In situ probe of photocarrier dynamics in water-splitting hematite (α-Fe2O3) electrodes

Huang, Zhuangqun; Lin, Yen-Yin; Xiang, Xu; Rodríguez-Córdoba, William; McDonald, Kenneth J.; Hagen, Karl S.; Choi, Kyoung‐Shin; Brunschwig, Bruce S.; Musaev, Djamaladdin G.; Hill, Craig L.; Wang, Dunwei; Lian, Tianquan

doi:10.1039/c2ee22681b

Cited by 123 publications

(180 citation statements)

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“…The fast decay dynamics observed for the TF-BaTiO 3 are typical of those observed for non-ferroelectric metal oxides, and assigned to rapid bulk recombination losses. [ 25,31,33 ] Such rapid recombination losses have been reported for numerous non-ferroelectric metal oxides with a range of crystal phases, crystallinities, and morphologies. In contrast, lifetimes on the seconds timescale comparable to the SC-BaTiO 3 have only previously reported in metal oxide systems in the presence of strong electrical bias or sacrifi cial reagents to suppress recombination of photogenerated electrons and holes.…”

Section: Doi: 101002/adma201601238mentioning

confidence: 80%

Effect of Internal Electric Fields on Charge Carrier Dynamics in a Ferroelectric Material for Solar Energy Conversion

et al. 2016

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Section: Doi: 101002/adma201601238mentioning

confidence: 80%

Effect of Internal Electric Fields on Charge Carrier Dynamics in a Ferroelectric Material for Solar Energy Conversion

et al. 2016

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“…The probe-wavelength-dependent decay kinetics has been observed in other semiconductors and is characteristic of a charge carrier trapping process. 26,27 Given that the excitation energy at 1000 nm (1.24 eV) is much lower than the band gap excitation energy (∼2.2 eV) and can only excite the plasmonic mode (step 1 in Scheme 1), it is reasonable to assign the broad absorption in the whole visible window to the photoinduced hole signal in CuS NDs. (1), a hot hole is generated through exciting the plasmonic band, which is quickly followed by the hole trapping process (2).…”

mentioning

confidence: 99%

Ultrafast Hole Trapping and Relaxation Dynamics in p-Type CuS Nanodisks

Ludwig

Pattengale

et al. 2015

J. Phys. Chem. Lett.

106

105

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CuS nanocrystals are potential materials for developing low-cost solar energy conversion devices. Understanding the underlying dynamics of photoinduced carriers in CuS nanocrystals is essential to improve their performance in these devices. In this work, we investigated the photoinduced hole dynamics in CuS nanodisks (NDs) using the combination of transient optical (OTA) and X-ray (XTA) absorption spectroscopy. OTA results show that the broad transient absorption in the visible region is attributed to the photoinduced hot and trapped holes. The hole trapping process occurs on a subpicosecond time scale, followed by carrier recombination (∼100 ps). The nature of the hole trapping sites, revealed by XTA, is characteristic of S or organic ligands on the surface of CuS NDs. These results not only suggest the possibility to control the hole dynamics by tuning the surface chemistry of CuS but also represent NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page. Letters, Vol 6, No. 14 (2015): pg. 2671-2675. DOI. This article is © American Chemical Society and permission has been granted for this version to appear in e-Publications@Marquette. American Chemical Society does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from American Chemical Society. Journal of Physical Chemistry3 the first time observation of hole dynamics in semiconductor nanocrystals using XTA.Keywords: CuS nanodisks; energy conversion; optical transient absorption spectroscopy; X-ray transient absorption spectroscopyCopper sulfides (Cu2-xS), well-known p-type semiconductors due to the stoichiometric deficiency of copper in the lattice, have attracted considerable attention because of their broad applications in diverse fields including photovoltaics, photocatalysis, batteries, chemical sensing, and electronics. [1][2][3][4] There are several stable Cu2-xS phases with the stoichiometric factor x ranging between 0 and 1, from the copperrich chalcocite (Cu2S) to the copper-deficient composition (CuS). Among them, the hexagonal covellite (CuS) is of particular interest due to its significant density of free carriers (holes) in the valence band accounting for its unique metallic conductivity and the strong localized surface plasmon resonance (LSPR) in NIR.5-8 These characteristics, together with its suitable band gap (2.2 eV), make CuS potentially ideal as low-cost light-harvesting and charge-transport materials in photovoltaics and photocatalysis. 7,[9][10][11] The successful utilization of CuS nanocrystals in photocatalysis and photovoltaic devices largely depends on the trapping and relaxation dynamics of charge carriers in CuS nanocrystals. Due to the larger amount of surface states in nanocrystals compared to the bulk materials, the electrons and holes in nanocrystals can be readily trapped at those surface states after photoexcitation, whic...

