Reducing Graphene Oxide on a Visible-Light BiVO<sub>4</sub> Photocatalyst for an Enhanced Photoelectrochemical Water Splitting

Ng, Yun Hau; Iwase, Akihide; Kudo, Akihiko; Amal, Rose

doi:10.1021/jz100978u

Cited by 838 publications

(541 citation statements)

References 44 publications

(76 reference statements)

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“…Based on these extraordinary properties, graphene has been considered another useful material for the H 2 production because it (i) provides a support for anchoring well-dispersed metallic or oxide nanoparticles, (ii) works as a highly conductive matrix for enabling good contact throughout the matrix, (iii) induces an easy electron transfer from the conduction band of semiconductors to graphene because of the large energy level offset formed at the interface, leading to an efficient charge separation, and (iv) acts as an efficient co-catalyst for H 2 evolution due to large specific surface area and superior electron mobility [18][19][20][21][22]. However, the H 2 evolution activity of graphene as co-catalyst is still limited and needs to be further enhanced from the view point of practical applications and commercial benefits.…”

Section: Introductionmentioning

confidence: 99%

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

et al. 2014

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It is well known that the noble metal nanoparticles show active absorption in the visible region because of the existence of the unique feature known as surface plasmon resonance (SPR). Here we report the effect of plasmonic Au nanoparticles on the enhancement of the renewable hydrogen (H2) evolution through photocatalytic water splitting. The plasmonic Au/graphene/TiO2 photocatalyst was synthesized in two steps: first the graphene/TiO2 nanocomposites were developed by the hydrothermal decomposition process; then the Au was loaded by photodeposition. The plasmonic Au and the graphene as co-catalyst effectively prolong the recombination of the photogenerated charges. This plasmonic photocatalyst displayed enhanced photocatalytic H2 evolution for water splitting in the presence of methanol as a sacrificial reagent. The H2 evolution rate from the Au/graphene co-catalyst was about 9 times higher than that of a pure graphene catalyst. The optimal graphene content was found to be 1.0 wt %, giving a H2 evolution of 1.34 mmol (i.e., 26 μmolh−1), which exceeded the value of 0.56 mmol (i.e., 112 μmolh−1) observed in pure TiO2. This high photocatalytic H2 evolution activity results from the deposition of TiO2 on graphene sheets, which act as an electron acceptors to efficiently separate the photogenerated charge carriers. However, the Au loading enhanced the H2 evolution dramatically and achieved a maximum value of 12 mmol (i.e., 2.4 mmolh−1) with optimal loading of 2.0 wt% Au on graphene/TiO2 composites. The enhancement of H2 evolution in the presence of Au results from the SPR effect induced by visible light irradiation, which boosts the energy intensity of the trapped electron as well as active sites for photocatalytic activity.

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Section: Introductionmentioning

confidence: 99%

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

et al. 2014

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“…4 as a model photocatalyst. BiVO 4 , as a visiblelight-responsive photocatalyst, has attracted increasing attention in photocatalytic 15,[40][41][42] and photoelectrochemical [43][44][45] water oxidation. In addition, the BiVO 4 with large crystal size and controllable exposed facets can be easily prepared.…”

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Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4

et al. 2013

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Charge separation is crucial for increasing the activity of semiconductor-based photocatalysts, especially in water splitting reactions. Here we show, using monoclinic bismuth vanadate crystal as a model photocatalyst, that efficient charge separation can be achieved on different crystal facets, as evidenced by the reduction reaction with photogenerated electrons and oxidation reaction with photogenerated holes, which take place separately on the {010} and {110} facets under photo-irradiation. Based on this finding, the reduction and oxidation cocatalysts are selectively deposited on the {010} and {110} facets respectively, resulting in much higher activity in both photocatalytic and photoelectrocatalytic water oxidation reactions, compared with the photocatalyst with randomly distributed cocatalysts. These results show that the photogenrated electrons and holes can be separated between the different facets of semiconductor crystals. This finding may be useful in semiconductor physics and chemistry to construct highly efficient solar energy conversion systems.

