Fabrication of Mn–ZnO photoanodes for photoelectrochemical water splitting applications

A photoelectrochemical (PEC) water splitting ability of pure ZnO and manganese-incorporated ZnO thin films fabricated via a simple aerosol-assisted chemical vapour deposition (AACVD) method was compared in Na2SO4 electrolyte solution. Optical properties analysis showed the shifting of optical band gap from 3.02 to 2.76 eV as the molar ratio of Mn varies from 0.02 to 0.15. All the compositions of Zn1−xMnxO (x = 0.02 to 0.15) show superior photocurrent density compared to pure ZnO-based photoanodes. The activity of Zn0.85Mn0.15O was found highest with photocurrent density of 3.81 mA/cm2. This activity enhancement was due to the shifting of the optical band gap in the visible region with the increase in absorption intensity. Moreover, the activity is further affected by the growth of uniform and homogeneous structures onto the photoanodes. The morphology of the films and size of crystallites change by varying amounts of Mn into the ZnO films. Overall, this work demonstrates that Zn1−xMnxO has a significant potential for PEC water splitting with further tailoring of their electronic properties.