Ultra-efficient and durable photoelectrochemical water oxidation using elaborately designed hematite nanorod arrays

Jeon, Tae Hwa; Moon, Gun‐hee; Park, Hyunwoong; Choi, Wonyong

doi:10.1016/j.nanoen.2017.06.049

Cited by 192 publications

(135 citation statements)

References 42 publications

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“…Cobalt‐phosphate (Co‐Pi), one of the most studied co‐catalysts for α‐Fe 2 O 3 photoanodes, has been used to greatly enhance the anodic photocurrent while yielding large cathodic shift of the onset potential. This effect induces an accelerated water oxidation reaction, thereby promoting PEC water splitting …”

Section: Introductionmentioning

confidence: 99%

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Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

et al. 2018

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Functional nanoscale interfaces that promote the transport of photoexcited charge carriers are fundamental to efficient hydrogen production during photoelectrochemical (PEC) splitting of water. Here, the realization of a functional one‐dimensional nanostructure achieved through surface engineering of hematite (α‐Fe2O3) nanorods with a TiO2 overlayer is reported. The surface‐engineered hematite nanostructure exhibits significantly improved PEC performance as compared to untreated α‐Fe2O3, with an increase in the maximum incident photon‐to‐current efficiency (IPCE) of nearly 400% at 350 nm. While addition of the TiO2 overlayer did not alter the lifetime of photoexcited charge carriers, as evidenced from transient absorption spectroscopy, it is found that the presence of TiO2 could enhance oxygen electrocatalysis by interfacial electron enrichment, largely attributed to enhanced O(2p)−Fe(3d) hybridization. Moreover, the interfacial electronic structure revealed from XANES measurements of the α‐Fe2O3/TiO2 nanorods suggests that photoexcited holes in α‐Fe2O3 may efficiently transfer through the TiO2 overlayer to the electrolyte while electrons migrate to the external circuit along the one‐dimensional nanorods, thereby promoting charge separation and enhancing PEC splitting of water.

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Section: Introductionmentioning

confidence: 99%

“…As a result, transitions to and from the associated electronic states of engineered transition metal oxide‐based hetero‐nanostructures could be potentially utilized for PEC‐based solar fuel generation. Consequently, a variety of α‐Fe 2 O 3 /TiO 2 hetero‐nanostructures have shown considerable improvement in PEC water splitting …”

Section: Introductionmentioning

confidence: 99%

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

et al. 2018

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“…In a sharp contrast, with TiO 2 overlayer coated, the η sep is greatly enhanced for the α‐Fe 2 O 3 /Co(dca) 2 /TiO 2 photoanode. This could be explained by the surface passivation effect of the TiO 2 overlayer, which could promote the photogenerated holes transfer to the photoanode/electrolyte interface by inhibiting the electron and hole recombination . Such increase in η sep induced by the TiO 2 overlayer could also be evidenced in the case of the α‐Fe 2 O 3 /TiO 2 photoanode with only TiO 2 coated as the passivation layer (Figure S8a).…”

Section: Resultsmentioning

confidence: 90%

Protected Hematite Nanorod Arrays with Molecular Complex Co‐Catalyst for Efficient and Stable Photoelectrochemical Water Oxidation

Chen

Kong

et al. 2018

Eur J Inorg Chem

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Herein, a hybrid structure of hematite (α‐Fe2O3) nanorod arrays is designed, with surface catalyzed by Co molecular complex (Co(dca)2, dca: dicyanamide) and then protected by TiO2 thin overlayer, for efficient and stable photoelectrochemical (PEC) water oxidation. The obtained α‐Fe2O3/Co(dca)2/TiO2 hybrid nanorod arrays show much improved and stabilized PEC performance as compared to the pristine, and even the Co(dca)2 or TiO2 modified α‐Fe2O3, with a photocurrent density of 0.35 mA cm–2 obtained at 1.23 V vs. reversible hydrogen electrode (RHE), and an incident photon‐to‐current conversion efficiency (IPCE) reaching 16 % at 400 nm at 1.6 V vs. RHE. It has been demonstrated that the adsorbed Co(dca)2 molecular complex could effectively promote the interface charge transfer process and accelerate the water oxidation reaction kinetics, meanwhile the atomic layer deposited TiO2 overlayer could passivate the surface defects of α‐Fe2O3 and suppress the surface charge carrier recombination. Moreover, the TiO2 overlayer could effectively protect Co(dca)2 from detaching from the α‐Fe2O3 surface and thus stabilize the PEC activity for water oxidation reaction. The present study provides some available thoughts and methods for rational design of highly efficient photoelectrodes for water splitting from the perspective of the surface and interface engineered charge carrier transfer and water oxidation processes.

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“…Such hematite nanostructures achieving up to 6 mA cm −2 at 1.23 V versus RHE were demonstrated having feature thicknesses of up to 730 nm. [55,56] Our optical model will be highly useful in the process of designing this hematite nanostructure and represents a powerful tool for the optimization of the optical performance of PEC cells based on one or multielectrode (tandem) designs employing various materials. Moreover, it represents a cornerstone of a complete (optical and electrical) model for PEC water splitting cells that is currently under way to be developed.…”

Section: Discussionmentioning

confidence: 99%

Analysis of Optical Losses in a Photoelectrochemical Cell: A Tool for Precise Absorptance Estimation

Cendula

Steier

Losio

et al. 2017

Adv Funct Materials

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Optical losses in a photoelectrochemical (PEC) cell account for a substantial part of solar-to-hydrogen conversion losses, but limited attention is paid to the detailed investigation of optical losses in PEC cells. In this work, an optical model of combined coherent and incoherent light propagation in all layers of the PEC cell based on spectroscopic measurements is presented. Specifically, photoelectrodes using transparent conductive substrates such as F:SnO 2 coated with thin absorber films are focused. The optical model is verified for hematite photoanodes fabricated by atomic layer deposition and successfully used to determine wavelength-dependent reflection, transmission, layer absorptances, and charge generation rates. Furthermore, the calculated absorptances enable 20-30% more accurate calculations of the absorbed photon-to-current efficiency of PEC cells. Our optical model is a powerful tool for the optimization of the optical performance of PEC cells focusing on single absorber or tandem configurations and represents a cornerstone of a complete (optical and electrical) model for PEC water splitting cells.

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Ultra-efficient and durable photoelectrochemical water oxidation using elaborately designed hematite nanorod arrays

Cited by 192 publications

References 42 publications

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

Protected Hematite Nanorod Arrays with Molecular Complex Co‐Catalyst for Efficient and Stable Photoelectrochemical Water Oxidation

Analysis of Optical Losses in a Photoelectrochemical Cell: A Tool for Precise Absorptance Estimation

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