Periodic Reporting for period 2 - SuN2rise (Solar driven electrochemical nitrogen fixation for ammonia refinery)
Période du rapport: 2022-08-01 au 2024-01-31
Solar energy driven processes with H2O, CO2 and N2 as basic feedstocks can produce “solar fuels” that could substitute their fossil-based counterparts. Recent techno-economic analysis outline that competitivity could be reached between 2025 and 2048 for all renewable energy production pathways passing through H2O, CO2 and N2.
The technological advances generated from SuN2rise project will represent a significant milestone in the field of electrochemical reduction processes, these latter being central in the current transition towards a sustainable chemical industry. The newly conceived Li-mediated concept for N2-to-NH3 conversion aims at facilitating the transition towards an economy based on NH3, electrochemically produced in a reactor that can be simply fed by renewable energy (to power the reduction process), water and air (as starting compound to produce NH3).
Nowadays, 200 million metric tons of NH3 are globally produced each year, making NH3 one of the top-3 largest-volume industrial chemicals worldwide produced. NH3 has always been used for the production of nitrogen fertilizers, the application of which is essential for continuous sustenance of bountiful crops; NH3 is also widely used to produce chemical compounds like explosives, plastics, synthetic fibers, resins and industrial refrigerant. At the same time, NH3 is increasingly recognized as an important sustainable fuel (as a H2 carrier) for global use in the future. Overall, applications of NH3 in heavy transport, power generation and distributed energy storage are being actively developed. Produced at scale, NH3 could replace a substantial fraction of current-day liquid fuel consumption, but this requires a new paradigm behind its production, such as the one proposed in SuN2rise.
The technological advances generated from SuN2rise project will represent a significant milestone in the field of electrochemical reduction processes, these latter being central in the current transition towards a sustainable chemical industry. The newly conceived Li-mediated concept for N2-to-NH3 conversion aims at facilitating the transition towards an economy based on NH3, electrochemically produced in a reactor that can be simply fed by renewable energy (to power the reduction process), water and air (as starting compound to produce NH3).
Nowadays, 200 million metric tons of NH3 are globally produced each year, making NH3 one of the top-3 largest-volume industrial chemicals worldwide produced. NH3 has always been used for the production of nitrogen fertilizers, the application of which is essential for continuous sustenance of bountiful crops; NH3 is also widely used to produce chemical compounds like explosives, plastics, synthetic fibers, resins and industrial refrigerant. At the same time, NH3 is increasingly recognized as an important sustainable fuel (as a H2 carrier) for global use in the future. Overall, applications of NH3 in heavy transport, power generation and distributed energy storage are being actively developed. Produced at scale, NH3 could replace a substantial fraction of current-day liquid fuel consumption, but this requires a new paradigm behind its production, such as the one proposed in SuN2rise.
In the M1-30 period, all of the three WPs have started, as detailed below.
WP1: Development of aqueous solar cells.
The team has been able to develop hybrid solar cells using only water and non-rare/heavy elements for electrodes and electrolytes design. An aqueous solar cell concept has been proposed, where the operating principle of dye-sensitized solar cells for the first time has come concretely close to the always cited “Nature’s photosynthesis”: the newly conceived device operates in 100% water-based electrolyte, organic sensitizers, and heavy/rare metals-free redox shuttles and cathodes. To achieve this goal, novel active materials properlies tuned to work in an aqueous environment have been designed, where the standard working mechanism of dye-sensitized solar cells has resulted strongly affected due to modified interfaces, wettability and electrochemistry. The main activities carried our can be summarized as follows:
- Task 1.1 - Design of hybrid transparent electrodes for anodes and cathodes. This activity has ended at M30, with the overall achievement of 6 different sensitized photoanodes and 5 alternatives to Pt-based cathodes, optimized to work well in aqueous environment and keeping ˃65% transparency.
