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Abstract Ordered hierarchical structured films are considered promising photoanodes for high-performance water-splitting because of their large surface area for light absorption and excellent charge transfer process. In this paper, a novel hierarchical structured photoanode based on growing TiO 2 on a Si nanowire substrate and coupling with Fe 2 O 3 nanothorns was designed and fabricated via a simple method to obtain photoelectrochemical (PEC) properties. The Fe 2 O 3 /TiO 2 /Si nanowire arrays (NWs) were characterized in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectra. The 3D Fe 2 O 3 /TiO 2 /Si hierarchical photoanode exhibited a photocurrent density of 3.5 mA cm−2 at a bias potential of 1.23 V (vs. RHE), which is approximately 87.5 times higher than that of the Si nanowire array (NW) photoanode. The measurement results showed that the improved PEC performance could be attributed to the synergistic effect of the large surface area, low charge transfer resistance, and high charge separation in the hierarchical structure. Highlights • A novel 3D hierarchical Fe 2 O 3 /TiO 2 /Si photoanode was designed and fabricated. • The structural and morphological properties of Fe 2 O 3 /TiO 2 /Si were characterized. • The Fe 2 O 3 /TiO 2 /Si exhibited much higher photocurrent density than that of Si NWs. • EIS was conducted to investigate the properties of the charge transfer process. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the transport properties of silicon nanowires coated with zinc sulfide nanoparticles. Silicon nanowires were prepared by metal assisted electro-less chemical etching technique. The diameter of nanowires varies from 30 to 300nm and length was ∼30μm. Zinc sulfide nanoparticles having diameter ∼30nm were synthesized by co-precipitation method. The nanoparticles were then deposited between the nanowire arrays and most of the nanoparticles stick to the surfaces of the nanowires. The JV characteristics of the devices were investigated from 77 to 300K. The JV characteristics were nonlinear and asymmetric. The decrease in current density in n-silicon nanowires while increase in current density in p + -silicon nanowires were observed when zinc sulfide nanoparticles were coated on them. The decrease in the current density due to the presence of nanoparticles on the walls of the n-silicon nanowires is attributed to enhancement of trapped charge carriers at zinc sulfide nanoparticles and nanowire interface. However increased hole current was observed due to the formation of acceptor like states on the surfaces of p + -silicon nanowires when nanoparticles were coated on them. The detailed carriers transport mechanisms were studied in both types of silicon nanowires. With back to back Schottky diode, Schottky emission mechanism was observed in p + -silicon nanowires while unusual space charge limited current with and without traps was observed in n-silicon nanowires. [Copyright &y& Elsevier]