Elaboration and characterization of nanoplate structured α-Fe2O3 films by Ag3PO4

Abstract

a b s t r a c tA new strategy for surface treatment of hematite nanoplates for efficient photoelectrochemical (PEC) performances is proposed. Silver orthophosphate (Ag 3 PO 4 ) has been adopted to mediate the formation of a-Fe 2 O 3 films. Phosphate ions in Ag 3 PO 4 is found to cause a significant morphology change during annealing process, from b-FeOOH nanorod arrays to hematite nanoplates. Meanwhile, Ag ions is doped into a-Fe 2 O 3 film. The obtained nanoplate structured Fe 2 O 3 -Ag-P films demonstrate much higher photoelectrochemical performance as photoanodes than the bare Fe 2 O 3 nanorod thin films. The effects of phosphate and silver ions on the morphology, surface characteristics and the PEC properties of the photoanodes are investigated.

Nanowheat-Like α-Fe2O3@Co-Based/Ti Foil Photoanode with Surface Defects for Enhanced Charge Carrier Separation and Photoelectrochemical Water Splitting

“…Hydrogen and oxygen production from photoelectrochemical (PEC) water splitting has attracted heightened interest in solar fuel application. − Hematite (α-Fe 2 O 3 ; E g = 2.2 eV) for water oxidation is stable, inexpensive, and earth-abundant. − With a 16.8% theoretical solar-to-hydrogen conversion efficiency, the PEC performance of α-Fe 2 O 3 is mainly limited by the disagreement between the long light absorption depth (118 nm light penetration depth in λ = 550 nm) and small hole diffusion length (transportation distance of carriers of <4 nm and lifetime of carriers of <10 ps). ,, Most photons absorbed by a relatively thick hematite layer are combined and do not take part in the water oxidation reaction at the PEC system. To shorten the hole-transport distance to the electrode/electrolyte interface and to enhance electrical conductivity for combating the lifetime of short carriers, many works have been studied on the formation of nanostructures − and element doping. − The developed various nanostructures − for hematite contain zero dimension (0D), ,− one dimension (1D), ,− two dimension (2D), − and three dimension (3D). ,− The one-dimensional nanostructure of α-Fe 2 O 3 is proven to be favorable for shortening the charge carrier migration distance. ,,,− There are works that focus on constructing a more favorable morphology and structure to increase the ultraviolet–visible (UV–vis) light absorption, decrease the electrochemical resistance, and reduce the recombination of the surface charge carrier. , Another issue limiting the PEC performance of hematite is the slow kinetics of the oxygen evolution reaction (OER). Transition-metal-based elements as functional catalysts for the OER in alkaline solution have been explored to improve the OER rate and reduce the overpotential, making this four-electron process with higher efficiency.…”

Phosphate‐Based Electrocatalysts for Water Splitting: Recent Progress

“…Meanwhile, considering the high cost of the noble‐metal, the co‐catalyst strategy not only reduces the dosage, but also facilitates the separation of the holes and electrons for more effective water oxidation. For example, silver phosphate decorated α‐Fe 2 O 3 nanoplates (Fe 2 O 3 −Ag 3 PO 4 ‐5) was demonstrated with comparable water oxidation performance than aforesaid single silver phosphate catalysts …”