- Task 1.2 - Formulation of aqueous electrolytes, for both liquid and quasi-solid state cells. Currently, 3 different polymeric electrolytes have been developed, all of them being able to guarantee solar cells stability upon time. In addition, design of experiments has been successfully used for the preparation of UV-prepared polymer electrolyte membranes that will guarantee a production of quasi-solid state electrolytes without the use of organic solvents, catalysts and separation steps.
- Task 1.3 - Performance optimization and stabilization: started in M16, the team has successfully developed a screen-printing technique to design large-area cells, to match the 10x10 cm scale targeted in the project. Also, a photovoltaic testing bench has been setup with possibility to fully characterize solar cells performance for long time and compliant with the IEC-normated tests.
Two papers have already been published (see 10.1021/acssuschemeng.1c01882 and 10.1016/j.mtsust.2022.100271).
WP2: Carrying out electrochemical N2 reduction
The main activity of the team is that of developing a platform of electrolytes and catalysts to achieve unprecedented Li-mediated N2 reduction into NH3. The core of the experimental work is based on the fact that Li reacts with N2 at ambient conditions to form Li3N, and its protonolysis leads to NH3. This is carried out exploiting one of the Holy Grail of the battery field, i.e. the Li-N2 battery, thus working with a system on which the PI has a recognized international reputation and expertise to face the challenge. This approach has started to be carried out following these tasks:
- Task 2.1 - Design of N2 fixation cell;
- Task 2.2 - Li+ conducting polymer electrolytes;
- Task 2.3 - Cathodic catalytic activity.
The first activity in the list is requiring considerable efforts, since the reaction yields are currently low and it is therefore necessary to build electrochemical cells perfectly isolated from traces of gases coming from outside. This also required the purchase of a specially-designed equipment for the fabrication of electrochemical cell prototypes, which are now reproducibly produced in the ERC laboratory.
The second point, i.e. the development of electrolytes, began with the exploration of salts and solvents formulations, their evaluation in a Li-N2 environment and basic electrochemical and physico-chemical characterization. In parallel, the team also began making polymer membranes capable of exhibiting mechanical, thermal and self-healing properties suitable for use in highly stable Li-N2 cells.
WP3: Evolving towards solar NH3 refinery
The main activity of the team is that of integrating solar cells (from WP1) and electrochemical reactors (from WP2) in a unique solar powered device producing NH3 and fertilizers. This approach has started to be carried out following these tasks:
- Task 3.1 - Design of integrated devices.
- Task 3.2 - Performance, stability and LCA.
- Task 3.3 - In situ production of fertilizers.
WP1: Development of aqueous solar cells.
The team has been able to develop hybrid solar cells using only water and non-rare/heavy elements for electrodes and electrolytes design. An aqueous solar cell concept has been proposed, where the operating principle of dye-sensitized solar cells for the first time has come concretely close to the always cited “Nature’s photosynthesis”: the newly conceived device operates in 100% water-based electrolyte, organic sensitizers, and heavy/rare metals-free redox shuttles and cathodes. To achieve this goal, novel active materials properlies tuned to work in an aqueous environment have been designed, where the standard working mechanism of dye-sensitized solar cells has resulted strongly affected due to modified interfaces, wettability and electrochemistry. The main activities carried our can be summarized as follows:
- Task 1.1 - Design of hybrid transparent electrodes for anodes and cathodes. This activity has ended at M30, with the overall achievement of 6 different sensitized photoanodes and 5 alternatives to Pt-based cathodes, optimized to work well in aqueous environment and keeping ˃65% transparency.
- Task 1.2 - Formulation of aqueous electrolytes, for both liquid and quasi-solid state cells. Currently, 3 different polymeric electrolytes have been developed, all of them being able to guarantee solar cells stability upon time. In addition, design of experiments has been successfully used for the preparation of UV-prepared polymer electrolyte membranes that will guarantee a production of quasi-solid state electrolytes without the use of organic solvents, catalysts and separation steps.
