Can the electrochemical cv curve be used if it is not closed?

I don't think so. This may be a problem of leakage current or the device itself.

Extension: CV: Cyclic voltammetry is a commonly used electrochemical research method. In this method, the electrode potential is controlled to repeatedly scan in a triangular waveform at different rates with time, and the potential range enables different reduction and oxidation reactions to occur alternately on the electrode, and the current-potential curve is recorded. According to the shape of the curve, we can judge the reversibility of the electrode reaction, the possibility of adsorption of intermediates and phase boundaries or the formation of new phases, and the nature of the coupling chemical reaction. It is often used to measure electrode reaction parameters, judge its control steps and reaction mechanism, and observe what reactions can occur and their properties in the whole potential scanning range.