Ordered gyroidal tantalum oxide photocatalysts: eliminating diffusion limitations and tuning surface barriers

Cherevan, Alexey; Robbins, Spencer; Dieterle, D. J.; Gebhardt, Paul; Wiesner, Ulrich; Eder, Dominik

doi:10.1039/c6nr04430a

Cited by 27 publications

(26 citation statements)

References 37 publications

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“…The use of well‐defined porous environments can be a facile means to control POM incorporation and thereby enable or disable specific catalytic reaction pathways, for example, using size selectivity of transition state geometry stabilization. [ 80,81 ]…”

Section: Substrate Effects and Functional Propertiesmentioning

confidence: 99%

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

et al. 2020

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POMs were studied as heterogeneous acid catalysts and oxidation catalysts. However, this approach is often affected by low specific surface areas, leading to reduced reactivity. [10] Later studies, therefore, pioneered the immobilization of POMs on high surfacearea substrates including porous silica and other metal oxides, [10] as well as more advanced materials such as carbon nanostructures [11] and metal-organic frameworks (MOFs). [9] This strategy can enable maximized exposure of the individual POM molecules to the reaction environment, and in addition, allows for facile separation by filtration or centrifugation. [12] While early studies on POM immobilization used heterogeneous supports for mechanical stabilization and maximized surface-area, more recent studies have moved toward added properties introduced by the support. These include light-absorption and charge transport by semiconductors (TiO 2 , CdSe, etc.), electrical conductivity (by carbons, metals, conductive polymers) as well as specific POM binding sites, as introduced in MOFs and organofunctionalized supports. Many contemporary studies in this field share a common interest in exploring the synergism between POM and substrate to tune and optimize reactivity and stability of the composite. The concept has been theoretically and experimentally described several decades ago as the so-called "microenvironment effect" (electronic charge enhancement) where entrapment of POM species in a 3D matrix has been shown to induce huge improvement of their electrocatalytic activity. [13][14][15] However, to-date, the understanding of the fundamental processes which govern synergism of POM-substrate interactions is still in its infancy, as mole cular-level understanding of these complex processes by experiment or theory is far from trivial. This is due to the vast number of materials combinations, which are currently studied, and is further complicated by the often unknown chemical structures of the POM-substrate interface which make theoretical studies difficult. Also, in situ/operando studies of these materials are still challenging, and instrumentational approaches to address these issues are still being developed and not widely available. Most current experimental studies, therefore, focus on macroscopic reactivity, while providing less insight into the underlying causes of the processes observed.This Progress Report aims at raising awareness of the vast benefits of exploring this under-researched area to enable full use of POM-substrate interactions including charge and energy transfer, band-gap, and frontier orbital alignment as well as interface design for stability and reactivity. These fundamental concepts can affect both the thermodynamics as well as the kinetics of the chemical processes studied so that new reactivity can be tailored by understanding of the interactions between POM and substrate. Given the fast-paced progress in the synthesis, application, and characterization of this materials class, this Progress Report will serve as a focal point for ...

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Section: Substrate Effects and Functional Propertiesmentioning

confidence: 99%

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

et al. 2020

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“…Synthesis of G A ‐TiO2 and G A ‐TNO1/3 : The mesoporous TiO 2 samples were synthesized using EISA as already described in literature for related inorganic materials. [12a,c,21] In summary, a 4.5 mass% ISO in THF abs solution was combined with a certain amount of a precursor solution containing THF abs , HCl, and Ti( i Prop) 4 — for the preparation of TNO1/3 Nb(OEt) 5 partially replaces the Ti( i Prop) 4 . The mixture was stirred for 3 h at room temperature, transferred into 5 mL PTFE beakers and placed on a hotplate (35 °C) covered with a glass dome.…”

