I have synthesized Co9S8/graphene nancomposite. I have measured CV of nanocomposites using three-electrode method in 6 M KOH. But I am getting very very low current and hence the Cs value. Also, I am not getting any pseudo peak of Co9S8 also. Do I need to change the electrolyte?? Please suggest.
Yes, you should vary the electrolyte and concentration to get maximum specific specific capacitance for supercapacitor electrode. Test in only one electrolyte is not a good idea. The procedure has been briefly described in the supporting part of my publication.
Thats not the matter whether you are getting pseudo peak or not. If you are not getting oxidation-reduction peaks, you should not confuse whether the material is pseudocapacitie or not. CVs dissimilar from EDLC derived rectangular shapes always add some pseudocapacitive or reversible redox behavior. Moreover electrode can include both EDLC and pseudocapacitive charge storage behavior, you can calculate the percentage as well. Go through my publications. I have calculated and described briefly. I think it will clear your concept. I have attached another paper, it can help you as well.
https://www.nature.com/articles/srep43430
http://jes.ecsdl.org/content/162/5/A5185.full
Data V2O5 encapsulated MWCNTs in 2D surface architecture: Complet...
Thank you very much for your answer and references. I am bit confuse for the electrolyte, because every existing literature on such kind of composite used varied concentration of KOH as a electrolyte and obtained the capacitance value between 800 - 1200 F/g. But I am getting extremely low capacitance value, thats why i was wondering. Even though i have also used varied concentration of KOH.
There is a good chance that it is the sampling mode of the potentiostat you are using. If you want good capacitance measurement you need to either be using a surface mode sampling technique with a digital staircase or an analog scan generating system. Conventional digital staircase sampling collects the current point at the end of the step and the current from double layer capacitance and adsorbed species has decayed by then. This is great if you are measuring CV of some electroactive species that is diffusing to the surface, as it enhances signal to noise. For EDLCs and adsorbed species, however, you tend to get much lower current than you should.
By either sampling across the whole step (and averaging) or by using an analog scan, you can capture the correct total amount of current from the double layer capacitance as well as for adsorbed species.
In other research articles, authors synthesize electrode material with different techniques. So, the morphology, surface area, porosity of the materials are different for each though the active material is same. So, favourable electrolyte for the same material synthesized by others can be different, concentration too. You should go for all the electrolyte variation, and pick the best one. then concentration as I've done in my publications. that's the standard method.
check the electrolyte and then concentration, may be you can get higher capacitance. and getting low capacitance is not the issue. Journals mainly prefer ur novel ideas and concepts, not high/low value. I have attached some papers. Authors report current value in µA, and published in higher impact journals.
so, forget about others. Do your own experimental variations and report ur results.
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