New reaction media for Solar Fuel production
Lead Research Organisation:
Swansea University
Department Name: College of Science
Abstract
The decreasing costs of solar and wind power have enabled a substantial growth in renewable electricity supply, however electricity makes up less than 25% of the world's energy demand. The major global energy demand is for fuels, and this demand is still predominantly met by fossil sources, because renewable fuel production is currently not competitive on price.
Clean H2 fuel can be sustainably generated by photochemically splitting water into H2 and O2, but the inevitable formation of O2 is limiting the overall efficiency of this process. Unless H2 and O2 production are spatially separated, the generated O2 suppresses H2 production. While such a separation is possible for electrolytic water splitting using ion-exchange membranes, albeit at added cost and complexity, there is no simple solution for photochemical H2 production, which is believed to offer the highest market potential for commercial solar fuel production.
This work aims to overcome these efficiency limitations through the design of novel reaction media. Water splitting is currently done in water as the solvent, but the high O2 solubility in water is problematic. Here, tailor-made non-aqueous reaction media will be developed to minimise O2 solubility, in order to suppress its detrimental effects and enable simple and robust solar fuel production at high efficiency. A range of organic solvents will be screened for their O2 solubility to establish structure-property relationships. The most promising solvents will be studied as reaction media for photocatalytic H2 generation in the presence of O2.
This project strongly aligns with the 'Hydrogen and alternative energy vectors' area of the EPSRC remit. By developing efficient ways to produce renewable H2 fuel at low cost using solar energy, this work directly addresses the National Renewable Energy Action Plan aiming to supply 10% of the UK's transportation fuel from renewable sources by 2020. It is also well aligned with the 'Sustainable Development' challenge of the UKRI global challenges fund, specifically aiming to provide 'equitable access to affordable, reliable, sustainable energy' through efficient low-cost generation of renewable fuels.
Clean H2 fuel can be sustainably generated by photochemically splitting water into H2 and O2, but the inevitable formation of O2 is limiting the overall efficiency of this process. Unless H2 and O2 production are spatially separated, the generated O2 suppresses H2 production. While such a separation is possible for electrolytic water splitting using ion-exchange membranes, albeit at added cost and complexity, there is no simple solution for photochemical H2 production, which is believed to offer the highest market potential for commercial solar fuel production.
This work aims to overcome these efficiency limitations through the design of novel reaction media. Water splitting is currently done in water as the solvent, but the high O2 solubility in water is problematic. Here, tailor-made non-aqueous reaction media will be developed to minimise O2 solubility, in order to suppress its detrimental effects and enable simple and robust solar fuel production at high efficiency. A range of organic solvents will be screened for their O2 solubility to establish structure-property relationships. The most promising solvents will be studied as reaction media for photocatalytic H2 generation in the presence of O2.
This project strongly aligns with the 'Hydrogen and alternative energy vectors' area of the EPSRC remit. By developing efficient ways to produce renewable H2 fuel at low cost using solar energy, this work directly addresses the National Renewable Energy Action Plan aiming to supply 10% of the UK's transportation fuel from renewable sources by 2020. It is also well aligned with the 'Sustainable Development' challenge of the UKRI global challenges fund, specifically aiming to provide 'equitable access to affordable, reliable, sustainable energy' through efficient low-cost generation of renewable fuels.