Section: Methodsmentioning

confidence: 99%

“…TiO 2 was the first ordered mesoporous transition metal oxide and primarily synthesized for use in dye‐sensitized solar cells (DSSCs) . In contrast to, for instance, tantalum oxide (Ta 2 O 5 ), where extended crystalline domains have been reported (>25 nm), mesoporous anatase TiO 2 typically comprises of distinctly smaller crystallites (≈10 ± 5 nm) within the walls . This compartmentalization is highly interesting, considering that the materials resistivity, and thus charge mobility, notably depends on the crystalline nature (i.e., size, topology, degree) .…”

Section: Introductionmentioning

confidence: 99%

Ordered Mesoporous TiO₂ Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation

Dörr

Deilmann

Haselmann

et al. 2018

Advanced Energy Materials

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Pure and Nb‐doped TiO2 photocatalysts with highly ordered alternating gyroid architecture and well‐controllable mesopore size of 15 nm via co‐assembly of a poly(isoprene)‐block‐poly(styrene)‐block‐poly(ethylene oxide) block copolymer are synthesized. A combined effort by electron microscopy, X‐ray scattering, photoluminescence, X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory simulations reveals that the addition of small amounts of Nb results in the substitution of Ti4+ with isolated Nb5+ species that introduces inter‐bandgap states, while at high concentrations, Nb prefers to cluster forming shallow trap states within the conduction band minimum of TiO2. The gyroidal photocatalysts are remarkably active toward hydrogen evolution under UV and visible light due to the open 3D network, where large mesopores ensure efficient pore diffusion and high photon harvesting. The gyroids yield unprecedented high evolution rates beyond 1000 µmol h−1 (per 10 mg catalyst), outperforming even the benchmark P25‐TiO2 more than fivefold. Under UV light, the Nb‐doping reduces the activity due to the introduction of charge recombination centers, while the activity in the visible triple upon incorporation is owed to a more efficient absorption due to inter‐bandgap states. This unique pore architecture may further offer hitherto undiscovered optical benefits to photocatalysis, related to chiral and metamaterial‐like behavior, which will stimulate further studies focusing on novel light–matter interactions.

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“…Crossland et al successfully obtained a DG titania network replicated from block copolymer templates and demonstrated their possible use in a solid‐state dye‐sensitized solar cell . In addition, DG titania can also be used as a photocatalyst …”

Section: Toward New Syntheses and Applicationsmentioning

confidence: 99%

An Overview of Materials with Triply Periodic Minimal Surfaces and Related Geometry: From Biological Structures to Self‐Assembled Systems

2018

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Triply periodic minimal surface structures and related geometries are widely identified in many natural systems, such as biological membranes and biophotonic structures in butterfly-wing scales. Inspired by their marvelous and highly symmetrical structures and optimized physical properties, these structures have sparked immense interest for creating novel materials by extracting the design from nature. Significant progress has been made to understand these biological structures and fabricate artificial materials by top-down and bottom-up approaches for numerous applications in chemistry and materials science. Herein, research achievements, including theoretical and experimental discoveries, in both biological systems and the artificial synthesis of materials with triply periodic minimal surface structures and related materials are summarized. Recent developments in self-assembled lyotropic liquid crystal phases, block copolymer systems, and their inorganic replicas are discussed in detail.

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Ordered gyroidal tantalum oxide photocatalysts: eliminating diffusion limitations and tuning surface barriers

Cited by 27 publications

References 37 publications

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Ordered Mesoporous TiO₂ Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation

An Overview of Materials with Triply Periodic Minimal Surfaces and Related Geometry: From Biological Structures to Self‐Assembled Systems

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Ordered gyroidal tantalum oxide photocatalysts: eliminating diffusion limitations and tuning surface barriers

Cited by 27 publications

References 37 publications

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Polyoxometalates on Functional Substrates: Concepts, Synergies, and Future Perspectives

Ordered Mesoporous TiO2 Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation

An Overview of Materials with Triply Periodic Minimal Surfaces and Related Geometry: From Biological Structures to Self‐Assembled Systems

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Product

Resources

About

Ordered Mesoporous TiO₂ Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation