Search query: Sulfone-containing covalent organic frameworks  for photocatalytic hydrogen evolution from water

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abstract: AbstractNature uses organic molecules for light harvesting and photosynthesis, but most man made water splitting catalysts are inorganic semiconductors. Organic photocatalysts, while attractive because of their synthetic tunability, tend to have low quantum efficiencies for water splitting. Here we present a crystalline covalent organic framework (COF) based on a benzo bis(benzothiophene sulfone) moiety that shows a much higher activity for photochemical hydrogen evolution than its amorphous or semicrystalline counterparts. The COF is stable under long term visible irradiation and shows steady photochemical hydrogen evolution with a sacrificial electron donor for at least 50 hours. We attribute the high quantum efficiency of fused sulfone COF to its crystallinity, its strong visible light absorption, and its wettable, hydrophilic 3.2 nm mesopores. These pores allow the framework to be dye sensitized, leading to a further 61% enhancement in the hydrogen evolution rate up to 16.3 mmol g 1 h 1. The COF also retained its photocatalytic activity when cast as a thin film onto a support.The inherent synthetic tuneability of organic materials makes them attractive in photocatalysis, but they tend to have low quantum efficiencies for water splitting. A crystalline covalent organic framework featuring a benzo bis(benzothiophene sulfone) moiety has now been shown to exhibit high activity for photochemical hydrogen evolution from water.
author_names: Xiao-yan Wang

Linjiang Chen

Samantha Yu-Ling Chong

Marc A Little

Yongzhen Wu

Weihong Zhu

Rob Clowes

Yong Yan

Martijn A Zwijnenburg

Reiner Sebastian Sprick

Andrew I Cooper
title: Sulfone containing covalent organic frameworks for photocatalytic hydrogen evolution from water
venue: Nature Chemistry
year: 2018

abstract: A benzodifuran based donor acceptor covalent organic framework was synthesized and employed for efficient simulated sunlight driven photocatalytic hydrogen evolution from water, which exhibited a superior and steady hydrogen evolution rate of 1390 mmol g 1 h 1 and an outstanding apparent quantum yield (AQY) of 7.8% was obtained at 420 nm.
author_names: Fu-Cheng Zhu

Qian-Qian Lin

Jing-lan Kan

Ke-Hui Xie

Sha Li

Yan Geng

Yu-Bin Dong
title: Rational design of benzodifuran functionalized donor acceptor covalent organic frameworks for photocatalytic hydrogen evolution from water.
venue: Chemical communications
year: 2021

abstract: Visible light driven hydrogen (H2) production from water is a promising strategy to convert and store solar energy as chemical energy. Covalent organic frameworks (COFs) are front runners among different classes of organic photocatalysts. Photocatalytic activity of COFs depends on numerous factors such as electronic band gap, crystallinity, surface area, exci ton migration, stability of transient species, charge separation and transport, etc. However, it is challenging to fine tune all these factors simultaneously to enhance the photocatalytic activity. Hence, in this report, an effort has been made to understand the interplay of these factors and identify the key factors for efficient photocatalytic H2 production through structure property activity relationship. Careful molecular engineering allowed us to optimize all the above plausible factors impacting on the overall catalytic activities of a series of isoreticular COFs. The present study determines three prime factors: light absorption, charge carrier generation, and their transport, which influence the photocatalytic H2 production of COFs in much greater extent than the other factors.
author_names: Samrat Ghosh

Akinobu Nakada

Maximilian A Springer

Takahiro Kawaguchi

Katsuaki Suzuki

Hironori Kaji

Igor A Baburin

Agnieszka Beata Kuc

Thomas Heine

Hajime Suzuki

Ryu Abe

Shu Seki
title: Identification of Prime Factors to Maximize the Photocatalytic Hydrogen Evolution of Covalent Organic Frameworks.
venue: Journal of the American Chemical Society
year: 2020

abstract: Electron transfer is the rate limiting step in photocatalytic water splitting. Viologen and its derivatives are able to act as electron transfer mediators (ETMs) to facilitate the rapid electron transfer from photosensitizers to active sites. Nevertheless, the electron transfer ability often suffers from the formation of stable dipole structure through the coupling between cationic radical containing viologen derived ETMs, by which the electron transfer process becomes restricted. Herein, cyclic diquats, a kind of viologen derived ETM, are integrated into a 2,2' bipyridine based covalent organic framework (COF) through a post quaternization reaction. The content and distribution of embedded diquat ETMs are elaborately controlled, leading to the favorable site isolated arrangement. The resulting materials integrate the photosensitizing units and ETMs into one system, exhibiting the enhanced hydrogen evolution rate (34600 mmol h 1 g 1 and sustained performances when compared to a single module COF and a COF/ETM mixture. The integration strategy applied in a 2D COF platform promotes the consecutive electron transfer in photochemical processes through the multi component cooperation.
author_names: Zhen Mi

