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Much appreciated, glad you enjoyed it!

I think what is hard to know for me to pass judgment on your experiments are the distinct differences between your two types of tests - LSV (potentiostatic) and GCD (galvanostatic). Since they both involve different modes of potentiostat operation, I think it might be tough to make direct comparisons. For instance, in your LSV you are not observing what you believe is substantial water splitting until a certain potential, but you are controlling the potential. With GCD, you are controlling current, so it may not be a perfectly direct comparison since the pairs of i and E you observe in each experiment may not match up the same. As well, to my knowledge, titanium electrochemistry is kind of complex and involves passive film formation and maybe oxides or other kinds of phenomena, and it might be that these processes are occurring in different ways for LSV vs GCD, such that the water splitting you are looking for is convoluted by other electrochemical processes depending on whether you are operating galvanostatically or potentiostatically. Apart from this general thought, probably I would need to see the data to be able to draw any other conclusions for you.

I would need to know more about the system you are studying to be able to answer that question. If you have 3 semicircles that you are fitting with 3 (RC)s, presumably there are 3 distinct processes occurring in your system, and each (RC) should be applied to one of those processes. Every R in those (RC)s is representative of the charge transfer resistance associated with that particular process, but again which processes they are will depend on what your system under study is.

I am doing EIS analysis of the coating on ti alloy and perfectly fit was found with (R3C3) (R2C2)(R1C1)series with RS. Then my question is which is Rct , Cdl, what is Rp value, kindly elaborate me

I have seen all your vidio about the basic s of the eis, find more helpfull,

@@kamalyadav437 First, I must tell you that I will not be able to elaborate fully on your data because rather obviously, I do not have access to your data and your experimental system. There is only so much I can assume from just text. I am not extremely familiar with Ti or Ti alloy electrochemistry, though from what I recall it does tend to form a kind of passivation layer in solution and under polarization, so my best guess is there may be some kind of complex surface film/passivation layer forming on the metal surface during your experiment, and the various RCs you are observing might have to do with a few different interfaces that have formed as a consequence. However, it is also notable to mention that systems like this are notoriously tricky and at times the EIS data itself can be fundamentally inaccurate. For this reason, you should be in the routine of performing Kramers-Kronig analysis on the EIS data to make sure it is valid. It is possible some of the features you believe are additional RCs are just noise or invalid EIS completely.

Thank you very much, I am glad you enjoyed the video! We can certainly add a bipot operation to our ideas for possible content in the future, though to be honest the explanation of bipotentiostat operation is considerably more complicated than even the potentiostat is, and the schematic we use to describe a potentiostat here is already very simplified for educational purposes. To be blunt, I am not sure how easy or understandable it would be to simplify a bipotentiostat schematic and operation. But we appreciate the suggestion and we will keep it in mind for sure!

Thank you kindly!

Thank you! It takes a lot of work trying to make these videos. Some people, Some people, Some people call it insane, yeah they call it insane.

Thank you sir!!

Glad it was helpful! Thank you!

I would ask, is the flow cell active when you take chronoamperometry (CA) experiments? You want the solution to be very still when performing CA. How frequently are the "heart beat" fluctuations occurring? Also, how long are you taking chronoamperometry experiments for and what are you trying to measure?

@@Pineresearch I am measuring the CO2 Reduction reaction products which are release at specific potential ,each batch are tested for 1 hour then i increase the potential for next testing(0.7 -1.3 V vs RHE testing window)which is applied during CA,Yes flow cell is active during whole CA experiment,frequency is very high at higher potential

@@behrozkhan3179 ​ Just to clarify, the potentials you mentioned (0.7 - 1.3 V) vs RHE, I assume those are negative potentials, and when you say "higher potentials" you are referring to higher negative potentials. If you are running CA for 1 hour, one thing to note is how often are you sampling? If you are sampling quickly, every 100 millisecond, then you are going to capture a lot of noise and processes that are occurring during those time scales. You also will generate too many data points (36,000 data points). But if you are sampling at a lower rate (1 data point every 1 second --> 3,600 data points) you might observe a different amount of noise or recurring "heart beat" signals. All that being said, it's hard to diagnose the issue without seeing the CA data, but I hope this helps.

