How Should Iron and Titanium be Combined in Oxides to Improve Photoelectrochemical Properties?

Abstract

We discuss here for the first time how to combine iron and titanium metal ions to achieve a high photo-electrochemical activity for TiO 2 -based photo-anodes in water splitting devices. To do so, a wide range of photoelectrode materials with tailored Ti/Fe ratio and element vicinity were synthesized by using the versatility of aqueous sol-gel chemistry in combination with a microwave-assisted crystallization process. At low ferric concentrations, single phase TiO 2 anatase doped with various Fe amounts were prepared. Strikingly, at higher ferric concentrations, propose that the nature of the heterojunction impacts charge carrier recombination. The results presented herein not only answer whether iron and titanium should be combined in the same structure or into heterostructured systems, but also on the importance of the arrangement of ions in the structure to improve the performances of the photoanode.

Photocatalytic degradation of methylene blue under natural sunlight using iron titanate nanoparticles prepared by a modified sol–gel method

“…The determined unit cell parameters and atomic positions are given in table 1. Refinement of ion occupancy showed that differing from the previously obtained fully disordered structure [19] iron ions showed a slight preference for 4c sites occupying royalsocietypublishing.org/journal/rsos R. Soc. Open Sci.…”

Structure and optical properties of sputter deposited pseudobrookite Fe2TiO5 thin films

“…The conventional cell of Fe 2 TiO 5 (orthorhombic structure, space group #63), which contains 32 atoms, was relaxed using the Monkhorst-Pack scheme 21 with a 9 × 3 × 3 k-points grid until the force on each atom was less than 0.005 eV Å −1 . Because the exact state of the FeIJIII) atoms is not clear, 6 we performed all calculations with the most stable spin state: antiferromagnetic configuration. The calculated band gaps with conventional DFT are underestimated compared to the experimental ones.…”

“…In comparison with α-Fe 2 O 3 and anatase TiO 2 , Fe 2 TiO 5 exhibits intermediate behavior with desirable optical band gap compared to α-Fe 2 O 3 and electronic transport compared to anatase TiO 2 . 6 Among various investigated materials, Fe 2 TiO 5 is expected to be an excellent substitute for TiO 2 in many potential applications, including water oxidation, 1 photo-degradation, 2 ceramic pigments, 3 proton exchange membranes, 4,7 Li-ion battery anodes 8,9 and gas sensors. 10 It consists of earth-abundant elements (obtainable from ilmenite mineral), 11 exhibits high chemical surface stability, and a relatively small band gap (2.1 eV).…”

Síntese E Caracterização De Heterojunções De Titanatos De Fe E Cu Crescidos Sobre Tio2 Para Fotólise Da Água

“…Por fim, para que seja possível a transferência dos portadores de carga para as espécies reacionais faz-se necessário que as bandas de valência (VB) e de condução (CB) do material apresentem posicionamentos compatíveis com os potenciais de oxi-redução das reações de interesse. A eficiência da etapa de transferência dos portadores, entretanto, não é determinada apenas pelas propriedades da estrutura do material, mas também pela estrutura eletrônica da interface com o meio [6].…”

“…Apesar das excelentes propriedades particularmente interessantes para o seu uso para fotocatálise, o TiO 2 ainda mantém duas grandes limitações que comprometem a sua aplicação: (1) elevada energia de band-gap; e (2) alta taxa de recombinação dos portadores de carga [6]. Nesse sentido, diferentes estratégias têm sido adotatadas para aprimorar a eficiência de fotoabsorção do material mantendo sua boa combinação de propriedades catalíticas.…”