negative (-Q''). sum of cathodic charge and anodic charge will give net charge (Q1=Q'-Q'') consumed for a CV. calculating net charge consumed for each cycle and their sum will give total charge (Q= Q1+Q2+.....+Q20) consumed for 20 CV cycles.
I would like to ask here, have you weighed your steel substrate before experiment? Is the quality of steel substrate is good? And what is the size of steel substrate?? how the cutting of steel substrate is done??
Please check these basic parameters. This might be affecting on the mass while deposition of PANI.
Thank you madam @ Anamika Kadam
weight of substrate is measured before and after deposition. also stainless steel is stable within the potential window. electrodeposition is carried out on 1 cm2 area.
If " each sample is heated around 80º Celsius for 15-20 minutes " , water is not completely evaporated.
I suggest:
- to wash the sample in distilled water (to eliminate electrolyte and monomer),
- to keep the sample at 105º C for min. 30 minutes (to completely evaporate water),
before weighing.
If all parameters are same, then try to perform EQCM study of PANI. It will provide a noticeable changes in mass while deposition of PANI.
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