Semiconductor nanostructures for light-driven chemical reactions

Abstract

Looking at the current energy consumption globally, there is a high demand in the consumption of fossil fuels. Fossil fuels are non-renewable energy sources and they inflict detrimental effects to the environment. As such, it is important to look for alternative yet renewable energy source, which can be achieved using photocatalytic water splitting to produce hydrogen. However, a major problem would be developing a highly efficient photocatalyst to enhance photocatalytic efficiency to maximize hydrogen production. A possible photocatalyst would be Fe3O4-based semiconductor catalyst, as it exhibits superior magnetic properties and is recyclable. Unfortunately, it has limited photocatalytic performance due to its very small band gap that can result in fast electron-hole recombination rate. Hence, modification such as designing core-shell structured nanostructures to enhance photocatalytic efficiency. In this research, the effectiveness of Fe3O4-based semiconductor catalyst was studied by coating a layer of titania onto Fe3O4 that could possibly enhance photocatalytic efficiency for light-driven chemical reactions such as hydrogen evolution reaction. The Fe3O4@TiO2 photocatalyst was characterized using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), solar simulator, gas chromatography (GC), transmission electron microscope (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible spectroscopy (UV-Vis). From the photocatalysis process, small amount of TiO2 layer was coated onto Fe3O4 through mixed solvent and solvothermal method, where 2.4ml concentration of TTIP-IPA heated at 200oC for 20 hours was synthesized. Hence, Fe3O4@TiO2 core-shell nanostructures substantially enhanced photocatalytic efficiency, as well as exhibiting fast magnetic separation and recyclable feature.