A facile and simple fabrication of Zn-doped α-Fe<sub>2</sub>O<sub>3</sub> thin films as a photocathode for solar hydrogen generation was proposed in this report. Transparent Zn-doped α-Fe<sub>2</sub>O<sub>3</sub> films were prepared by a deposition-annealing (DA) process using nontoxic iron(III) chloride as the Fe precursor and zinc chloride as a acceptor dopant, followed by annealing at 550 °C in air. In terms of the structural examination of as-grown samples, X-ray diffraction analysis demonstrated an increase in the lattice parameters of Zn incorporated in Fe<sub>2</sub>O<sub>3</sub> by substituting Fe in the host lattice. No second phase was determined, indicating no phase separation in the ternary materials. Energy dispersive spectroscopy results demonstrated that Zn, Fe, and O elements existed in the deposits. Furthermore, impedance measurements show that the Zn-dopant serves as an hole acceptor and increases the acceptor concentration by increasing concentration of zinc precursor. Significantly, the photoelectrochemical measurements exhibited remarkable cathodic current, corresponding to the reduction reaction of hydrogen. Finally, the optimum photocurrent can be achieved by controlled variation of the Fe and Zni precursor concentration, annealing conditions, and the number of DA cycles. According to our investigation, the understandings of morphology effect on PEC activity give the blueprint for materials design in the application of solar hydrogen.
Surface plasmon resonance (SPR) is one of the main mechanisms of Surface Raman Enhance Scattering (SERS) and it will depend on the morphology and free carrier density of substrates, in many of discussions have been proved. Recently, the semiconductor copper(I) sulphide (Cu2S), the natural p-type semiconductor, exhibits remarkable SPR in the nearinfrared region<sup></sup> and can be regards as best candidate for active SERS substrates. In this report, the successive ionic layer adsorption and reaction (SILAR) process will be used to synthesis Cu<sub>2</sub>S nanostructures<sup></sup> from ZnO nanorods as template deposited by electrochemical reaction. To further manipulate the different carrier densities of Cu<sub>2</sub>S nanostructuress, the adjustment of Cu vacancy in Cu<sub>2</sub>S can be accomplished by thermal processes under noble gas. Taking 4-aminothiophenol (4-ATP) as probe molecule to measure the SERS performance by Cu<sub>2</sub>S nanostructures made in this fabrication and also examines the effect on SERS by adjusting Cu vacancy under an excited wavelength of 632.8 nm and light power of 15 mW. In fact, the modulation of Cu vacancy will positively correlate to the SPR frequencies and so could get the best enhancement factor under the limited condition of excited source. Therefore, our results could provide a new opportunity to use SERS to explore the molecule-semiconductor interaction, a fundamental but essential question for designing novel devices.