Ting Zhou

Weijun Weng

Junjuda Unruangsri

Ke Hu

Wuli Yang

Changchun Wang

Kai A I Zhang

Jia Guo
title: Covalent Organic Frameworks Enabling Site Isolation of Viologen Derived Electron Transfer Mediators for Stable Photocatalytic Hydrogen Evolution.
venue: Angewandte Chemie
year: 2021

abstract: Abstract A facile and effective impregnation combined with photo deposition approach was adopted to deposit cadmium sulfide (CdS) nanoparticles on CTF 1, a covalent triazine based frameworks (CTFs) In this system, CTF 1 not only acted as supporter but also served as photocatalyst and electron donor. The performance of the obtained CdS deposited CTF 1 (CdS CTF 1) nanocomposite was evaluated by H2 evolution reaction under visible light irradiation. As a result, CdS CTF 1 exhibited high H2 production from water, far surpassing the CdS/CTF 1 nanocomposite, in which CdS was deposited via solvothermal method. The high activity of CdS CTF 1 was attributed to the confined CdS nanoparticles with small size, leading to expose more active sites. In addition, time resolved spectroscopy indicated that the superior performance of CdS CTF 1 also can be ascribed to the fast electron transfer rate and injection efficiency (KET 0.18 x 109 s 1, einj 39.38% between CdS and CTF 1 layers, which are 3.83 times faster and 4.84 times higher than that of CdS/CTF 1 nanocomposite. This work represents the first example on using covalent organic frameworks (COFs) as a support and electron donor for fabricating novel CdS COF nanocomposite system and its potential application in solar energy transformations.
author_names: Dengke Wang

Hui Zeng

Xin Xiong

Mei-Feng Wu

Mei Ling Xia

Maoliang Xie

Jianping Zou

Shenglian Luo
title: Highly efficient charge transfer in CdS covalent organic framework nanocomposites for stable photocatalytic hydrogen evolution under visible light
year: 2020

abstract: Covalent organic frameworks have recently gained increasing attention in photocatalytic hydrogen generation from water. However, their structure property activity relationship, which should be beneficial for the structural design, is still far away explored. Herein, we report the designed synthesis of four isostructural porphyrinic two dimensional covalent organic frameworks (MPor DETH COF, M H2, Co, Ni, Zn) and their photocatalytic activity in hydrogen generation. Our results clearly show that all four covalent organic frameworks adopt AA stacking structures, with high crystallinity and large surface area. Interestingly, the incorporation of different transition metals into the porphyrin rings can rationally tune the photocatalytic hydrogen evolution rate of corresponding covalent organic frameworks, with the order of CoPor DETH COF H2Por DETH COF NiPor DETH COF ZnPor DETH COF. Based on the detailed experiments and calculations, this tunable performance can be mainly explained by their tailored charge carrier dynamics via molecular engineering. This study not only represents a simple and effective way for efficient tuning of the photocatalytic hydrogen evolution activities of covalent organic frameworks at molecular level, but also provides valuable insight on the structure design of covalent organic frameworks for better photocatalysis.
author_names: Rufan Chen

Yuan Ma

Arindam Mal

Xiaoya Gao

Lei Gao

Lijie Qiao

Xu-Bing Li

Li-Zhu Wu

Cheng Wang
title: Rational design of isostructural 2D porphyrin based covalent organic frameworks for tunable photocatalytic hydrogen evolution
venue: Nature communications
year: 2021

abstract: Efficient polymer photocatalysts that mimic natural photosynthesis to generate H2 through the visible light promoted splitting of water are ideal systems for the conversion of solar energy into usable fuel with high energy density and in an environmentally friendly manner. In this article, we review recent reports on donor acceptor based p conjugated polymers as photocatalysts, including conjugated linear polymers, microporous polymers, triazine frameworks, covalent organic frameworks, polymer dots, and other related organic polymers, which show superior photocatalytic activity and robust stability under visible light irradiation, for hydrogen production. Moreover, their syntheses and material design strategies, photophysical properties, proposed mechanisms, and applications are systematically summarized. Finally, recent research on and challenges related to organic polymer photocatalysts are discussed. This minireview will help readers to more easily understand the recent advances in and future direction of this field.
author_names: Jayachandran Jayakumar

