Aluminum-α-hematite thin films for photoelectrochemical applications

In recent years, photoelectrochemical (PEC) based devices have become attractive due to production of hydrogen by splitting water using photocatalyst alpha (α)-hematite (Fe₂O₃) as an electrode material due to its bandgap, low cost, chemical stability and extreme abundance in nature. The α-Fe₂O₃ is also related to low carrier diffusion due to higher resistivity, slow surface kinetics, low electron mobility and higher electro-hole combination. The carrier mobility and carrier diffusion properties of α-Fe₂O₃ have been enhanced by doping as well as composite formation. Keeping in view the enhanced properties of α-Fe₂O₃, attempt is being made to dope and form composite using trivalent "aluminum" ions. The Al-α-Fe₂O₃ nanophotocatalytic materials were synthesized by varying the ratio of Al to α-Fe₂O₃ using sol-gel technique. The nanomaterials "α-Fe₂O₃ and Al-α-Fe₂O₃" were physically characterized through X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and UV-visible techniques, respectively. The diffusion coefficient of nanomaterials at the electrode/electrolyte interface was analyzed using electrochemical analysis. Interestingly, the presence of aluminum causes the α-Fe₂O₃ to change the structural, optical and morphological properties of nanomaterials. The bandgaps of α-Fe₂O₃ vary from 2.2eV to 2.45eV due to presence of aluminum in the structure. The photocurrent studied on Al-α-Fe₂O₃ based electrode clearly shows the enhanced hydrogen production under photoelectrochemical cell.