Study on copper oxide stability in photoelectrochemical cell composed of nanostructured TiO2 and CuxO electrodes

•Performance of Ti|TiO2| 0.1 M KOH |CuxO|Cu photoelectrochemical cell is investigated.•Recrystallization of nanostructured CuxO layer during photoelectrolysis is observed.•Comprehensive analysis of possible photoelectrochemical reactions is presented.•Factors influencing stability of Cu/CuxO photocathode are discussed.•An important role of H2O2 in operation of PEC is revealed.

In the present study the performance of photoelectrochemical cell composed of nanostructurized CuxO and TiO2 photoelectrodes short-circuited in side by side configuration in 0.1 M KOH is investigated with the purpose to test the stability of Cu/CuxO photocathode. The techniques employed are X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, scanning electron microscopy and voltammetry. Comprehensive analysis of possible electrochemical reactions, involving participation of photogenerated charge carriers is presented. Recrystallization of CuxO layer accompanied by the change in photocathode color is found to occur during the photoelectrolysis. The influence of structural factors, the potential of conjugated electrodes and hydrogen peroxide, which forms as intermediate during photoelectrolysis, on the balance of cathodic reactions and stability of operation of Ti|TiO2 | 0.1 M KOH | CuxO|Cu photoelectrochemical cell is discussed.