| 1. |
- Axelsson, Martin, 1993-, et al.
(författare)
-
A benzothiadiazole based molecule for CO2 capture and reduction in multiple reduced states
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Using small organic molecular redox carriers to reversibly capture CO2 is a promising approach to mitigate the ongoing climate crisis. Some variants of this type of molecule can catalyse the reduction of CO2 into valuable chemicals. 2,1,3-benzothiadiazole (BT) is an interesting unit due to its proven interaction with CO2 upon reduction and the ease to tune its structure. In this work, the molecule 2,1,3-benzothiadiazole-4,7-dicarbonitrile (BTDN) is studied for CO2 and reduction at its different reduced states. The work is carried out with a combination of (spectro-)electrochemical and computational studies. In cyclic voltammetry, one can see a clear interaction between BTDN and CO2 upon BTDN’s second reduction and the appearance of a large current in its third reduction, in the presence of CO2. DFT calculations show a large variety of possible CO2-bound species that can potentially match the experimental data. The binding of CO2 on BTDN is shown to be irreversible upon the oxidation of the species, especially with low concentrations of CO2. From gas chromatography and NMR experiments, small amounts of CO and oxalate were detected after bulk electrolysis.
|
|
| 2. |
- Axelsson, Martin, 1993-
(författare)
-
Illuminating Benzothiadiazole : Mechanistic Insights into its Role in Fuel-Forming Reactions
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Development and understanding of catalytic reactions involved in fuel formation are crucial to be able to make the energy transition into a sustainable future. One intriguing type of catalyst for these types of reactions is organic material catalysts, which combine some of the tunable nature of molecular catalysts with the scalability and robust nature of material catalysts. The understanding of the catalytic mechanisms in these types of materials is still a work in progress. In the last decade D-A type polymers have gotten a lot of attention as potential photocatalysts for fuel-forming reactions but currently, the mechanisms in which these reactions take place are very limited.This thesis focuses on the molecular unit benzothiadiazole (BT) and its role in catalytic fuel-forming reactions across various molecules and polymers. In paper I: The hydrogen evolution reaction (HER) is investigated on the small molecule 2,1,3-benzothiadiazole-4,7dicarbonitrile (BT). The study reveals that BTDN serves as an electrocatalyst for the HER. Some catalytic intermediates were identified spectroscopically and a catalytic mechanism was proposed.In papers II and III: Polymeric nanoparticles (Pdots) based on the polymer poly(9,9- dioctylfluorene-alt-2,1,3-benzothiadiazole (PFBT) were investigated for photocatalytic fuel-forming reactions. First, the HER was explored and it emphasised the significance of proton binding to the BT unit as a catalytic intermediate. It also showed that changing to basic conditions can quench the HER and make place for CO2 reduction to CO and that PFBT Pdots exhibit good selectivity in catalyzing this reaction.Finally, in Paper IV, the binding and reduction of CO2 on the molecule BTDN were investigated. It was shown that BTDN can bind CO2 in multiple reduced states and reduce it to CO and oxalate in a third reduction, albeit with seemingly low efficiencies.
|
|
| 3. |
- Axelsson, Martin, 1993-, et al.
(författare)
-
The Role of Benzothiadiazole Unit in Organic Polymers on Photocatalytic Hydrogen Production
- 2024
-
Ingår i: JACS Au. - : American Chemical Society (ACS). - 2691-3704. ; 4:2, s. 570-577
-
Tidskriftsartikel (refereegranskat)abstract
- Organic polymers based on the donor–acceptor structure are a promising class of efficient photocatalysts for solar fuel production. Among these polymers, poly(9,9-dioctylfluorene-alt-1,2,3-benzothiadiazole) (PFBT) consisting of fluorene donor and benzothiadiazole acceptor units has shown good photocatalytic activity when it is prepared into polymer dots (Pdots) in water. In this work, we investigate the effect of the chemical environment on the activity of photocatalysis from PFBT Pdots for hydrogen production. This is carried out by comparing the samples with various concentrations of palladium under different pH conditions and with different sacrificial electron donors (SDs). Moreover, a model compound 1,2,3-benzothiadiazole di–9,9-dioctylfluorene (BTDF) is synthesized to investigate the mechanism for protonation of benzothiadiazole and its kinetics in the presence of an organic acid–salicylic acid by cyclic voltammetry. We experimentally show that benzothiadiazole in BTDF can rapidly react with protons with a fitted value of 0.1–5 × 1010 M–1 s–1 which should play a crucial role in the photocatalytic reaction with a polymer photocatalyst containing benzothiadiazole such as PFBT Pdots for hydrogen production in acidic conditions. This work gives insights into why organic polymers with benzothiadiazole work efficiently for photocatalytic hydrogen production.
|
|
| 4. |
- Cai, Bin, et al.
(författare)
-
Organic Polymer Dots Photocatalyst for CO2 Reduction in Aqueous Solution
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Developing low-cost and efficient photocatalysts to convert CO2 into valuable fuels is desirable to realize a carbon-neutral society. In this work, we report that polymer dots (Pdots) of poly[(9,9′-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-thiadiazole)] (PFBT) without adding any extra co-catalyst can photocatalytic reduction of CO2 into CO in aqueous solution, rendering a CO production rate of 57 μmol g-1 h-1 with a detectable selectivity of up to 100%. 5 cycles of CO2 re-purging experiments show no distinct decline in CO amount and reaction rate, indicating the promising photocatalytic stability of PFBT Pdots in photocatalytic CO2 reduction reaction. Mechanistic study reveals that photo-excited PFBT Pdots are reduced by TEOA first, then the reduced PFBT Pdots can bind CO2 and reduce it into CO via their intrinsic active sites. This work highlights the application of organic Pdots for CO2 reduction in the aqueous solution, which therefore provides a strategy to develop highly efficient and environmental-friendly nanoparticular photocatalysts for CO2 reduction.
|
|
| 5. |
- Cai, Bin, et al.
(författare)
-
Organic Polymer Dots Photocatalyze CO2 Reduction in Aqueous Solution
- 2023
-
Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 62:45
-
Tidskriftsartikel (refereegranskat)abstract
- Developing low-cost and efficient photocatalysts to convert CO2 into valuable fuels is desirable to realize a carbon-neutral society. In this work, we report that polymer dots (Pdots) of poly[(9,9 ' -dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-thiadiazole)] (PFBT), without adding any extra co-catalyst, can photocatalyze reduction of CO2 into CO in aqueous solution, rendering a CO production rate of 57 mu mol g(-1) h(-1 )with a detectable selectivity of up to 100 %. After 5 cycles of CO2 re-purging experiments, no distinct decline in CO amount and reaction rate was observed, indicating the promising photocatalytic stability of PFBT Pdots in the photocatalytic CO2 reduction reaction. A mechanistic study reveals that photoexcited PFBT Pdots are reduced by sacrificial donor first, then the reduced PFBT Pdots can bind CO(2 )and reduce it into CO via their intrinsic active sites. This work highlights the application of organic Pdots for CO2 reduction in aqueous solution, which therefore provides a strategy to develop highly efficient and environmentally friendly nanoparticulate photocatalysts for CO2 reduction.
|
|
