Green Leaf to Inorganic Leaf: A Case Study of ZnO

Naveen, K.; Devaraji, Perumal; Gopinath, Chinnakonda S.

doi:10.1166/jnn.2016.12912

Cited by 15 publications

(8 citation statements)

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“…Any light scattered internally and within the film is eventually absorbed by the film, and this enhances light absorption. This is somewhat analogous to the phenomenon that occurs in natural green leaf due to nano-micro-porosity; however, in the case of particulate catalyst in suspension, this phenomenon does not occur. Instead, particulate catalysts predominantly promote light scattering, rather than light absorption .…”

Section: Resultssupporting

confidence: 51%

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Tudu

Nalajala

Reddy

et al. 2021

ACS Sustainable Chem. Eng.

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Developing highly efficient and affordable catalysts for solar hydrogen (H2) generation is crucial, and employing a cocatalyst from earth-abundant elements has a critical role to play. In this context, different compositions of earth-abundant Ni–Fe alloy (1:1, 1:3, and 3:1) have been prepared by hydrothermal method; subsequently, 1 wt % of these Ni–Fe cocatalysts were integrated with TiO2-P25 and thoroughly characterized. The resultant catalysts have been evaluated for solar H2 production, in powder and thin film forms, under one sun condition and in direct sunlight. Interestingly, all the catalysts in the thin film form exhibit superior hydrogen yield (HY), up to 27 times higher activity than its powder counterpart. Among the photocatalysts, Ni–Fe/TiO2 (3:1 = Ni/Fe; NFT31) composition exhibits the best HY in thin film (8.27 mmol·h–1·g–1) and exceeds all other compositions of catalyst. It is also to be reported that HY measured for the powder form with 1 mg shows 3–17 times higher activity than that measured with 25 mg. This is mainly attributed to effective solar light absorption with a smaller amount of photocatalyst either spread over large area in a thin film form or well-dispersed in suspension forms. Furthermore, the enhanced activity obtained with Ni–Fe/TiO2 photocatalysts is also ascribed to strong electronic integration of Ni–Fe cocatalyst with TiO2 and higher performance obtained with a thin film is attributed to increased charge carrier generation and subsequent charge separation and effective utilization. A decrease in work function of TiO2 by 0.6 eV was observed after its integration with cocatalyst in NFT31.

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Section: Resultssupporting

confidence: 51%

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Tudu

Nalajala

Reddy

et al. 2021

ACS Sustainable Chem. Eng.

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“…Although these aspects are similar to those of powder and thin film forms of any material, 1–1.5 order of magnitude improvement in activity with thin film should necessarily involve increased absorption of light and subsequent increase in charge carriers. It is expected that internal light scattering within the thin film helps improve the net light absorption, as in natural green leaf. , This aspect is discussed in the next paragraph. Plasmonic metals can transfer the energy through field effect, which enhances the rate of formation of charge carrier in the semiconductor and rGO.…”

Section: Resultsmentioning

confidence: 99%

“…It is expected that internal light scattering within the thin film helps improve the net light absorption, as in natural green leaf. 51,52 This aspect is discussed in the next paragraph. Plasmonic metals can transfer the energy through field effect, which enhances the rate of formation of charge carrier in the semiconductor and rGO.…”

Section: Acs Applied Materials and Interfacesmentioning

confidence: 99%

Electronic Integration and Thin Film Aspects of Au–Pd/rGO/TiO₂ for Improved Solar Hydrogen Generation

