Yttrium-doped hematite photoanodes for solar water splitting: Photoelectrochemical and electronic properties

We investigate yttrium-doped hematite thin-film photoelectrochemical properties and find yttrium incorporation to amply improve the performance as a photoanode for water splitting under visible light. We used the spray pyrolysis method to prepare a set of yttrium doped Fe_2-xY_xO₃ (x = 0, 0.05, 0.10, 0.15, 0.2) thin films (thickness below 500 nm) on glass and transparent conductive oxide coated glass slides. Using a substitutional homovalent (Y³⁺) dopant, the effect on functionality is rationalised as a combined effect on the electronic structure and small polaron mobility from the lattice structure, impurity levels, lattice stability and variance in hybridisation. The photoelectrochemical response measurements indicate highest performance at Fe_1.9Y_0.1O₃ composition.