Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences

Ebihara, Makoto; Ikeda, Takeshi; Okunaka, Sayuri; Tokudome, Hiromasa; Domen, Kazunari; Katayama, Kenji

doi:10.1038/s41467-021-24061-4

Cited by 50 publications

(45 citation statements)

References 54 publications

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“…The Raman spectrum of NiPS 3 UNSs (Supplementary Fig. 8a) exhibits the presence of E (2) g , A (1) 1g , A (2) 1g and A (3) 1g modes, in agreement with the prior report 60 . Moreover, the UV-Vis absorption spectrum of NiPS 3 UNSs (Supplementary Fig.…”

Section: Resultssupporting

confidence: 90%

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

Ran

Zhang

et al. 2022

Nat Commun

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High-performance and low-cost photocatalysts play the key role in achieving the large-scale solar hydrogen production. In this work, we report a liquid-exfoliation approach to prepare NiPS3 ultrathin nanosheets as a versatile platform to greatly improve the light-induced hydrogen production on various photocatalysts, including TiO2, CdS, In2ZnS4 and C3N4. The superb visible-light-induced hydrogen production rate (13,600 μmol h−1 g−1) is achieved on NiPS3/CdS hetero-junction with the highest improvement factor (~1,667%) compared with that of pure CdS. This significantly better performance is attributed to the strongly correlated NiPS3/CdS interface assuring efficient electron-hole dissociation/transport, as well as abundant atomic-level edge P/S sites and activated basal S sites on NiPS3 ultrathin nanosheets advancing hydrogen evolution. These findings are revealed by the state-of-art characterizations and theoretical computations. Our work for the first time demonstrates the great potential of metal phosphorous chalcogenide as a general platform to tremendously raise the performance of different photocatalysts.

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Section: Resultssupporting

confidence: 90%

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

Ran

Zhang

et al. 2022

Nat Commun

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“…This Z-scheme could be the main reason for composites showing better charge separation and transport properties. 24 The introduction of defect states in the forbidden gap reduces the recombination of the electron−hole pair (Figure S2b); however, the adsorbed species on defect sites such as hydroxyl groups can also contribute to arresting the recombination, which has previously been reported in a study. 25 The slight difference in recombination between 3NS and 3NSR can be reasoned by an increase in defect density in the latter (Figure 1d), which is attributed to surface dipoles.…”

Section: Resultsmentioning

confidence: 51%

“…The formation of the Z-scheme has its own advantages such as preserving high redox potentials and enhanced charge separation. This Z-scheme could be the main reason for composites showing better charge separation and transport properties …”

Section: Resultsmentioning

confidence: 93%

Effect of Defects on Optical, Electronic, and Interface Properties of NiO/SnO₂ Heterostructures: Dual-Functional Solar Photocatalytic H₂ Production and RhB Degradation

Maarisetty

Baral

2021

ACS Appl. Mater. Interfaces

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Photocatalytic H2 evolution and organic pollutant oxidation have witnessed a radical surge in recent times. However, this integration demands spatial charge separation and unique interface properties for a trade-off between oxidation and reduction reactions. In the current work, defect engineering of NiO/SnO2 nanoparticles aided in altering the optoelectronics and interface properties and enhanced photocatalytic activity. After annealing the catalysts in a N2 atmosphere, the hydroxyl groups were replaced by water molecules through surface modification. The photoexcited holes accumulated on SnO2 break the water molecules and facilitate the reduction of protons on NiO; this is known as spatial separation. Meanwhile, direct hole oxidation, an oxygen reduction reaction, ensures the degradation activity in this 2-fold system. By defect engineering, the limitations of SnO2 such as higher H2O adsorption, wide bandgap (reduced from 3.02 to 1.88 eV), and electronic properties were addressed. The H2 production in the current work has attained a value of 3732 μmol/(g h), which is 2.9 times that of the previous best reported under sunlight. Recyclability tests confirmed the stability of vacancies by promoting the reoxidation of defect states during photocatalytic activity. Additionally, efforts were made to study the effect of defect density on the photocurrent, the electrical resistance, and the mechanism of photocatalytic reactions. Electrochemical characterizations, UPS, XPS, UV-DRS, and PL were employed to understand the influence of defects on the bandgap, charge recombination, charge transport, charge carrier lifetime, and the interface properties that are responsible for photocatalytic activity. In this regard, it was understood that maintaining the optimal defect concentration is important for higher photocatalytic efficiencies, as the defect optimality preserves key photocatalytic properties. Apart from characterizations, the photocatalytic results suggest that excess defect density triggers the undesired thermodynamically favored back reactions, which greatly hampered the H2 yield of the process.

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“…As mentioned above, the heterojunction of type II is commonly proposed for the Bi 2 WO 6 –TiO 2 system ( Figure 9 a) but the energy bands of Bi 2 WO 6 are located lower than the bands of TiO 2 , which prevents the transfer of holes from TiO 2 . At the same time, the energy levels of nitrogen species in TiO 2 -N are located substantially higher than the VB of TiO 2 [ 54 ] and a Z-scheme heterojunction, when the photogenerated electrons from the CB of Bi 2 WO 6 would interact with the photogenerated holes from nitrogen levels of TiO 2 ( Figure 9 b), can be proposed for Bi 2 WO 6 –TiO 2 -N similarly to other systems [ 55 , 56 , 57 ]. Therefore, this junction can promote a removal of photogenerated holes from the nitrogen energy levels and suppress the degradation of nitrogen impurities by these holes.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Photocatalytic Activity and Stability of Bi2WO6 – TiO2-N Nanocomposites in the Oxidation of Volatile Pollutants

et al. 2022

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The development of active and stable photocatalysts for the degradation of volatile organic compounds under visible light is important for efficient light utilization and environmental protection. Titanium dioxide doped with nitrogen is known to have a high activity but it exhibits a relatively low stability due to a gradual degradation of nitrogen species under highly powerful radiation. In this paper, we show that the combination of N-doped TiO2 with bismuth tungstate prevents its degradation during the photocatalytic process and results in a very stable composite photocatalyst. The synthesis of Bi2WO6–TiO2-N composites is preformed through the hydrothermal treatment of an aqueous medium containing nanocrystalline N-doped TiO2, as well as bismuth (III) nitrate and sodium tungstate followed by drying in air. The effect of the molar ratio between the components on their characteristics and photocatalytic activity is discussed. In addition to an enhanced stability, the composite photocatalysts with a low content of Bi2WO6 also exhibit an enhanced activity that is substantially higher than the activity of individual TiO2-N and Bi2WO6 materials. Thus, the Bi2WO6–TiO2-N composite has the potential as an active and stable photocatalyst for efficient purification of air.

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Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences

Cited by 50 publications

References 54 publications

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

Effect of Defects on Optical, Electronic, and Interface Properties of NiO/SnO₂ Heterostructures: Dual-Functional Solar Photocatalytic H₂ Production and RhB Degradation

Enhanced Photocatalytic Activity and Stability of Bi2WO6 – TiO2-N Nanocomposites in the Oxidation of Volatile Pollutants

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Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences

Cited by 50 publications

References 54 publications

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

Effect of Defects on Optical, Electronic, and Interface Properties of NiO/SnO2 Heterostructures: Dual-Functional Solar Photocatalytic H2 Production and RhB Degradation

Enhanced Photocatalytic Activity and Stability of Bi2WO6 – TiO2-N Nanocomposites in the Oxidation of Volatile Pollutants

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Effect of Defects on Optical, Electronic, and Interface Properties of NiO/SnO₂ Heterostructures: Dual-Functional Solar Photocatalytic H₂ Production and RhB Degradation