Visible-light photocatalytic properties and electronic structure of Zr-based oxynitride, Zr2ON2, derived from nitridation of ZrO2

Mishima, Takahiro; Matsuda, Motohide; Miyake, Michihiro

doi:10.1016/j.apcata.2007.03.017

Cited by 63 publications

(38 citation statements)

References 23 publications

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“…Water splitting using semiconductor photocatalysts is a potential technique to create completely clean hydrogen from water using sunlight as the light source [1]. Recently, (oxy)nitrides containing transition metal ions of Ti 4 þ , Zr 4 þ , Nb 5 þ , or Ta 5 þ with d 0 electronic configuration and (oxy)nitrides containing typical metal ions of Ga 3 þ , In 3 þ , or Ge 4 þ with d 10 electronic configuration have been reported as visible light-driven photocatalysts having potential for water splitting [2][3][4]. However, (oxy)nitrides containing d 0 metal ion have not achieved overall water splitting.…”

Section: Introductionmentioning

confidence: 99%

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Kishida¹,

Watanabe²

2012

Journal of Solid State Chemistry

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Section: Introductionmentioning

confidence: 99%

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Kishida¹,

Watanabe²

2012

Journal of Solid State Chemistry

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“…27 In addition, N insertion into the ZrO2 lattice modifies the electronic structure of the oxide. 28 The oxynitride phase can also constitute an intrinsic source of highly active sites for the adsorbtion and activation of water, thanks to the presence of cerium as dopant. Moreover, since nature of the segregated phases and surface characteristics of the material significantly influence the H2 yield, 29 a synergy between the ceria-rich phase and the oxynitride structure in promoting the adsorption and splitting of water is conceivable.…”

mentioning

confidence: 99%

Water splitting reaction on Ce_0.15Zr_0.85O₂ driven by surface heterogeneity

Pappacena

Boaro

Armelao

et al. 2016

Catal. Sci. Technol.

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The compositional and structural heterogeneity of a sample of Ce0.15Zr0.85O2 subjected to a two-step thermochemical water splitting reaction was investigated by means of X-ray powder diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS) and High-Resolution Transmission Electron Microscopy (HRTEM) analysis. High temperature treatment under N2 resulted in segregation of a Zr-rich monoclinic phase on one side and a Ce-rich cubic phase on the other. The treatment also led to a higher reducibility of the material compared to similar studies on Ce-rich compositions. HRTEM revealed the presence of a zirconia based superstructure that it is identifiable with an oxynitride phase Zr2ON2, while ceria surface enrichment was detected via XPS. H2 yield, investigated at 800°C by pulsing water over several redox cycles, showed a six-fold increase after the first cycle remaining constant after at least three subsequent cycles. The presence of zirconia oxynitride was found to be beneficial for both the oxidation and reduction steps. Solar thermochemical water splitting cycles (WSC) are an attractive carbon-free approach to H2 production from water and sunlight.1 Two-step metal oxide based cycles generate H2 through high temperature (~1500-2000°C) reduction in inert atmosphere and the subsequent water oxidation at a lower (~400-1300°C) temperature making water splitting (WS) possible at temperatures lower than the thermodynamic value (2300°C). 2 Among many metal oxides investigated in literature, ceria is one of the most viable candidates, 3 and it can deliver pure oxygen and hydrogen according to the following two-step redox cycleThe main drawback of this cycle is that a significant reduction of ceria occurs only at temperatures higher than 1800°C, where sublimation can occur with a decrease of the yield over cycles. 5 It follows that studies on ceria-based systems have been focused on lowering the reduction temperature of the Ce 4+ /Ce 3+ redox couple, while maintaining the high reactivity of reduced Ce 3+ species towards water. 3,6 The addition of high valence dopant cations, such as Zr 4+ , proved effective in increasing the thermodynamic driving force of CeO2 reduction at lower temperatures, 7-9 and the effect of zirconium content in the two step water splitting reaction has been widely studied. [10][11][12][13][14] Its presence favours CeO2 reduction under inert atmosphere at temperatures lower than 1500°C preventing sublimation and the consequent yield loss; moreover, the increased oxygen storage of ceria-zirconia positively affects O2yield. On the other hand, the H2 productivity depends on the number of exposed surface redox sites, and thus on the textural, morphological and structural properties of these materials. It was reported that in these materials the kinetics of water splitting is often hampered by gassolid diffusion limitations due to the simultaneous occurence of sintering processes. Several efforts have been made to overcome this issue, and the change of the morphological and structural properties o...

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“…Moreover, the Ta_5d and/or Zr_4d orbitals played an important role in the conduction band and showed little contribution to the valence band near the gap. Finally, isolated states which may act as a recombination center for photogenerated carriers [40], were not observed in the band gap, in consistence with the UVeVis shapes of Fig. 3. …”

Section: Electronic Propertiesmentioning

confidence: 68%

CaTaO2N–CaZrO3 solid solution: Band-structure engineering and visible-light-driven photocatalytic hydrogen production

Shi

Zhou

et al. 2012

International Journal of Hydrogen Energy

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Visible-light photocatalytic properties and electronic structure of Zr-based oxynitride, Zr2ON2, derived from nitridation of ZrO2

Cited by 63 publications

References 23 publications

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Water splitting reaction on Ce_0.15Zr_0.85O₂ driven by surface heterogeneity

CaTaO2N–CaZrO3 solid solution: Band-structure engineering and visible-light-driven photocatalytic hydrogen production

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Visible-light photocatalytic properties and electronic structure of Zr-based oxynitride, Zr2ON2, derived from nitridation of ZrO2

Cited by 63 publications

References 23 publications

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Improvement of photocatalytic activity of tantalum nitride by ammonothermal treatment at high pressure

Water splitting reaction on Ce0.15Zr0.85O2 driven by surface heterogeneity

CaTaO2N–CaZrO3 solid solution: Band-structure engineering and visible-light-driven photocatalytic hydrogen production

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Water splitting reaction on Ce_0.15Zr_0.85O₂ driven by surface heterogeneity