Optimization for visible light photocatalytic water splitting: gold-coated and surface-textured TiO2 inverse opal nano-networks

Kim, Kwang-Hyun; Thiyagarajan, Pradheep; Ahn, Hyo-Jin; Kim, Sun‐I; Jang, Ji‐Hyun

doi:10.1039/c3nr01552a

Cited by 67 publications

(65 citation statements)

References 60 publications

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“…However, TiO 2 can only absorb ultraviolet light which is only 3-5 % of solar light due to its wide band gap of 3.2 eV [4][5][6]. As a consequence, various approaches have been developed for improving the visible light photocatalytic efficiency, including metal and/or non-metal ion doping, surface chelation, and mixing of two semiconductors [7][8][9]. On the other hand, many researchers have diverted their attention to develop novel photocatalytic materials with high activity [10,11].…”

Section: Introductionmentioning

confidence: 99%

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

et al. 2015

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Highly crystalline MgSn(OH) 6 cubic and polyhedral nanoparticles were synthesized via hydrothermal method by adjusting the ethanol/water ratio. Mg 2 SnO 4 / SnO 2 nanoparticles have been successfully obtained by subsequent calcining, which maintain the original morphologies of the precursor with shrank size and rough surface. The structural properties of Mg 2 SnO 4 /SnO 2 heterostructures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy, and N 2 adsorption/desorption isotherms. The photocatalytic activity of the Mg 2 SnO 4 / SnO 2 nanoparticles was further evaluated by the degradation of methylene blue (MB) under UV illumination. The obtained results revealed that Mg 2 SnO 4 /SnO 2 polyhedral nanoparticles have excellent performance on photocatalytic degradation of MB. It is assumed that the red shift of band gap, oxygen vacancies, and higher specific surface areas of polyhedral Mg 2 SnO 4 /SnO 2 nanocomposites contribute to the enhancement in the photocatalytic activity.

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Section: Introductionmentioning

confidence: 99%

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

et al. 2015

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“…[1][2][3][4][5][6] Since Fujishima and Honda rst reported a PEC water splitting system using a titanium dioxide semiconductor, n-type semiconductors have been considered to be promising photoanode materials for PEC water splitting cells. 7,8 Hematite (a-Fe 2 O 3 ) is a very attractive material among n-type semiconductors for PEC water splitting because of its relatively narrow band gap (2.1-2.2 eV) and superior chemical stability in electrolytes.…”

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confidence: 99%

Nanoporous hematite structures to overcome short diffusion lengths in water splitting

et al. 2014

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In this report, we show that by creating a nanoporous haematite (aFe 2 O 3 ) structure using boric acid (H 3 BO 3 ) treatment, the chronic issue of the short diffusion length of carriers in a-Fe 2 O 3 for photo- Photoelectrochemical (PEC) water splitting cells which use solar energy to produce hydrogen or oxygen gas are a promising technology for solving the energy crisis and environmental problems. 1-6 Since Fujishima and Honda rst reported a PEC water splitting system using a titanium dioxide semiconductor, n-type semiconductors have been considered to be promising photoanode materials for PEC water splitting cells.7,8 Hematite (a-Fe 2 O 3 ) is a very attractive material among n-type semiconductors for PEC water splitting because of its relatively narrow band gap (2.1-2.2 eV) and superior chemical stability in electrolytes.9,10 More importantly, compared to rare semiconductor materials (As, Ga, In, Se, and so on), which are commonly used in monolithic photovoltaic-PEC cells, a-Fe 2 O 3 is very cheap and abundant, and therefore, able to achieve high solar-to-hydrogen (STH) efficiency economically. The elemental doping of a-Fe 2 O 3 uses a relatively simple procedure and has attracted much attention as a way to improve a-Fe 2 O 3 performance by increasing its electronic conductivity and carrier life time. 16,[20][21][22] However, the use of rare metal dopants such as Pt, Si, and Ti and so on increases the overall price of the PEC cell. Alternatively, it has been reported that forming oxygen vacancies in semiconductors such as TiO 2 and a-Fe 2 O 3 by treatment with reducing agents could enhance the PEC performance by increasing the donor density. In particular, Fe 2+ ions in a-Fe 2 O 3 with oxygen vacancies could dramatically increase the conductivity of the a-Fe 2 O 3 via a polaron hopping mechanism. 23Controlling the nanostructure morphology of a-Fe 2 O 3 has been another efficient way to overcome the disadvantages of aFe 2 O 3 by increasing its surface area and reducing the path length of hole transport. For example, diverse morphologies of a-Fe 2 O 3 such as mesoporous nanotubes/nanowires and threedimensional nano-structures have exhibited much improved PEC performance compared to normal lm type a-Fe 2 O 3 . 24-26Although the control of a-Fe 2 O 3 morphology has produced highly enhanced performance, the fabrication process involves complex steps and the resulting particle sizes are above 50-80 nm which are still signicantly larger than the 2-4 nm hole diffusion length. 10,27 In this work, the fabrication of boric acid (H 3 BO 3 ) treated a-Fe 2 O 3 with optimized sizes using a cheap and broadly applicable hydrothermal growth method is reported. The dissociation constant of the [FeB(OH) 4 ] 2+ complex controls the rate of formation of b-FeOOH, and accounts for the nal nanoporous morphology of a-Fe 2 O 3 nanorods with $15 nm

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“…Prominently, a 5-fold enhancement in photocurrent density was achieved by S-IO-TiO 2 in comparison to that of M-IO-(B), markedly higher than those reported elsewhere. 14,[53][54][55][56][57] The calculated photonto-electron conversion efficiency (IPCE) at the wavelength (380 nm) of the S-IO-TiO 2 photoanodes reached a value of 53%, significantly higher than that of H-IO-TiO 2 , M-IO-(B) and ncTiO 2 (15%, 10%, and 1%, respectively). Such an extraordinary performance of S-IO-TiO 2 demonstrates that the light utilization at 380 nm has been enhanced by more than 5 fold, in comparison to M-IO-B.…”

Section: Resultsmentioning

confidence: 99%

Sandwich-structured TiO₂ inverse opal circulates slow photons for tremendous improvement in solar energy conversion efficiency

et al. 2017

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To cite this version:Photon management has enabled a true revolution in the development of high-performance semiconductor materials and devices. Harnessing the highest amount of energy from photon relies on an ability to design and fashion structures to trap the light for the longer time inside the device for more electron excitation. The light harvesting efficiency in many thin-film optoelectronic devices is limited due to low photon absorbance. Here we demonstrate for the first time that slow photon circulation in sandwich-structured photonic crystals with two stopbands fine tuned are ideally suited to enhance and spectrally engineer light absorption. The sandwich-structured TiO 2 inverse opal possesses two stopbands, whose blue or red edge is respectively tuned to overlap with TiO 2 electronic excitation energy, thereby circulating the slow photons in the middle layer and enhancing light scattering at layer interfaces. This concept, together with the significantly increased control over photon management opens up tremendous opportunities for the realization of a wide range of highperformance, optoelectronic devices, and photochemical reactions.

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Optimization for visible light photocatalytic water splitting: gold-coated and surface-textured TiO2 inverse opal nano-networks

Cited by 67 publications

References 60 publications

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

Nanoporous hematite structures to overcome short diffusion lengths in water splitting

Sandwich-structured TiO₂ inverse opal circulates slow photons for tremendous improvement in solar energy conversion efficiency

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Optimization for visible light photocatalytic water splitting: gold-coated and surface-textured TiO2 inverse opal nano-networks

Cited by 67 publications

References 60 publications

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

Facile synthesis and photocatalytic performance of Mg2SnO4/SnO2 heterostructures

Nanoporous hematite structures to overcome short diffusion lengths in water splitting

Sandwich-structured TiO2 inverse opal circulates slow photons for tremendous improvement in solar energy conversion efficiency

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Product

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Sandwich-structured TiO₂ inverse opal circulates slow photons for tremendous improvement in solar energy conversion efficiency