Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

Shen, Shaohua; Kronawitter, Coleman X.; Wheeler, Damon A.; Guo, Peijun; Lindley, Sarah A.; Jiang, Jiangang; Zhang, Jin Z.; Guo, Liejin; Mao, Samuel S.

doi:10.1039/c3ta13453a

Cited by 85 publications

(91 citation statements)

References 66 publications

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“…As shown in Figure S1, Supporting Information, these films display similar Raman spectra, with all peaks assigned to hematite . The small peak around 660 cm −1 for the α‐Fe 2 O 3 /TiO 2 nanorod films can be attributed to surface disorders resulting from surface passivation of α‐Fe 2 O 3 with TiO 2 . In previous studies, surface passivation was proposed as an effective method to enhance the PEC performance of α‐Fe 2 O 3 photoanodes .…”

Section: Resultsmentioning

confidence: 76%

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: Resultsmentioning

confidence: 76%

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

et al. 2018

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“…Elemental doping plays a critical role in improving the electrical conductivity and in enhancing the PEC performance of hematite photoanodes [5,15]. Dopants, such as Si [16,17], Ti [17][18][19][20][21], Sn [6,15,17,22], Zr [18], Ge [17,23], Mn [14,17], Al [24], and Pt [9,12,25], have been investigated for use in hematite photoanodes. Sn has an advantage over other dopants because Sn ions have a similar ionic radius and Pauling electronegativity compared to Fe ions.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of superior α-Fe2O3 nanorod photoanodes through ex-situ Sn-doping for solar water splitting

Annamalai

Shinde

Jeon

et al. 2016

Solar Energy Materials and Solar Cells

113

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“…To further improve the photoactivity of hematite photoanode, element doping has been extensively studied to improve the structural, electronic and optical properties of hematite. The role of dopants, such as Ti, Si, Al, Mg, Zn, Be, Mo, and Sn, on the PEC performance of hematite have been investigated. Recently, there is an increasing interest of developing Sn‐doped hematite nanostructured photoanode due to the significant effect of Sn doping on the photoactivity of hematite.…”

Section: Introductionmentioning

confidence: 99%

Review of Sn‐Doped Hematite Nanostructures for Photoelectrochemical Water Splitting

Ling

2014

Part & Part Syst Charact

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Hematite (α-Fe 2 O 3 ) nanostructures have been extensively studied as photoanodes for photoelectrochemical (PEC) water splitting. However, the photoactivity of pristine hematite nanostructures is limited by a number of factors, including poor electrical conductiviy and slow oxygen evolution reaction kinetics. Previous studies have shown that using tin (Sn) as an n-type dopant can substantially enhance the photoactivity of hematite photoanodes by modifying their optical and electrical properties. Here, the recent accomplishments in using Sn-doped hematite photoanodes for solar water splitting are highlighted.1.9-2.2 eV [ 59 ] for harvesting solar light, which corresponding to a high theoretical STH conversion effi ciency of 14%-17%. [ 60 ] Iron is the fourth most abundant element in the Earth's crust (6.3% by weight), [ 5 ] and hematite is a low-cost material. In addition, hematite is chemically stable in solutions of different pH. [ 61 ] However, the STH conversion effi ciencies of reported hematite photoanodes are considerably lower than the theoretical value, owing to its very short-excited state lifetime (<10 ps), [ 62 ] short hole diffusion length (≈2-4 nm), [ 5,61 ] poor surface oxygen evolution reaction kinetics, [ 63 ] and poor electrical conductivity (10 −6 Ω −1 cm −1 ). [ 5 ] The recent development of hematite nanostructures, including nanoparticles, [ 59,64,65 ] nanowires [ 66,67 ] and nanonets, [ 56,58 ] opens up new opportunities in addressing the abovementioned limitations. Nanostructured photoanode offers increased semiconductor/electrolyte interfacial area for water oxidation, as well as substantially reduced diffusion length for minority carriers. Therefore, nanostructured hematite photoelectrodes are expected to be more effi cient in charge carrier collection than their bulk counterparts. [ 60 ] For example, Lin et al. reported the growth of ultrathin hematite fi lm (25 nm) on a conductive nanonet structure. The nanonet-based hematite photoanode achieved an excellent photocurrent of 1.6 mA cm −2 at 1.23 V versus RHE, which is four times higher than the value obtained from the planar sample with the same thickness. The photocurrent enhancement was due to the increased activation sites for water oxidation ( Figure 2 ). [ 56 ] To further improve the photoactivity of hematite photoanode, element doping has been extensively studied to improve the structural, electronic and optical properties of hematite. The role of dopants, such as Ti, [ 65,[68][69][70][71][72][73][74][75] Si, [ 68,[76][77][78][79] Al, [ 71,80 ] Mg, [ 81,82 ] Zn, [ 71,78 ] Be, [ 80 ] Mo, [ 83 ] and Sn, [ 4,61,69,80,81,[84][85][86][87][88][89][90] on the PEC performance of hematite have been investigated. Recently, there is an increasing interest of developing Sn-doped hematite nanostructured photoanode due to the signifi cant effect of Sn doping on the photoactivity of hematite. Sn 4+ is a tetravalent dopant that can be substitutionally doped into hematite at the Fe 3+ sites. [ 69,71,89 ] The electrical conductivity of Sn-doped hema...

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Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth

Cited by 85 publications

References 66 publications

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

Enhancing Solar‐Driven Water Splitting with Surface‐Engineered Nanostructures

Fabrication of superior α-Fe2O3 nanorod photoanodes through ex-situ Sn-doping for solar water splitting

Review of Sn‐Doped Hematite Nanostructures for Photoelectrochemical Water Splitting

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