Photochemical hydrogen production based on HCOOH/CO2 cycle promoted by pentanuclear cobalt complex

2022 ◽  
Author(s):  
Takuya Akai ◽  
Mio Kondo ◽  
Yutaka Saga ◽  
Shigeyuki Masaoka

The first catalytic cycle for hydrogen production based on the photochemical two-electron reduction of carbon dioxide (CO2) and the dehydrogenation of formic acid at ambient temperature was demonstrated using a...

2021 ◽  
Author(s):  
Antoine Bohn ◽  
Juan José Moreno ◽  
Pierre Thuéry ◽  
Marc Robert ◽  
Orestes Rivada Wheelaghan

A pyrazole–based ligand substituted with terpyridine groups at the 3 and 5positions has been synthesized to form the dinuclear cobalt complex 1, that electrocatalytically reduces carbon dioxide (CO2) to carbon monoxide (CO) in the presence of Brønsted acids in DMF. Chemical, electrochemical and UV–vis spectro–electrochemical studies under inert atmosphere indicate a single 2 electron reduction process of complex 1 at first, followed by a 1 electron reduction at the ligand. Infrared spectro–electrochemical studies under CO2 and CO atmosphere allowed us to identify a reduced CO–containing dicobalt complex which results from the electroreduction of CO2. In the presence of trifluoroethanol (TFE), electrocatalytic studies revealed single–site mechanism with up to 94 % selectivity towards CO formation when 1.47 M TFE were present, at –1.35 V vs Saturated Calomel Electrode in DMF (0.39 V overpotential). The low faradaic efficiencies obtained (<50%) are attributed to the generation of CO–containing species formed during the electrocatalytic process, which inhibit the reduction of CO2.


Energy ◽  
1998 ◽  
Vol 23 (12) ◽  
pp. 1107-1112 ◽  
Author(s):  
Satoshi Kaneco ◽  
Ryosuke Iwao ◽  
Kenji Iiba ◽  
Kiyohisa Ohta ◽  
Takayuki Mizuno

2020 ◽  
Vol 56 (33) ◽  
pp. 4519-4522
Author(s):  
Yuki Sofue ◽  
Kotohiro Nomura ◽  
Akiko Inagaki

Light-active dinuclear iridium complexes catalyze the decomposition of formic acid to generate H2 under ambient temperature and base-free conditions. The catalyst activity is sensitive to light demonstrating the ON/OFF switching ability.


Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 664
Author(s):  
Keyi Tian ◽  
Ruonan Chen ◽  
Jiafang Xu ◽  
Ge Yang ◽  
Xintong Xu ◽  
...  

The lack of understanding of the radical reaction mechanism of Carbon dioxide (CO2) in photo- and electro-catalysis results in the development of such applications far behind the traditional synthesis methods. Using methylbenzophenone as the model, we clarify and compare the photo-enolization/Diels−Alder (PEDA) mechanism for photo-carboxylation and the two-step single-electron reduction pathway for electro-carboxylation with CO2 through careful control experiments. The regioselective carboxylation products, o-acylphenylacetic acid and α-hydroxycarboxylic acid are obtained, respectively, in photo- and electro-chemistry systems. On the basis of understanding the mechanism, a one-pot step-by-step dicarboxylation of o-methylbenzophenone is designed and conducted. Both the experimental results and related density functional theory (DFT) calculation verify the feasibility of the possible pathway in which electro-carboxylation is conducted right after photo-carboxylation in one vessel. This synthesis approach may provide a mild, eco-friendly strategy for the production of polycarboxylic acids in industry.


Synlett ◽  
2021 ◽  
Author(s):  
Kenji Kamada ◽  
Hiroko Okuwa ◽  
Taku Wakabayashi ◽  
Keita Sekizawa ◽  
Shunsuke Sato ◽  
...  

A novel mononuclear ruthenium (Ru) complex bearing a PNNP-type tetradentate ligand is introduced here as a self-photosensitized catalyst for the reduction of carbon dioxide (CO2). When the pre-activation of the Ru complex by reaction with a base was carried out, an induction period of catalyst almost disappeared and the catalyst turnover numbers (TONs) over a reaction time of 144 h reached 307 and 489 for carbon monoxide (CO) and for formic acid (HCO2H), respectively. The complex has a long lifespan as a dual photosensitizer and reduction catalyst, due to the sterically bulky and structurally robust (PNNP)Ru framework. Isotope labeling experiments under 13CO2 atmosphere indicate that CO and HCO2H were both produced from CO2.


2021 ◽  
Author(s):  
Lingfei Xu ◽  
Tianchen Cui ◽  
Juan Zhu ◽  
Xinkui Wang ◽  
Min Ji

Exploration of excellent performance catalysts for carbon dioxide (CO2) hydrogenation is essential for CO2 utilization. In this work, a series of PdAg nanoparticles (NPs) immobilized on various organic amines functionalized...


Nanoscale ◽  
2021 ◽  
Author(s):  
Henglei Jia ◽  
Yanrong Dou ◽  
Yuanyuan Yang ◽  
Fan Li ◽  
Chun-Yang Zhang

Photocatalytic conversion of carbon dioxide (CO2) to liquid product acetaldehyde (CH3CHO) remains a great challenge due to the involvement of complex 10-electron reduction process and sluggish C–C coupling reaction. Herein,...


2018 ◽  
Author(s):  
Chandan Dey ◽  
Ronny Neumann

<p>A manganese substituted Anderson type polyoxometalate, [MnMo<sub>6</sub>O<sub>24</sub>]<sup>9-</sup>, tethered with an anthracene photosensitizer was prepared and used as catalyst for CO<sub>2</sub> reduction. The polyoxometalate-photosensitizer hybrid complex, obtained by covalent attachment of the sensitizer to only one face of the planar polyoxometalate, was characterized by NMR, IR and mass spectroscopy. Cyclic voltammetry measurements show a catalytic response for the reduction of carbon dioxide, thereby suggesting catalysis at the manganese site on the open face of the polyoxometalate. Controlled potentiometric electrolysis showed the reduction of CO<sub>2</sub> to CO with a TOF of ~15 sec<sup>-1</sup>. Further photochemical reactions showed that the polyoxometalate-anthracene hybrid complex was active for the reduction of CO<sub>2</sub> to yield formic acid and/or CO in varying amounts dependent on the reducing agent used. Control experiments showed that the attachment of the photosensitizer to [MnMo<sub>6</sub>O<sub>24</sub>]<sup>9-</sup> is necessary for photocatalysis.</p><div><br></div>


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