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“…[133] This additional voltage is possibly due to charge recombination at the MOx||liquid junction, whose causes have been indicated in nonideal catalysis or surface defects. [136,137] Pico to millisecond exciton recombination has been observed by transient absorption spectroscopy (TAS), [138,139] which might be relieved under anodic bias thanks to a space charge layer, [140] enabling the existence of long living holes (estimated lifetime up to 1 s under strong applied voltage) on hematite surface. Recombination phenomena sketched in Figure 16, including interfacial and surface recombinations, have been evaluated on the millisecond to second time scale.…”

Section: Role Of Recombination Processes and Oxygen Vacancies In Hemamentioning

confidence: 99%

Semiconducting Metal Oxide Nanostructures for Water Splitting and Photovoltaics

Concina

Ibupoto

Vomiero

2017

Advanced Energy Materials

117

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conduction and/or optical properties play a critical role, like in microelectronics, [17] sensing, [18,19] biosensing. [20] The possibility of exploring nanoarchi tectures for MOx (such as 0D, 1D, 2D, 3D) structures and extended networks [21,22] ) with electronic features different from their bulk counterpart [23,24] enabled their exploitation in a variety of new fields, in which networking in 3D is critical for a series of physical/chemical processes like light absorption and confinement, [25] sur face reactivity, [18,26] charge exchange/col lection. [27,28] For this reason, the possibility of extending MOx geometry from standard thin films to 3D architectures (including nanowires, nanorods, nanowalls, nano networks, and hierarchical structures), induced a renaissance for these materials, which are considered good candidates for successful application in the real life.The synthesis of composite MOx archi tectures experienced a strong and fast development in the last 15 years, now being a mature branch of Science, able to offer a diversified series of morphologies, shapes, and crystal line assemblies. [22,29] Scheme 1 illustrates the most commonly produced 0D to 2D structures (nanoparticles (NPs), nanowires (NWs), nanotubes (NTs), nanorods (NRs), nanosheets (NSs)) reported in the literature as building blocks to fabricated hier archically assembled geometries and/or nano/microarrays. In their work, [30] Umar and Hahn offer a comprehensive summary of MOx nanostructures, covering the synthesis and application, from both an experimental and theoretical point of view. Chem ical and physical preparation routes are described, including vapor transport and condensation techniques, hydrothermal and electrochemical synthesis, vacuum and nonvacuumbased techniques.While in the past focus was given on the development of new architectures and shapes through a series of physical and chemical routes, [21,22,29,31] now the research is much more focused on the investigation of the functional properties these new structures can offer, such functionalities being tailored for specific enduser applications.The research of new materials for renewable energy sources is one of the fields most benefitting of the outstanding proper ties of MOx. MOx find application in, for instance, solar cells, [32] electrochemical water splitting (WS), photoelectrochemical WS, photocatalysis. [33] In most of the cases, MOx are chosen for the possibility of having 3D networks with maximized specific sur face area, tunable bandgap allowing light absorption in a broad Metal oxide (MOx) semiconducting nanostructures hold the potential for playing a critical role in the development of a new platform for renewable energies, including energy conversion and storage through photovoltaic effect, solar fuels, and water splitting. Earth-abundant MOx nanostructures can be prepared through simple and scalable routes and integrated in operating devices, which enable exploitation of their outstanding optical, electronic, and catalytic properties. In this review, the ...

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In situ probe of photocarrier dynamics in water-splitting hematite (α-Fe2O3) electrodes

Cited by 123 publications

References 38 publications

Effect of Internal Electric Fields on Charge Carrier Dynamics in a Ferroelectric Material for Solar Energy Conversion

Effect of Internal Electric Fields on Charge Carrier Dynamics in a Ferroelectric Material for Solar Energy Conversion

Ultrafast Hole Trapping and Relaxation Dynamics in p-Type CuS Nanodisks

Semiconducting Metal Oxide Nanostructures for Water Splitting and Photovoltaics

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