Morphological and structural control of pulse electrodeposited ZnO thin films and its influence on the photoelectrocatalytic degradation of methyl orange

ZnO thin films were obtained by pulsed electrodeposition (PE). A potential of − 1.1 V is applied during the time-On (ton) period, while open-circuit potential is applied during the time-off (toff) period. The effect of the toff duration on the properties of ZnO films and their photoelectrocatalytic activity was studied in detail. Decreasing toff from 7 s to 1 s tailors the structural, morphological and optical properties of ZnO films and improves their photoelectrocatalytic activity. XRD analysis confirms a wurzite hexagonal structure along the (002) direction for all samples. The SEM images show an amelioration of ZnO morphology from nanosheets to nanorods films. The photocurrent response indicates a high value of 480 µA/cm2 for ZnO film deposited at toff = 1 s. All the electrodeposited films were tested for the photoelectrocatalytic degradation of methyl orange (MO). The ZnO film deposited at low toff (1 s) reveals a faster degradation of MO, reaching 67% after 360 min UV-irradiation. This is attributed to the nano-rod morphology that provides greater surface area and to the lower energy band-gap of the sample.