Hello Dear Neville James Cory.

How you have selected that Potential range for CV analysis? Have you used Pourbaix (E-pH) diagram of Ti-H2O system. (I have attached here for your reference).

If you see the X-axis of your CV curve, it starts from 0 to +Ve direction [ 0 V to 0.8 V], no negative direction, similarly observed current (Y-Axis) is also showing +ve current peaks no negative current peaks observed. It indicates that, accord to Pourbaix diagram, you have selected only oxidation (anodic) region from 0 to 0.8, that showing species state, Cu + and Cu ++.

According to my little understand, the CV curve is showing only one oxidation (anodic) peak at 2 point. And the point 1 is not reduction peak.

Is it possible to repeat the test by extending the potential range from cathodic (-ve V) to anodic (+ve V) potential range by using Pourbaix diagram or any suitable E-pH diagram according to your study.

Thank you.

Hi Muhammad Ali Siddiqui ,

Thank you for your response.

I have selected the potential window (0-0.8V) based on the glucose oxidation potential from previously reported CuO electrodes which occurs around +0.6V vs Ag/AgCl.

The CV starts at 0V and increases in the (+ve) direction until 0.8V and then reverses direction (-ve) from 0.8V back down to 0V. I used the red arrow to indicate the peak shifts for the forward (anodic) scan with increasing scan rate. The reverse (cathodic) scan first goes through point 1 and then point 2 before reaching the starting 0V potential.

I agree that point 1 is not a reduction peak for the Cu(x) or Cu-hydroxide species though is it at all possible that it could be linked to some desorption process of the oxidized glucose? If point 2 is indeed an oxidation peak why does it appear on the cathodic scan?

I did have a look at the E-pH diagrams for my system and there is a possibility of having a Cu(I) phase though Raman data obtained for samples which had been tested in this solution for 50 cycles showed no Cu(I) peaks only Cu(II).

Thanks.

Most welcome dear Neville James Cory,

Please, find enclosed the attached papers. It will help you to analyze the reversibility criteria.

Regarding, to check the anodic peak and its conjugate cathodic peak, I suggest you to do CV at the same scan rate e.g. 300mV/s with multiple cycle (more than 10 times).

If the current and voltage moved towards higher values, that indicates an effect on the oxide layer thickness and conductivity.

You may check film thickness and conductivity of the film via impedance (EIS) analysis combination with CV, after every reverse scan... like CV+EIS+CV+EIS.

Thanks

Hi Muhammad Ali Siddiqui ,

Thank you for these papers, they are a very interesting read.

Prior to obtaining the CV's I posted, I ran 10 stabilization CV cycles to ensure that the film was stable at 100mV/s within the same potential window. There were no drastic peak spikes or shifts during these cycles.

I will certainly have a closer look at my EIS results to assess the changes in conductivity. I really like this idea of running CV-EIS-CV-EIS. It will elucidate interesting charge transfer characteristics.

Thanks