- Task 1.3 - Performance optimization and stabilization: started in M16, the team has successfully developed a screen-printing technique to design large-area cells, to match the 10x10 cm scale targeted in the project. Also, a photovoltaic testing bench has been setup with possibility to fully characterize solar cells performance for long time and compliant with the IEC-normated tests.
Two papers have already been published (see 10.1021/acssuschemeng.1c01882 and 10.1016/j.mtsust.2022.100271).
WP2: Carrying out electrochemical N2 reduction
The main activity of the team is that of developing a platform of electrolytes and catalysts to achieve unprecedented Li-mediated N2 reduction into NH3. The core of the experimental work is based on the fact that Li reacts with N2 at ambient conditions to form Li3N, and its protonolysis leads to NH3. This is carried out exploiting one of the Holy Grail of the battery field, i.e. the Li-N2 battery, thus working with a system on which the PI has a recognized international reputation and expertise to face the challenge. This approach has started to be carried out following these tasks:
- Task 2.1 - Design of N2 fixation cell;
- Task 2.2 - Li+ conducting polymer electrolytes;
- Task 2.3 - Cathodic catalytic activity.
The first activity in the list is requiring considerable efforts, since the reaction yields are currently low and it is therefore necessary to build electrochemical cells perfectly isolated from traces of gases coming from outside. This also required the purchase of a specially-designed equipment for the fabrication of electrochemical cell prototypes, which are now reproducibly produced in the ERC laboratory.
The second point, i.e. the development of electrolytes, began with the exploration of salts and solvents formulations, their evaluation in a Li-N2 environment and basic electrochemical and physico-chemical characterization. In parallel, the team also began making polymer membranes capable of exhibiting mechanical, thermal and self-healing properties suitable for use in highly stable Li-N2 cells.
WP3: Evolving towards solar NH3 refinery
The main activity of the team is that of integrating solar cells (from WP1) and electrochemical reactors (from WP2) in a unique solar powered device producing NH3 and fertilizers. This approach has started to be carried out following these tasks:
- Task 3.1 - Design of integrated devices.
- Task 3.2 - Performance, stability and LCA.
- Task 3.3 - In situ production of fertilizers.
The carried out activity concerns a research topic that has exploded since 2020, namely the production of ammonia and fertilizers by electrochemical means. Despite a lot of competition in the field, the ERC team has already achieved two important milestones of solid progress compared to the state of the art:
- Having demonstrated the functioning of solar cells operating in water and having as a central component a waste biomass (lignin), thus making the technology sustainable and compliant with the principles of circular economy.
- Having developed a polymeric electrolyte capable of conducting Li + ions in Li-N2 cells, but equally functioning in lithium batteries (a very strategic area within our continent). In particular, the team also developed a new testing protocol that allows to seriously assess the self-healing capacity of these membranes and show a quantitative correlation with electrochemical performance.
In the last semester, the research sector related to the electrochemical reduction of nitrogen has seen the emergence of a new strategy, namely the use of electrochemical cells operating in water and with the use of lithium salts as a performance booster. To this end, the ERC team has begun to consider this new experimental reality, conducting some preliminary experiments to evaluate its performance, sustainability and compatibility with the project objectives.
- Having demonstrated the functioning of solar cells operating in water and having as a central component a waste biomass (lignin), thus making the technology sustainable and compliant with the principles of circular economy.
- Having developed a polymeric electrolyte capable of conducting Li + ions in Li-N2 cells, but equally functioning in lithium batteries (a very strategic area within our continent). In particular, the team also developed a new testing protocol that allows to seriously assess the self-healing capacity of these membranes and show a quantitative correlation with electrochemical performance.
In the last semester, the research sector related to the electrochemical reduction of nitrogen has seen the emergence of a new strategy, namely the use of electrochemical cells operating in water and with the use of lithium salts as a performance booster. To this end, the ERC team has begun to consider this new experimental reality, conducting some preliminary experiments to evaluate its performance, sustainability and compatibility with the project objectives.