Iron based photoanodes for solar fuel production

Abstract

In natural photosynthesis, the water splitting reaction of photosystem II is the source of the electrons/reducing equivalents for the reduction of carbon dioxide to carbohydrate while oxygen is formed as the by-product. Similarly, for artificial photosynthesis where the end product is a solar fuel such as hydrogen, a water splitting-oxygen evolving system is required to supply high energy electrons to drive the reductive reactions. Very attractive candidates for this purpose are iron based semiconductors which have band gaps corresponding to visible light and valence band energies sufficient to oxidise water. The most studied system is hematite (Fe2O3) which is highly abundant with many attributes for incorporation into photoelectrochemical (PEC) cells. We review the recent progress in manipulating hematite for this purpose through nanostructuring, doping and surface modifications. We also consider several hybrid iron-based semiconducting systems like ferrites and iron titanates as alternatives to hematite for light driven water splitting emphasizing their advantages with respect to their band levels and charge transport properties.

Ir-phosphate cocatalyst for photoelectrochemical water oxidation using α-Fe2O3

“…The absorption edge is around 567 nm which is close to the values reported in the literature. [4][5][6] However, aer depositing Ir-Pi on the surface of a-Fe 2 O 3 , the absorption onset is blue shied to 545 nm (Fig. 6a(ii)), indicating a modied band gap.…”

“…Despite having favorable light absorbing features and valence band position, the reported efficiencies of photoelectrochemical (PEC) water oxidation at a-Fe 2 O 3 electrodes are extremely low. [4][5][6] The poor efficiency has been attributed to a low rate constant of water oxidation reaction (WOR) by photogenerated holes, and short hole diffusion length (2-4 nm) which allows only holes close to the surface to participate in the reaction. 7 Issues related with short hole diffusion lengths have been largely addressed by nanostructuring of the photoelectrodes.…”

“…Furthermore, it is attractive owing to high abundance, low cost, non-toxicity, good stability, and environmental compatibility. 4,5 On the other hand, its conduction band is not negative to water reduction potential and hence external bias is needed to drive hydrogen evolution reaction at the cathode. The required bias voltage can be provided by a solar cell connected in a tandem conguration.…”

Synthesis and characterization of black, red and yellow nanoparticles pigments from the iron sand

“…The crystal structure of hematite is trigonal with space group R-3c with lattice parameters a = 5.0356 Å and c= 13.7489 Å [12]. Hematite nanoparticles have several applications such as pigments for paints, drug targeting cancer cells and for labeling and tracking target cells using magnetic resonance imaging (MRI) [13][14].…”

A New Insight in the Physical and Photoelectrochemical Properties of Molybdenum Disulfide Alpha-Hematite Nanocomposite Films

“…Iron oxide, bismuth vanadate, tungsten oxide, and tantalum nitride are the examples of low band gap semiconducting materials [5]. The α-Fe 2 O 3 is one of the most attractive photo-anode materials with efficiency of 16% to convert solar-to-hydrogen [5] [7]- [14]. The α-Fe 2 O 3 has been applied for photoelectrochemical applications due to low bandgap (2.1 -2.2 eV), low cost, high chemical stability, nontoxicity, and abundance in nature [5].…”