Ho-Hsiu Chou
title: Recent Advances in Visible Light Driven Hydrogen Evolution from Water using Polymer Photocatalysts
year: 2020

abstract: Covalent triazine based frameworks (CTFs) are a subclass of conjugated microporous polymers (CMPs) that can be used as organic photocatalysts for photocatalytic hydrogen evolution from water. Seven materials with varied spacer units from phenylene to quarterphenylene were synthesized, either by trifluoromethanesulfonic acid (TfOH) catalysis from nitriles or by Suzuki Miyaura polycondensation. The photocatalytic performance under visible light of all materials was systematically studied in the presence of a hole scavenger, showing that both synthesis routes produce CTFs with similar hydrogen evolution rates (HER) but different optical properties. The highest hydrogen evolution rate in the cyclotrimerized series was found for CTF 2 with an apparent quantum yield of 1.6% at 420 nm in a mixture of water and triethanolamine with a platinum co catalyst. Based on (TD )DFT calculations, the highest performance was expected for CTF 1 and this discrepancy is explained by a trade off between increased light absorption and decreased thermodynamic driving force.
author_names: Christian B Meier

Reiner Sebastian Sprick

Adriano Monti

Pierre Guiglion

Jet-Sing M Lee

Martijn A Zwijnenburg

Andrew I Cooper
title: Structure property relationships for covalent triazine based frameworks: The effect of spacer length on photocatalytic hydrogen evolution from water
year: 2017

abstract: Solar hydrogen (H2) evolution from water utilizing covalent organic frameworks (COFs) as heterogeneous photosensitizers has gathered significant momentum by virtue of the COFs' predictive structural design, long range ordering, tunable porosity, and excellent light harvesting ability. However, most photocatalytic systems involve rare and expensive platinum as the co catalyst for water reduction, which appears to be the bottleneck in the development of economical and environmentally benign solar H2 production systems. Herein, we report a simple, efficient, and low cost all in one photocatalytic H2 evolution system composed of a thiazolo[5,4 d]thiazole linked COF (TpDTz) as the photoabsorber and an earth abundant, noble metal free nickel thiolate hexameric cluster co catalyst assembled in situ in water, together with triethanolamine (TEoA) as the sacrificial electron donor. The high crystallinity, porosity, photochemical stability, and light absorption ability of the TpDTz COF enables excellent long term H2 production over 70 h with a maximum rate of 941 mmol h 1 g 1, turnover number TONNi 103, and total projected TONNi 443 until complete catalyst depletion. The high H2 evolution rate and TON, coupled with long term photocatalytic operation of this hybrid system in water, surpass those of many previously known organic dyes, carbon nitride, and COF sensitized photocatalytic H2O reduction systems. Furthermore, we gather unique insights into the reaction mechanism, enabled by a specifically designed continuous flow system for non invasive, direct H2 production rate monitoring, providing higher accuracy in quantification compared to the existing batch measurement methods. Overall, the results presented here open the door toward the rational design of robust and efficient earth abundant COF molecular co catalyst hybrid systems for sustainable solar H2 production in water.
author_names: Bishnu P Biswal

Hugo A Vignolo-Gonzalez

Tanmay Banerjee

Lars Grunenberg

Gokcen Savasci

Kerstin Gottschling

Jurgen Nuss

Christian Ochsenfeld

Bettina V Lotsch
title: Sustained Solar H2 Evolution from a Thiazolo[5,4 d]thiazole Bridged Covalent Organic Framework and Nickel Thiolate Cluster in Water
venue: Journal of the American Chemical Society
year: 2019

abstract: The development of robust synthetic routes to stable covalent organic frameworks (COFs) is important to broaden the range of applications for these materials. We report here a simple and efficient three component assembly reaction between readily available aldehydes, amines and elemental sulfur via a C H functionalization and oxidative annulation under transition metal free conditions. Five thiazole linked COFs (TZ COFs) were synthesized using this method. These materials showed high levels of crystallinity, high specific surface areas, and excellent physicochemical stability. The photocatalytic applications of TZ COFs were investigated and TZ COF 4 gave high sacrificial hydrogen evolution rates from water (up to 4296 mmol h 1 g 1 under visible light irradiation) coupled with high stability and recyclability, with sustained hydrogen evolution for 50 hrs.
author_names: Kewei Wang

Zhifang Jia

Yang Bai

Xue Lian Wang

Sophie Hodgkiss

Linjiang Chen

Samantha Yu-Ling Chong

Xiao-yan Wang

Hao-Lin Yang

Yongjie Xu

Feng Feng

John W Ward

Andrew I Cooper
title: Synthesis of Stable Thiazole Linked Covalent Organic Frameworks via a Multicomponent Reaction.
venue: Journal of the American Chemical Society
year: 2020