I have recently synthesized TiO2 nanorod thin films on FTO glass using hydrothermal methods. I have observed some unusual behavior in a few of these samples. Specifically, when measuring LSV repeatedly in sequence, the current increased, despite all experimental conditions being constant.

I am curious to understand what might be causing this and whether anyone else has observed similar behavior, not necessarily with TiO2, but with other photoactive materials. I am writing to hear from experts in photocatalysts, semiconductors, electrochemistry, and photoelectrochemistry for their professional explanations and insights.

I should mention that this behavior was not observed in all of my samples, only a few of them.

The LSV plot is attached for your reference.