Reduction of H2O2 at CuInSe2 (Photo)cathodes. II. Sustained and Triggered Oscillations

A region of differential negative resistance appears in the dynamic current/potential curve of H2O2 reduction at p-CuInSe2 (photo)cathodes after appropriate electrochemical treatment. Associated with this feature, oscillatory phenomena may occur: potential oscillations under galvanostatic control and current oscillations under potentiostatic control, in the presence of a suitable external resistance. Oscillations of defined frequency may be obtained by synchronization to a periodic potential or light triggering action. The cell may behave as a rudimentary light sensor responding with individual current/potential pulses to short photon flux interruptions. Qualitative analysis of the oscillatory phenomena is proposed, focused on the conditions of circuit (in)stability, which accounts intuitively for the experimental findings.