Controlled growth of 3D CdS-branched ZnO nanorod arrays for efficient solar driven photoelectrochemical water splitting

Abstract

While world energy consumption is rising every year, the development of clean and renewable energy sources becomes very important for keeping the standard of living and preserving the environment. Solar driven photoelectrochemical (PEC) water splitting to produce hydrogen and oxygen is a promising method to contribute to the energy increasing demand. The development of the photoelectrode is a key factor for improving the PEC performance. A new morphology of 3D CdS-branched ZnO nanorod array nanocomposite has successfully been synthesized via solution routes as a photoanode. The present nanocomposite provides the highest photocurrent density of 2.5 mA/cm2 at a potential 1.23 V vs. RHE, which is about 83.3 times compared to a photocurrent density of about 0.03 mA/cm2 of the bare ZnO nanorod array photoelectrode. The boost of the PEC performance is improved due to the improvement of light absorption capacity, the enhanced energy band alignment (type-II heterostructure) promoting the charge transfer and separation, and the improvement of the electrode-electrolyte interface reaction kinetics. The result will be useful for further research on energy conversion and energy storage devices.