scholarly journals Light-Driven Hydrogen Evolution Assisted by Covalent Organic Frameworks

Catalysts ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 754
Author(s):  
Nuria Romero ◽  
Roger Bofill ◽  
Laia Francàs ◽  
Jordi García-Antón ◽  
Xavier Sala
Keyword(s):  
Hydrogen Evolution ◽  
Charge Separation ◽  
Building Blocks ◽  
Covalent Organic Frameworks ◽  
Photocatalytic Efficiency ◽  
Co Catalyst ◽  
Co Catalysts ◽  
Separation Capacity ◽  
Metallic Compounds ◽  
Post Functionalization

Covalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units, such as triazine rings or diacetylene bridges. The bandgap, charge separation capacity, porosity, wettability, and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks, by extension of conjugation, by adjustment of the size and crystallinity of the pores, and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER), in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed, and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally, the aspects that need to be improved in the coming years will be discussed, such as the degree of dispersibility in water, the global photocatalytic efficiency, and the robustness and stability of the hybrid systems, putting emphasis on both the COF and the metal co-catalyst.

Boosting photocatalytic H2 evolution on g-C3N4 by modifying covalent organic frameworks (COFs)

2019 ◽  
Vol 55 (41) ◽  
pp. 5829-5832 ◽  
Author(s):  
Maolan Luo ◽  
Qing Yang ◽  
Kewei Liu ◽  
Hongmei Cao ◽  
Hongjian Yan
Keyword(s):  
Visible Light ◽  
Hydrogen Evolution ◽  
Quantum Efficiency ◽  
Covalent Organic Frameworks ◽  
H2 Evolution ◽  
Co Catalyst ◽  
Visible Light Driven ◽  
Apparent Quantum Efficiency ◽  
Sacrificial Agent ◽  
Photocatalytic H2 Evolution

Modifying g-C3N4 with covalent organic frameworks (COFs) through imine linkage results in a dramatically enhanced visible-light-driven photocatalytic hydrogen evolution, which reached 10.1 mmol g−1 h−1 when 2 wt% Pt and triethanolamine were used as co-catalyst and sacrificial agent, respectively, corresponding to an apparent quantum efficiency (AQE) of 20.7% at 425 nm.

scholarly journals 1T-phase MoS2 quantum dots as a superior co-catalyst to Pt decorated on carbon nitride nanorods for photocatalytic hydrogen evolution from water

2019 ◽  
Vol 3 (10) ◽  
pp. 2032-2040 ◽  
Author(s):  
Zhangqian Liang ◽  
Yichen Guo ◽  
Yanjun Xue ◽  
Hongzhi Cui ◽  
Jian Tian
Keyword(s):  
Quantum Dots ◽  
Hydrogen Evolution ◽  
Carbon Nitride ◽  
Co Catalyst ◽  
Photocatalytic Hydrogen Evolution ◽  
Co Catalysts

1T-MoS2 QDs exceed the performance of Pt as co-catalysts in assisting photocatalytic H2 evolution upon forming a heterostructure with C3N4 nanorods.

Size effect of Pt co-catalyst on photocatalytic efficiency of g-C3N4 for hydrogen evolution

2019 ◽  
Vol 464 ◽  
pp. 36-42 ◽  
Author(s):  
Yunqing Zhu ◽  
Tian Wang ◽  
Tao Xu ◽  
Yingxuan Li ◽  
Chuanyi Wang
Keyword(s):  
Size Effect ◽  
Hydrogen Evolution ◽  
Photocatalytic Efficiency ◽  
Co Catalyst

scholarly journals PEG-stabilized coaxial stacking of two-dimensional covalent organic frameworks for enhanced photocatalytic hydrogen evolution

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ting Zhou ◽  
Lei Wang ◽  
Xingye Huang ◽  
Junjuda Unruangsri ◽  
Hualei Zhang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Unique Feature ◽  
Layer By Layer ◽  
Two Dimensional ◽  
Covalent Organic Frameworks ◽  
Innovative Strategy ◽  
Photocatalytic Hydrogen Evolution ◽  
Visible Irradiation ◽  
Periodic Frameworks ◽  
Post Functionalization

AbstractTwo-dimensional covalent organic frameworks (2D COFs) featuring periodic frameworks, extended π-conjugation and layered stacking structures, have emerged as a promising class of materials for photocatalytic hydrogen evolution. Nevertheless, the layer-by-layer assembly in 2D COFs is not stable during the photocatalytic cycling in water, causing disordered stacking and declined activity. Here, we report an innovative strategy to stabilize the ordered arrangement of layered structures in 2D COFs for hydrogen evolution. Polyethylene glycol is filled up in the mesopore channels of a β-ketoenamine-linked COF containing benzothiadiazole moiety. This unique feature suppresses the dislocation of neighbouring layers and retains the columnar π-orbital arrays to facilitate free charge transport. The hydrogen evolution rate is therefore remarkably promoted under visible irradiation compared with that of the pristine COF. This study provides a general post-functionalization strategy for 2D COFs to enhance photocatalytic performances.

Black phosphorus: an efficient co-catalyst for charge separation and enhanced photocatalytic hydrogen evolution

2018 ◽  
Vol 53 (24) ◽  
pp. 16557-16566 ◽  
Author(s):  
Jiahao Wu ◽  
Shaolong Huang ◽  
Zhengyuan Jin ◽  
Jiaqi Chen ◽  
Liang Hu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Charge Separation ◽  
Black Phosphorus ◽  
Co Catalyst ◽  
Photocatalytic Hydrogen Evolution

Boosting visible-light hydrogen evolution of covalent-organic frameworks by introducing Ni-based noble metal-free co-catalyst

2020 ◽  
Vol 379 ◽  
pp. 122342 ◽  
Author(s):  
Hong Dong ◽  
Xiang-Bin Meng ◽  
Xin Zhang ◽  
Hong-Liang Tang ◽  
Jun-Wang Liu ◽  
...  
Keyword(s):  
Visible Light ◽  
Hydrogen Evolution ◽  
Noble Metal ◽  
Covalent Organic Frameworks ◽  
Co Catalyst ◽  
Metal Free

scholarly journals Donor-Acceptor Polymer Networks from Triarylborane and Thiophene Building Blocks for Photocatalytic Hydrogen Evolution from Aqueous Solution

2021 ◽  
Author(s):  
Matthias Trunk ◽  
Guiping Li ◽  
David Burmeister ◽  
Martin Obermeier ◽  
Boubacar Tanda Bonkano ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Electron Acceptor ◽  
Polymer Networks ◽  
Building Blocks ◽  
Photoexcited Electron ◽  
Co Catalyst ◽  
Synthetic Strategy ◽  
Microporous Polymer ◽  
Donor Acceptor ◽  
Band Gap Tuning

Photocatalytic water-splitting provides a carbon-neutral alternative to energy-intensive electrolysis to store solar energy in the form of hydrogen. Microporous polymer networks are an intriguing platform for the design of increasingly more performant photocatalysts due to their chemical modularity and band-gap tuning potential. Their efficacy depends on the efficient separation of photoexcited electron-hole pairs. Conventionally, this is achieved by deposition of expensive platinum as co-catalyst. More recently, however, it was recognized that efficiency of polymer photocatalysts can be improved by incorporation of donor-acceptor motifs into their backbones. While electron donors are plentiful, there is little variety in electron acceptor motifs. We synthesised a series of microporous donor-acceptor networks that contain electron-deficient triarylborane moieties with the unique electronic properties of tricoordinate boron as an electron acceptor. Under sacrificial conditions, these polymers feature hydrogen evolution rates of up to 113.9 mmol h-1 g-1 that decrease only marginally under omission of platinum co-catalyst. This work outlines a clear synthetic strategy towards truly noble-metal-free photocatalysts.

scholarly journals Exploration of the Photocatalytic Cycle for Sacrificial Hydrogen Evolution by Conjugated Polymers Containing Heteroatoms

2021 ◽  
Author(s):  
Andrew Prentice ◽  
Martijn Zwijnenburg
Keyword(s):  
Hydrogen Bond ◽  
Conjugated Polymers ◽  
Hydrogen Evolution ◽  
Noble Metal ◽  
Bond Formation ◽  
Metal Particles ◽  
Polymer Composition ◽  
Hydrogen Bond Formation ◽  
Co Catalyst ◽  
Co Catalysts

We analyze the photocatalytic activity of heteroatom containing linear conjugated polymers for sacrificial hydrogen evolution using a recently proposed photocatalytic cycle. We find that the thermodynamic barrier to electron transfer, relevant both in the presence and absence of noble metal co-catalysts, changes with polymer composition, reducing upon going from electron-rich to electron-poor polymers, and disappearing completely for the most electron-poor polymers in a water rich environment. We discuss how the latter is probably the reason why electron-poor polymers are generally more active for sacrificial hydrogen evolution than their electron-rich counterparts. We also study the barrier to hydrogen-hydrogen bond formation on the polymer rather than the co-catalyst and find that it too changes with composition but is always, at least for the polymer studied here, much larger than that experimentally reported for platinum. Therefore, it is expected that in the presence of any noble metal particles these will act as the site of hydrogen evolution.

Dibenzochrysene Enables Tightly Controlled Docking and Stabilizes Photoexcited States in Dual-Pore Covalent Organic Frameworks

2019 ◽  
Author(s):  
Torben Sick ◽  
Niklas Keller ◽  
Nicolai Bach ◽  
Andreas Koszalkowski ◽  
Julian Rotter ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Photophysical Properties ◽  
Visible Spectrum ◽  
Large Family ◽  
Building Blocks ◽  
Band Gaps ◽  
Docking Site ◽  
Covalent Organic Frameworks ◽  
Connected Node ◽  
Optoelectronic Applications

Covalent organic frameworks (COFs), consisting of covalently connected organic building units, combine attractive features such as crystallinity, open porosity and widely tunable physical properties. For optoelectronic applications, the incorporation of heteroatoms into a 2D COF has the potential to yield desired photophysical properties such as lower band gaps, but can also cause lateral offsets of adjacent layers. Here, we introduce dibenzo[g,p]chrysene (DBC) as a novel building block for the synthesis of highly crystalline and porous 2D dual-pore COFs showing interesting properties for optoelectronic applications. The newly synthesized terephthalaldehyde (TA), biphenyl (Biph), and thienothiophene (TT) DBC-COFs combine conjugation in the a,b-plane with a tight packing of adjacent layers guided through the molecular DBC node serving a specific docking site for successive layers. The resulting DBC-COFs exhibit a hexagonal dual-pore kagome geometry, which is comparable to COFs containing another molecular docking site, namely 4,4′,4″,4‴-(ethylene-1,1,2,2-tetrayl)-tetraaniline (ETTA). In this context, the respective interlayer distances decrease from about 4.60 Å in ETTA-COFs to about 3.6 Å in DBC-COFs, leading to well-defined hexagonally faceted single crystals sized about 50-100 nm. The TT DBC-COFs feature broad light absorption covering large parts of the visible spectrum, while Biph DBC-COF shows extraordinary excited state lifetimes exceeding 10 ns. In combination with the large number of recently developed linear conjugated building blocks, the new DBC tetra-connected node is expected to enable the synthesis of a large family of strongly p-stacked, highly ordered 2D COFs with promising optoelectronic properties.

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