@@Pineresearch I can send you the data but don't know where to send it.Yes sampling rate is 0.1V/s . anyway thanks a lot for your kind help.

@@behrozkhan3179 You can email us at pinewire@pineresearch.com. Mention that you've been talking with Alex via CZcams, and we can continue our conversation via email.

Thank you!!

We can definitely talk about this on the next livestream! Episode #53

Glad you liked it!! :D

Actually there are a few decently Arduino build your own potentiostat papers out there. I don't know if they use the same circuit as this one, but they do exist.

Without seeing your data to know for certain, my best educated guess is to tell you that no, you should not use these LSV data to make a Tafel plot and calculate the Tafel slope. As I mentioned in this episode, the Tafel equation and slope are derived directly from the Butler-Volmer equation, which is an equation that describes exclusively kinetic information, including current. There is no purely kinetic current-time or current-potential curve that results in a peak. The fact that you are observing a peak essentially and fundamentally disqualifies the data, at least in its entirety over that potential range, from being used for Tafel analysis. Regarding your second question, there is basically no difference between CV and LSV. A CV is just two or more LSVs performed back to back.

In the video at 1:27:28 you can see in small font the error statistic for the K-K analysis. There are 3 tabs above the error statistic (small and a little hard to see in the video), those other tabs have fit and measured data, which is the extrapolated K-K data. I hope this was helpful.

Extrapolation from Kramers-Kronig analysis is both unnecessary and, to a certain degree, inappropriate. Kramers-Kronig provides an indication whether your EIS data are valid - that is, linear, causal, and stable. It is not strictly a circuit fit, nor is it a type of analysis designed to extrapolate EIS data. If you are instead performing a circuit fit (after running K-K to determine if the data is properly valid first), then it is perhaps reasonable to see semicircles extrapolated as a visualization of what the data would look like at lower frequencies, for instance. But from K-K analysis this is not needed and does not really provide any useful information.

Out 5-part EIS webinar series is general for EIS and can be useful for anybody trying to learn EIS regardless of the potentiostat they use. For parts of the webinar that go over circuit fitting, we will be using Pine Research's AfterMath software to perform the circuit fitting. But you can use other software to perform circuit fitting. I hope this was helpful.

@@Pineresearch thank you so much

I think that means you like it.

The software download should be free, you just need to create an account which is also free. If you didn't create an account and log in, then you won't be able to download the software.

@@Pineresearch Thank you very much. Is there an option in the software to calculate the Tafel slope from CA and also calculate ECSA? I would appreciate it if you could refer me to the instructional videos you have.

@@parastoomouchani2888 AfterMath does have tools that allow you to calculate Tafel slopes and calculate ECSA, however it's not a simple button press to get that calculation. You would need to do some manipulation of the data and us things like the baseline and area tools to determine things like the Tafel slope and ECSA. We don't have an exact video on performing these calculations but we do a livestream on Friday's at 1 pm EST where you can ask us anything about electrochemistry and we will try to answer your question.

@@Pineresearch Thank you for the quick response. It sounds great. I'll definitely participate.

You're welcome!

@@Pineresearch My expression of thanks may be brief, but please know that I genuinely thank you from the depths of my heart. I sincerely hope that you receive the recognition and rewards you deserve. Thank you so very much.

@@kumu2024 This is very kind of you to say, thank you so much! We are most gratified when people find our videos helpful and watch them, so from the depths of our hearts as well, we appreciate your support and kindness :)

Thanks for your comment. The purpose of this specific video is a more general overview of the concept, but I agree it could be helpful to have more practical applications as well. Likely a webinar would be a useful method for exploring real-world situations, which we have done (though not as frequently with things like CV). You can check out our Webinars playlist to see if there is anything in there of interest to you.

Great, thanks so much for your comment and I'm glad it was helpful!

Sure, if you would like to email us you may do so at pinewire@pineresearch.com

To be honest, I am not sure how best to answer your question without knowing (or seeing) the physical cell setup you have constructed and are using. Almost certainly EIS can be used for measuring conductivity, but your results might have something to do with your cell setup and the data are convoluted as a result. Also, I think it is not guaranteed you should see a semicircle, depending on what your EIS parameters are. In general here, there are a lot of additional details that would be needed to be able to effectively pass judgment on your situation.

It probably depends exactly which experiments you are doing. But one of the impacts of KOH concentration is that the pH will change, and potential shifts at a rate of roughly -60 mV per pH unit. For something as concentrated as 6M KOH, the pH is 14 or even above, though to be honest I am not sure at that level of alkaline the measurement of pH continues to be perfectly accurate. But for instance, if you went to something like 0.1M KOH, the pH would be approximately 13, so in this example if you went from pH 14 to 13, theoretically any features electrochemically would shift in potential positively by about 60 mV. Apart from that, there could be other effects from changing the electrolyte concentration but I would need to know more about the specifics of the experiments being done. And ultimately, the best answer to this question is to simply change the concentration yourself, run the experiments, and see what happens (if anything).

@@Pineresearch i am running experiments of three electrode system in which my electrode is a nickel foam coated with transition metal oxide and sulfide based nanocomposite..and for this experiment i am using 6M KOH electrolyte solution..

@@yumnakhan4914 I think the answer to what will happen by changing KOH concentration in your experiment is the same as I mentioned previously, which is that you just need to try it and see what happens, if anything. I imagine you have a good reason for wanting to adjust the electrolyte concentration, so you may likely need to run the experiments yourself and see how it affects results.

Much appreciated!

Thanks for your question. Unfortunately, I don't have very much experience with lithium leaching experiments, and it also seems like your question is somewhat broad. For instance, it is not clear what "appropriate curve" means. As well, have you looked into the scientific literature to see what lithium leaching curves and experiments other researchers have done? Typically this is a good place to start when finding the parameters to apply with your research.

@@Pineresearch thank you so much. greetings.

Glad to hear it, I am happy my answers were useful for you!

This is a good question. First, I will just tell you I have added this question to be answered during our next livestream, which as of this comment will be Friday, April 19 2024 at 1pm EST. I encourage you to join or watch the replay (it will be episode #49 of Ask Us Anything About Electrochemistry). As far as a quick answer, it honestly depends. For a multi-layered electrode, theoretically every single interface (substrate/film, film 1/film 2, film 2/electrolyte, etc) can result in a unique impedance response. But this is not a guarantee. And as it relates to Warburg diffusional impedance, it is just tricky because you may not know what is diffusing, how far, and into which layers. For instance, there is likely diffusion in the electrolyte, but is there also diffusion through the outermost layer? The second layer too? Every layer? And you may only be able to resolve each of these phenomena if they happen to occur at different timescales, which is also not a guarantee and if this is the case, you might get sort of an aggregate diffusional measurement that cannot be easily resolved into the component parts specific to each layer in your electrode structure.

@@Pineresearch I will definitely catch the livestream. I would like to expand on my query (just to clarify it better with regard to the circuit). If, in a substrate/film1/film2/electrolyte multilayer coating scenario, the EIS circuit is given as R1+Q1/R2+Q2/R3, would the Warburg element be included so as to reframe the circuit as R1+Q1/(R2+W1)+Q2/R3 or as R1+Q1/(R2+W1)+Q2/(R3+W2)? Thank you for explaining the possible multi-diffusion happening across the layers, never thought about that. I will definitely catch the stream and am eager to learn more. Thank you again.

@@devxpentatom7932 Thanks for the follow up. I understand your question. In short, I would not anticipate adding a separate Warburg embedded within BOTH Randles interfaces to be accurate (or even likely to be physically occurring). Additionally, I think you're missing a Randles element representative of the last film/electrolyte interface. I will try to illustrate this tomorrow during the livestream for you.

Oh no, I'm sorry to hear that! But I am glad you enjoyed our video anyway!

I am not sure how to succinctly answer your question. Are you trying to figure out how to make proper experimental measurements? How to construct a fuel cell or electrolyzer? How to perform circuit fitting? There are a lot of possible things you might be asking and I do not know what you are asking about specifically. If you want to elaborate on your question, I encourage you to join our weekly livestream on Fridays at 1pm EST and you can ask questions, then we will try to answer them live for you.

Thank you!

Indeed yes! No efforts have gone to waste with all your past gaming!

Our pleasure!

Glad you enjoyed it!

I can only speak on behalf of Pine Research, but our AfterMath software performs K-K analysis to validate your EIS data. If you are using another potentiostat you can important your data to AfterMath, and there is an option to perform K-K. Then you can look at how well the fit is and the chi-squared value to see if you EIS data is valid. You can download AfterMath for free and use our circuit fitting and K-K analysis tools. All you need to do is create a free account on our website. pineresearch.com/shop/knowledge-category/downloads/

Thank you so much. Please help me with another query. What is the acceptable chi-squared value for EIS data in KK analysis. I have EIS data that gives 0.0008 chisq value. Is the data valid?

@@yeasmins074 The problem with judging a fit by chi squared is that there is not an easy universal metric to gauge whether it is good or bad. Whether you are doing circuit fit or K-K analysis, chi squared should generally be used as a comparison across multiple analyses on the same data. For K-K in particular, it is both quantitative through chi squared but also extremely subjective. You may have to determine for yourself how closely the fit appears to match your data and make a determination from there. You may also find, for instance, some frequencies fit better than others. Sometimes the low frequency points don't match as well because of drift, but the mid to high frequency points do, so you can propose most of your data are valid but the lower frequencies are less accurate. But overall, it is not simple to give a set universal chi squared metric for saying definitively something like "larger = bad, smaller = good"

Thank you for the response ❤.

Glucose by itself isn't electroactive, so you wouldn't observe an oxidation or reduction currents associated with glucose. However, some of the original technology for electrochemical glucose sensors was using the enzyme glucose oxidase that converted glucose and oxygen to gluconic acid and hydrogen peroxide. The hydrogen peroxide was electroactive on platinum electrodes. Today I believe there are more advanced technologies for electrochemical glucose detection.

This is a good question, we will address this question in episode #47 of the Ask us Anything about Electrochemistry livestream.

@@Pineresearch Thankyou so much fo the reply.I watched the session.Is there any way to contact you for more queries regarding electrochemistry.Email id ?

You should email pinewire@pineresearch.com, but the livestream is the best place for us to discuss technical questions.

You're very welcome, glad you enjoyed it!

Thanks for your question. Typically, CV is not the most preferred technique to use on batteries. In a recent livestream I talked about this a little bit, see this link for some additional context: czcams.com/users/liveZb36oDPMW8A?si=BkIYVqvenOJyYXMx&t=2062 If you want more live, detailed discussion of this subject or others related to batteries, I invite you join one of our weekly livestreams on Fridays at 1pm EST (US eastern time). You can ask questions and I will try to address them live for you.

@@Pineresearch Thanks for your reply.

Unfortunately, we don't have a video on ACV. That's a topic I need to do a lot more research into to make a good video on it.

çox sağ ol

Very good question. We will spend some time on the next livestream to discuss this.

Thank you, glad you enjoyed it!

Glad you enjoyed it!

Ferro/ferricyanide is soluble in water and I would assume that your enzymetic electrodes are also stable in water. Additionally I am assuming that the ferro/ferricyanide is sold with a potassium cation (potassium ferrocyanide). As such, I might recommend using an aqueous electrolyte of KCl for studying your system. Also, your buffer solution might also be a good candidate as an electrolyte. I hope this was helpful.

This question was actually answered during this Livestream, here is the link to the specific time stamp: czcams.com/users/liveMfuLwQ5uGdI?si=4f78fWTqT7RbvS4j&t=6009

Thanks