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“…Development of a photoelectrode material with visible light response has been sought for efficient utilization of solar energy. It has been reported that Fe 2 O 3 (9-11), WO 3 (12)(13)(14), BiVO 4 (15)(16)(17)(18)(19)(20)(21)(22)(23)(24), and SrTiO 3 ∶Rh (25) of metal oxide electrodes respond to visible light. Recently, some (oxy) nitride materials such as TaON (26,27), Ta 3 N 5 (27,28), SrNbO 2 N (29), and Ta 0.9 Co 0.1 N x (30) have also been found to be visible light responsive photoelectrodes for water splitting.…”

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Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation

Jia

Iwashina²,

Kudo³

2012

Proc. Natl. Acad. Sci. U.S.A.

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An efficient BiVO 4 thin film electrode for overall water splitting was prepared by dipping an F-doped SnO 2 (FTO) substrate electrode in an aqueous nitric acid solution of BiðNO 3 Þ 3 and NH 4 VO 3 , and subsequently calcining it. X-ray diffraction of the BiVO 4 thin film revealed that a photocatalytically active phase of scheelite-monoclinic BiVO 4 was obtained. Scanning electron microscopy images showed that the surface of an FTO substrate was uniformly coated with the BiVO 4 film with 300-400 nm of the thickness. The BiVO 4 thin film electrode gave an excellent anodic photocurrent with 73% of an IPCE at 420 nm at 1.0 V vs. Ag∕AgCl. Modification with CoO on the BiVO 4 electrode improved the photoelectrochemical property. A photoelectrochemical cell consisting of the BiVO 4 thin film electrode with and without CoO, and a Pt counter electrode was constructed for water splitting under visible light irradiation and simulated sunlight irradiation. Photocurrent due to water splitting to form H 2 and O 2 was confirmed with applying an external bias smaller than 1.23 V that is a theoretical voltage for electrolysis of water. Water splitting without applying external bias under visible light irradiation was demonstrated using a SrTiO 3 ∶Rh photocathode and the BiVO 4 photoanode.hydrogen production | solar energy conversion | visible light response T he development of powdered photocatalysts and semiconductor photoelectrodes for water splitting have been studied extensively in view of utilization of solar energy, since the report of the Honda-Fujishima effect (1). There are advantageous and disadvantageous points for water splitting using the powdered photocatalysts and photoelectrochemical cells. Although a powdered photocatalyst system is simple, H 2 and O 2 are produced as a mixture. In contrast to it, photoelectrochemical cells give H 2 separately from O 2 gas. Moreover, even if powdered photocatalysts do not possess band potentials suitable for water splitting (the bottom of the conduction band <0 V and the top of the valence band >1.23 V vs. NHE at pH 0), water splitting may be achieved by application of these powdered photocatalysts to photoelectrodes with applying some external bias. However, the electrical conductivity of semiconductor electrode is indispensable, resulting in that the number of the photoelectrode materials is limited.It has been reported that many metal oxides are active photocatalysts for water splitting into H 2 and O 2 stoichiometrically under UV light irradiation (2). Photoelectrodes, such as TiO 2 (1, 3, 4), SrTiO 3 (5, 6), BaTiO 3 (7), and KTaO 3 (8) have been reported for photoelectrochemical water splitting under UV light irradiation. Development of a photoelectrode material with visible light response has been sought for efficient utilization of solar energy. It has been reported that Fe 2 O 3 (9-11), WO 3 (12-14), BiVO 4 (15-24), and SrTiO 3 ∶Rh (25) of metal oxide electrodes respond to visible light. Recently, some (oxy) nitride materials such as TaON (26,27), Ta 3 N 5 (27, 28), SrN...

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Reducing Graphene Oxide on a Visible-Light BiVO₄ Photocatalyst for an Enhanced Photoelectrochemical Water Splitting

Cited by 838 publications

References 44 publications

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4

Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation

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Reducing Graphene Oxide on a Visible-Light BiVO4 Photocatalyst for an Enhanced Photoelectrochemical Water Splitting

Cited by 838 publications

References 44 publications

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

Graphene supported plasmonic photocatalyst for hydrogen evolution in photocatalytic water splitting

Spatial separation of photogenerated electrons and holes among {010} and {110} crystal facets of BiVO4

Facile fabrication of an efficient BiVO 4 thin film electrode for water splitting under visible light irradiation

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Reducing Graphene Oxide on a Visible-Light BiVO₄ Photocatalyst for an Enhanced Photoelectrochemical Water Splitting

Facile fabrication of an efficient BiVO ₄ thin film electrode for water splitting under visible light irradiation