Tudu

Nalajala

Reddy

et al. 2019

ACS Appl. Mater. Interfaces

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In the present work, we have synthesized noble bimetallic nanoparticles (Au–Pd NPs) on a carbon-based support and integrated with titania to obtain Au–Pd/C/TiO2 and Au–Pd/rGO/TiO2 nanocomposites using an ecofriendly hydrothermal method. Here, a 1:1 (w/w) Au–Pd bimetallic composition was dispersed on (a) high-surface-area (3000 m2 g–1) activated carbon (Au–Pd/C), prepared from a locally available plant source (in Assam, India), and (b) reduced graphene oxide (rGO) (Au–Pd/rGO); subsequently, they were integrated with TiO2. The shift observed in Raman spectroscopy demonstrates the electronic integration of the bimetal with titania. The photocatalytic activity of the above materials for the hydrogen evolution reaction was studied under 1 sun conditions using methanol as a sacrificial agent in a powder form. The photocatalysts were also employed to prepare a thin film by the drop-casting method. Au–Pd/rGO/TiO2 exhibits 43 times higher hydrogen (H2) yield in the thin film form (21.50 mmol h–1 g–1) compared to the powder form (0.50 mmol h–1 g–1). On the other hand, Au–Pd/C/TiO2 shows 13 times higher hydrogen (H2) yield in the thin film form (6.42 mmol h–1 g–1) compared to the powder form (0.48 mmol h–1 g–1). While powder forms of both catalysts show comparable activity, the Au–Pd/rGO/TiO2 thin film shows 3.4 times higher activity than that of Au–Pd/C/TiO2. This can be ascribed to (a) an effective separation of photogenerated electron–hole pairs at the interface of Au–Pd/rGO/TiO2 and (b) the better field effect due to plasmon resonance of the bimetal in the thin film form. The catalytic influence of the carbon-based support is highly pronounced due to synergistic binding interaction of bimetallic nanoparticles. Further, a large amount of hydrogen evolution in the film form with both catalysts (Au–Pd/C/TiO2 and Au–Pd/rGO/TiO2) reiterates that charge utilization should be better compared to that in powder catalysts.

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“…In comparison with TiO 2 , ZnO is a direct band-gap semiconductor with more oxygen vacancies on its surface, which benefits the formation of electron traps and prolongs the lifetime of charge carriers, thus absorbing a wider range of the solar spectrum [ 52 ]. Sathu et al [ 53 ] prepared inorganic leaves composed of ZnO by intercalating Zn 2+ ions into the porous channels of magnolia tree leaves (IL-ZnO). Compared with commercial ZnO, the amounts of defects related with the IL-ZnO were effectively suppressed.…”

Section: Heterogeneous Photocatalysts For Hydroxylation Of Benzene To...mentioning

confidence: 99%

Recent Advances in the Heterogeneous Photocatalytic Hydroxylation of Benzene to Phenol

et al. 2022

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Phenol is an important chemical material that is widely used in industry. Currently, phenol is dominantly produced by the well−known three−step cumene process, which suffers from severe drawbacks. Therefore, developing a green, sustainable, and economical strategy for the production of phenol directly from benzene is urgently needed. In recent years, the photocatalytic hydroxylation of benzene to phenol, which is economically feasible and could be performed under mild conditions, has attracted more attention, and development of highly efficient photocatalyst would be a key issue in this field. In this review, we systematically introduce the recent achievements of photocatalytic hydroxylation of benzene to phenol from 2015 to mid−2022, and various heterogeneous photocatalysts are comprehensively reviewed, including semiconductors, polyoxometalates (POMs), graphitic carbon nitride (g−C3N4), metal–organic frameworks (MOFs), carbon materials, and some other types of photocatalysts. Much effort is focused on the physical and chemical approaches for modification of these photocatalysts. The challenges and future promising directions for further enhancing the catalytic performances in photocatalytic hydroxylation of benzene are discussed in the end.

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Green Leaf to Inorganic Leaf: A Case Study of ZnO

Cited by 15 publications

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Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Electronic Integration and Thin Film Aspects of Au–Pd/rGO/TiO₂ for Improved Solar Hydrogen Generation

Recent Advances in the Heterogeneous Photocatalytic Hydroxylation of Benzene to Phenol

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Green Leaf to Inorganic Leaf: A Case Study of ZnO

Cited by 15 publications

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Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Rationally Designed, Efficient, and Earth-Abundant Ni–Fe Cocatalysts for Solar Hydrogen Generation

Electronic Integration and Thin Film Aspects of Au–Pd/rGO/TiO2 for Improved Solar Hydrogen Generation

Recent Advances in the Heterogeneous Photocatalytic Hydroxylation of Benzene to Phenol

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Electronic Integration and Thin Film Aspects of Au–Pd/rGO/TiO₂ for Improved Solar Hydrogen Generation