ALD-based hydrothermal facile synthesis of a dense WO3@TiO2–Fe2O3 nanodendrite array with enhanced photoelectrochemical properties

Abstract

Hierarchical heterostructured photoanodes have been considered as ideal candidates for oxidation in an effort to enhance the photoelectrochemical (PEC) performance. In this study, well-defined WO₃@TiO₂–Fe₂O₃ nanodendrite arrays composed of WO₃@TiO₂ core–shell nanosheets and Fe₂O₃ nanorods are synthesized by atomic layer deposition and a subsequent hydrothermal process. The growth of Fe₂O₃ nanorods on the surface of WO₃@TiO₂ is demonstrated to be an effective strategy to improve the active surface area and charge separation, which have been proved by the band structure analysis and electrochemical characterization. Particularly, the photocurrent density of the WO₃@TiO₂–Fe₂O₃ nanodendrite array with an 11 nm-thick TiO₂ buffer layer (∼1.92 mA cm⁻²) is much higher than the photocurrent density of the WO₃ photoanode (∼0.41 mA cm⁻²) at 1.23 V vs. RHE in 0.5 M Na₂SO₄ aqueous solutions (pH = 6.8), with outstanding long-term stability as well. This remarkable improvement that comes from rational compositional and structural design of the WO₃@TiO₂–Fe₂O₃ nanodendrite array may provide much inspiration for the development of heterostructured PEC electrodes and devices with novel properties.