Synthesis of CdSe on FTO-supported ZnO nanorods by SILAR and electrochemical methods and comparison of photoelectrochemical properties of FTO/ZnO/CdSe systems in aqueous S2−/Sn 2− electrolyte

The ZnO nanorods electrochemically deposited on FTO substrate were covered with CdSe by means of two different procedures: successive ionic layer adsorption and reaction (SILAR) and electrochemical pulse methods. The electrodeposition was performed in alkaline solution containing Na2SeSO3 and Cd(NTA)− complex. The number of SILAR cycles and charge density involved in electrodeposition of CdSe were adjusted to obtain the same ZnO loading with light-absorbing semiconductor. Photoelectrochemical properties of these two types of FTO/ZnO/CdSe electrodes in aqueous solution containing S2−/Sn 2− redox couple are compared. The highest photocurrents and open circuit potential values under illumination were obtained for the samples with CdSe deposited in 10 SILAR cycles and electrodeposited at the charge density of 100 mC cm−2. A dependence of the CdSe stoichiometry (determined from EDX spectra) and photoactivity of the both types of ZnO/CdSe composites on the synthesis conditions (number of SILAR cycles, precursor concentration, potential and current density) are discussed.