| Description | We have shown that the effects of oxygen on reaction systems for the production of hydrogen gas from sunlight can be mitigated. Oxygen in these reaction systems cause difficulty as they react with charge carriers, which lowers efficiency of hydrogen-producing mechanisms. Through our reaction design of using charged solvents for hydrogen production from sunlight, we show that oxygen diffusion and concentration is lowered, which enhances the hydrogen production activity in the presence of air. This allows us to design devices and reaction systems which prevent oxygen from sources (either from a leak or from oxygen generating mechanisms in the reaction) interacting with the hydrogen producing components, and enhancing the activity of materials and reactions for the production of renewable hydrogen gas. This approach has then been applied for biological catalysts which are typically de-activated by oxygen. We have shown that hydrogenase enzymes can retain activity for hydrogen evolution in air in our reaction systems to levels which have never been reported before. |
| Exploitation Route | This enables the further design of reaction environments for the production of hydrogen in aerobic conditions via catalysis. |
| Sectors | Chemicals,Energy |
| URL | https://pubs.rsc.org/en/content/articlehtml/2021/ee/d1ee01822a#:~:text=Here%2C%20we%20demonstrate%20efficient%20H%202%20evolution%20in,water%2C%20the%20same%20catalysts%20are%20almost%20entirely%20quenched. |
| Title | Dataset and collected data for publication of manuscript - Augmenting the Performance of Hydrogenase for Aerobic Photocatalytic Hydrogen Evolution via Solvent Tuning |
| Description | Collection of raw data from experiments based on hydrogen evolution from sunlight using biological hydrogenase catalysts. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | Shows that the activity of hydrogenase enzyme can be increased in aerobic conditions in deep eutectic solvents relative to a conventional aqueous solution. Also this work shows for the first time the use of hydrogenase enzymes for phtoocatalytic hydrogen evolution in organic-based solvents, highlighting the novelty and application of our reaction systems for methods of renewable hydrogen production |
| URL | https://zenodo.org/record/7573372#.ZA9l25HP02w |
| Title | Dataset and collected data for publication of manuscript - Solvent Controlled O2 Diffusion Enables Air-Tolerant hydrogen evolution |
| Description | Raw data collected from experimental analysis - uploaded to Zenodo under the publication with DOI:10.5281/zenodo.5236823 |
| Type Of Material | Database/Collection of data |
| Year Produced | 2021 |
| Provided To Others? | Yes |
| Impact | Allowed for the determination of solvent controlled oxygen diffusion for hydrogen evolution under aerobic conditions. Shows that rational solvent design can aid in increasing aerobic hydrogen evolution activity at photocatalysts inactive in the presence of oxygen |
| URL | https://zenodo.org/record/5236823#.ZA9g4JHP02x |
| Description | Project Collaboration with Swansea University for Photoelectrochemical Measurements |
| Organisation | Swansea University |
| Department | College of Science |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Provided equiment, time, and resources for the project. This involved using our analytical apparatus to irradiate materials and quantify hydrogen production. |
| Collaborator Contribution | Fabricated devices for hydrogen evolution |
| Impact | Published two papers (with another under review) in peer-reviewed journals. Enhanced knowledge of chemical processes and allowed for the improvement of experimental design and setup regarding water splitting reactions. |
| Start Year | 2019 |
| Description | Project Collaboration with Universite Grenobles Alpes for Enzyme Activity Determination |
| Organisation | University of Grenoble |
| Country | France |
| Sector | Academic/University |
| PI Contribution | Our role in the project was to test enzymes for photocatalysis. Enzymes (provided by the Universite Grenoble Alpes) were subject to irradiation in our reaction systems and the total hydrogen evolution activity quantified in our research facility. Writing a manuscript for publication |
| Collaborator Contribution | Produced enzyme batches for the project as well as key electrochemical measurements to aid in our understanding of mechanistic approaches in the reaction solvents. |
| Impact | A paper was published in 2023 as a result of the project. Future partnerships and projects have been proposed from the research. |
| Start Year | 2021 |
| Description | Project Collaboration with the University of Bath for Electrochemical Measurments |
| Organisation | University of Bath |
| Department | Department of Chemistry |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Personally visited the University of Bath to construct devices and electrodes for measuring oxygen concentration in solvents. Performed tests on our homemade devices to detect oxygen and entered fruitful discussions of results to aid in understanding the behaviour of oxygen in these solvents |
| Collaborator Contribution | Provided laboratory space and equipment, as well as materials, for the fabrication of these electrodes. Provided time and resources for discussions as well as proposed mechanisms for behaviour of the oxygen detected in our systems. |
| Impact | The collaboration aided in our understanding of the behaviour of dissolved oxygen in solvents applied for photocatalytic purposes. Enhanced the design of reactions through discussions which enabled us to publish with higher impact as a result of these discussions. |
| Start Year | 2020 |