I have noticed a recent phenomenon while testing various materials as catalysts for CO2 reduction. Regardless of how much I increase the voltage, I have observed that the current cannot exceed a specific value. This limitation seems to depend on the electrolyte and its concentration. I doubted that this current limit was due to mass transfer constraints. However, if that were the case, the cyclic voltammetry (CV) plot should show a smooth approach towards the limiting current, rather than an abrupt cut-off configuration as I have observed.
Prior to realizing the electrolyte effect, I considered the possibility that the potentiostat (CHI660D) was responsible for this limitation, with the current exceeding its capability. However, this cannot be the case, as the limit is influenced by the electrolyte. Some members of my research group have suggested adjusting the sensitivity in the potentiostat's software, but I have already set it to the highest sensitivity (1e-1), resulting in the highest current limit.
I am seeking an explanation for this current limit and possible ways to overcome it.
Scrubbing my last answer. You do seem to be in a hardware limit, but not the system limit, possibly an issue with IE range not setting/changing correctly. It could be you are running up against a compliance limit, which would explain the higher current limit you see in the higher ionic strength solution.
The potentiostat imposes the limit. I mean, your equipment can not measure higher currents.
Try to modify the geometry of your working electrode, or use another potentiostat with higher current limits that ovoid the over current.
Or you could use your actual equipment but include a booster.
Best Wishes!
I agree, but how can you explain this limit change with different electrolyte solutions or concentrations?(the limit is 30 mA with 0.1 M KHCO3 corresponding to the attached picture and 100mA with 0.5 M)
How could this be related to the potentiostat?
Nowadays, the only way that I get around it is, as you mentioned, by reducing the electrode/electrolyte interfaces.
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