Simple solvothermal approach to highly nanostructured hematite thin films

In this work, we present a solvothermal method for the synthesis of hematite thin films on fluorine-doped tin oxide substrates. This simple method uses a precursor solution of iron(III) 2,4-pentanedionate dissolved in ethanol with a microliter-scale amount of water and yields hematite similar to 500 nm thick films after annealing. The synthesized films were characterized using an array of methods, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance, and powder X-ray diffraction. Incorporating water into the precursor solution provides nucleation sites for the reaction and results show that by altering the amount of water used in the synthesis, it is possible to generate nanocrystalline films of different morphologies, nanocrystal size distributions, and surface areas. This synthetic procedure therefore provides control over the films' physical and electrochemical characteristics. Doping of hematite thin films is also possible using this synthesis, as exemplified by doping with tin by adding tin(II) 2,4-pentanedionate to the precursor solution. To demonstrate utility, we build prototype photoelectrochemical cells using the synthesized hematite as the photoanode.

Automated summary

This work presents a solvothermal method for synthesizing hematite thin films on fluorine-doped tin oxide substrates, utilizing a precursor solution of iron(III) 2,4-pentanedionate dissolved in ethanol with a small amount of water. By incorporating water into the solution, nanocrystalline films of hematite with different morphologies, nanocrystal size distributions, and surface areas can be generated, giving control over the films' physical and electrochemical characteristics. Doping of hematite thin films is also achievable using this method, as demonstrated by doping with tin in the precursor solution for building prototype photoelectrochemical cells with the synthesized hematite as the photoanode.