Enhanced light harvesting and charge separation over wormhole mesoporous TiO<sub>2−X</sub> nanocrystallites towards efficient hydrogen generation

Negi, Sanjay Singh

doi:10.1039/c8se00580j

Cited by 12 publications

(6 citation statements)

References 57 publications

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“…The 2.8F-La/TiO 2 photocatalyst showed both the highest photocatalytic activity and the photocurrent response as well. This is in agreement with many other authors [19,41,42,43].…”

Section: Resultssupporting

confidence: 94%

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

et al. 2019

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F-La/TiO2 photocatalysts were studied in photocatalytic decomposition water-methanol solution. The structural, textural, optical, and electronic properties of F-La/TiO2 photocatalysts were studied by combination of X-ray powder diffraction (XRD), nitrogen physisorption, Ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS), Electrochemical impedance spectroscopy (EIS), and X-ray fluorescence (XPS). The production of hydrogen in the presence of 2.8F-La/TiO2 was nearly up to 3 times higher than in the presence of pure TiO2. The photocatalytic performance of F-La/TiO2 increased with increasing photocurrent response and conductivity originating from the higher amount of fluorine presented in the lattice of TiO2.

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“…The 2.8F-La/TiO 2 photocatalyst showed both the highest photocatalytic activity and the photocurrent response as well. This is in agreement with many other authors [19,41,42,43].…”

Section: Resultssupporting

confidence: 94%

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

et al. 2019

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“…Lattice fringes were observed in the HRTEM images, corresponding to the CeO 2 (111) ( d = 0.31 nm) facets of cubic fluorite, along with the Co 3 O 4 (311) ( d = 0.24 nm) faceted planes. A pseudo three-dimensional (3d) structure was observed, which provided a low diffusional barrier owing to the shallow pore depths . The HRTEM data are in good agreement with the N 2 physisorption results, confirming that the Co/Nb-CeO 2 materials have high surface areas, leading to a high interface density, which is beneficial for tandem catalytic processes.…”

Section: Resultssupporting

confidence: 70%

Restructuring Co–CoO_x Interface with Titration Rate in Co/Nb-CeO₂ Catalysts for Higher Water–Gas Shift Performance

Negi,

Kim,

Cheon

et al. 2023

ACS Appl. Mater. Interfaces

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H 2 production via water−gas shift reaction (WGS) is an important process and applied widely. Cobalt-modified CeO 2 are promising catalysts for WGS reaction. Herein, a series of Co/Nb−CeO 2 catalysts were prepared by varying the rate of precipitant addition during the coprecipitation method and examined for hydrogen generation through WGS reaction. The rates of precipitant addition were 1, 5, 15, and 25 mL/min. We obtained ceria supported cobalt catalysts with different sizes and morphology such as 3, 8 nm nanoclusters, 30 nm cubic nanoparticles, and 50 nm hexagonal nanoparticles. The well dispersed small cobalt particles in Co/Nb-CeO 2 that was prepared at 5 mL/min titration rate exhibit strong interaction between cobalt oxide and CeO 2 that retards the reduction of CoO x producing Co−CoO x pairs. In contrast, 1-Co/Nb-CeO 2 and 25-Co/Nb-CeO 2 result in bigger and aggregated Co particles, resulting in fewer interfaces with CeO 2 . The Co 0 , Co δ+ , Ce 3+ , and O v species are responsible for improved reducibility in Co/Nb−CeO 2 catalysts and were quantitively measured using XPS, XAS, and Raman spectroscopy. The Co−CoO x interface assists dissociation of the H 2 O molecule; CO oxidation requires low activation energy and realizes a high turnover frequency of 9.8 s −1 . The 5-Co/Nb-CeO 2 catalyst achieved thermodynamic equilibrium equivalent CO conversion with efficient H 2 production during WGS reaction at a gas hourly space velocity of 315,282 h −1 . Successively, the 5-Co/ Nb-CeO 2 catalyst exhibited stable performance for straight 168 h attributed to stable CO−Co δ+ intermediate formation, achieving efficient inhibition of typical CO chemistry over the Co metal, suitable for hydrogen generation from waste derived synthesis gas.

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“…In stark strong contrast to these absorption measurements are the characteristics obtained from photocurrents spectra Figure 2e,f. While for the plain anatase the expected distinct onset of the photocurrent at energies of 3.12 eV corresponding to the bandgap is observed, for the powder produced at higher temperatures only a slight lowering of the band gap to 3.02 eV and 2.98 eV is observed 22,30,35,36 . That is, no visible light response can be detected for any of the samples.…”

Section: Figure 2 (A) Photocatalytic H2 Evolution From Powders Synthe...mentioning

confidence: 89%

Magnéli Phases Doped with Pt for Photocatalytic Hydrogen Evolution

Wierzbicka

Domaschke

Denisov

et al. 2019

ACS Appl. Energy Mater.

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Defined substoichiometric titanium oxides (TixO2x-1 with 3 ≤ x ≤ 10) called Magnéli phases have been investigated mostly for their unusual high conductivity and metal-like behavior. In photocatalysis, Magnéli phase containing titania particles have been reported to provide favorable charge separation resulting in enhanced reaction efficiency. In the current work we describe a onestep synthesis of Magnéli-containing mixed phase nanoparticles that carry directly integrated minute amounts of Pt. Phase optimized nanoparticles that contain only a few hundred ppm Pt are very effective photocatalysts for H2 evolution (they provide a 50-100 times higher H2 evolution than plain anatase loaded with a similar amount of Pt). These photocatalysts are synthesized in a setup combining a hot-wall reactor that is used for TiOx synthesis with a spark generator producing Pt nanoparticles. Different reactor temperatures result in various phase ratios between anatase and Magnéli phases. The titania nanoparticles (≈ 24 -53 nm) were characterized using XRD, HRTEM, XPS and EPR spectra as well as ICP-OES analysis. The best photocatalyst prepared at 900 ºC (which consists of mixed phase particles of 32% anatase, 11% rutile and 57% Magnéli phases loaded with 290 ppm of Pt) can provide a photocatalytic H2 evolution rate of ≈ 5432 μmol h −1 g −1

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Enhanced light harvesting and charge separation over wormhole mesoporous TiO_2−X nanocrystallites towards efficient hydrogen generation

Abstract: Improved visible light absorption by meso-TiO2−X materials compared to TiO2 for enhanced solar light harvesting.

Cited by 12 publications

References 57 publications

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

Restructuring Co–CoO_x Interface with Titration Rate in Co/Nb-CeO₂ Catalysts for Higher Water–Gas Shift Performance

Magnéli Phases Doped with Pt for Photocatalytic Hydrogen Evolution

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Enhanced light harvesting and charge separation over wormhole mesoporous TiO2−X nanocrystallites towards efficient hydrogen generation

Abstract: Improved visible light absorption by meso-TiO2−X materials compared to TiO2 for enhanced solar light harvesting.

Cited by 12 publications

References 57 publications

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

Restructuring Co–CoOx Interface with Titration Rate in Co/Nb-CeO2 Catalysts for Higher Water–Gas Shift Performance

Magnéli Phases Doped with Pt for Photocatalytic Hydrogen Evolution

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Enhanced light harvesting and charge separation over wormhole mesoporous TiO_2−X nanocrystallites towards efficient hydrogen generation

Restructuring Co–CoO_x Interface with Titration Rate in Co/Nb-CeO₂ Catalysts for Higher Water–Gas Shift Performance