Characteristics of elemental carbon overlayers over hematite electrodes prepared by electrodeposition with organic acid additives

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.…”

“…6,14,30,38−40 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. 41,42 Another issue limiting the PEC performance of hematite is the slow kinetics of the oxygen evolution reaction (OER). Transitionmetal-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.…”

How titanium and iron are integrated into hematite to enhance the photoelectrochemical water oxidation: a review

“…Carbon materials can generally show excellent electronic conductivity with rich electrons, which could effectively promote the PEC performance of hematite. 120,121 Recently, through a hydrothermal procedure with glucose as the carbon source, a cobalt-doped carbon layer decorated Fe 2 O 3 /Fe 2 TiO 5 (C–Co–Ti–Fe 2 O 3 ) photoanode was synthesized. 122 A remarkably enhanced PEC performance including an obvious cathodic onset potential shift and a great increase in the photocurrent density was obtained (Fig.…”