Enhanced Light Absorption and Charge Carrier Management in Core‐Shell Fe2O3@Nickel Nanocone Photoanodes for Photoelectrochemical Water Splitting

Solar driven photoelectrochemical (PEC) water splitting is a clean and sustainable approach to generate green fuel, Hydrogen. Hematite (Fe2O3) is considered as potential photoanode because of its abundance, chemical stability and suitable band gap, though its short carrier diffusion length puts a li...

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Bibliographic Details
Published in:ChemCatChem 2019-12, Vol.11 (24), p.6355-6363
Main Authors: Singh, Ashutosh K., Sarkar, Debasish
Format: Article
Language:English
Subjects:
Arrays
Carrier lifetime
Carrier recombination
Charge transfer
Current carriers
Diffusion length
Electromagnetic absorption
Film thickness
Hematite
nanocones
Nickel
Organic chemistry
photoanode
Photoanodes
Photoelectric effect
Photoelectric emission
photoelectrochemical
Reaction kinetics
Separation
Thin films
ultrathin
Water splitting
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Summary:Solar driven photoelectrochemical (PEC) water splitting is a clean and sustainable approach to generate green fuel, Hydrogen. Hematite (Fe2O3) is considered as potential photoanode because of its abundance, chemical stability and suitable band gap, though its short carrier diffusion length puts a limit on the film thickness and subsequent light absorption capability. In this regard, here we have designed and constructed a unique photoanode by depositing ultrathin films of Fe2O3 on purpose‐built three‐dimensional (3D) nickel nanocone arrays. In this design, 3D nanostructures not only provide ameliorated surface area for PEC reactions but also enhance light absorption capability in ultrathin Fe2O3 films, while ultrathin films promote charge carrier separation and effective transfer to the electrolyte. The 3D electrodes exhibit a substantial improvement in light absorption capability within the entire visible region of solar spectrum, as well as enhanced photocurrent density as compared to the planar Fe2O3 photoelectrode. Detailed investigation of reaction kinetics suggests an optimum Fe2O3 film thickness on 3D nanocone arrays obtained after 6 deposition cycles in achieving maximum charge carrier separation and transfer efficiencies (82 % and 88 %, respectively), mainly ascribable to the increased charge carrier lifetime overcoming recombination losses. Photocatalysis: here, a novel ordered 3D Fe2O3@Nickel nanocone arrays as efficient photoanode combining the light trapping traits of ordered 3D nanostructures with the photoanodic properties of Fe2O3 is presented. Ultrathin films of Fe2O3 are deposited on 3D ordered arrays of nickel (Ni) nanocones (NCs), developed through a facile and scalable electrodeposition method, to realize the core‐shell type photoanode. The Fe2O3 coated 3D Ni NC arrays electrodes show significant enhancement in light absorption within the entire visible region of solar spectrum.
ISSN:1867-3880
1867-3899
DOI:10.1002/cctc.201901836