| Summary: |
The utilization of affordable and sustainable sources of energy has been a major worldwide concern, which has led to the implementation of several renewable energy systems in many developed countries. However, such systems are not enough to face the energy demand, and more advanced technologies are required. The use of hydrogen as an energy vector is an interesting alternative to face the European energy demand, as it can be obtained by splitting water in an electrolyser (EL) and then be transformed into electricity in a fuel cell (FC). The combination of these two devices to implement a unique and revolutionary technology known as a Unitized Regenerative Fuel Cell (URFC), may transform the global energy production systems.
Nowadays, the proton-exchange membrane (PEM) is the dominating technology in EL and FC due to its great development in the aerospace industry. However, despite their continuously improving performance, PEM has not yet found a full commercial success due to the insufficient durability and high cost of the electrocatalysts. The most efficient electrocatalysts to date are based on noble metals, which are costly and scarce, and may assume up to 50% of the total cost of a cell. Thus, replacing noble metals by materials with lower cost, broader availability and efficient electroactivity is crucial to implement a real hydrogen economy. The main drawback of noble-metal-free electrocatalysts is that they exhibit far less efficient performance in PEMs, due to the acidic nature of the membranes, making chemical operational changes essential. One innovative strategy involves the transition from acidic to alkaline membranes (anion-exchange membranes (AEM)). The research on AEMs started just one decade ago, so AEMs are still a developing technology in which the design of the electrocatalyst, as well as the transfer of technology from the laboratory tests (TRL3) to the validation in a prototype cell (TRL4), are the major challenges.
The research team, base  |
Summary
The utilization of affordable and sustainable sources of energy has been a major worldwide concern, which has led to the implementation of several renewable energy systems in many developed countries. However, such systems are not enough to face the energy demand, and more advanced technologies are required. The use of hydrogen as an energy vector is an interesting alternative to face the European energy demand, as it can be obtained by splitting water in an electrolyser (EL) and then be transformed into electricity in a fuel cell (FC). The combination of these two devices to implement a unique and revolutionary technology known as a Unitized Regenerative Fuel Cell (URFC), may transform the global energy production systems.
Nowadays, the proton-exchange membrane (PEM) is the dominating technology in EL and FC due to its great development in the aerospace industry. However, despite their continuously improving performance, PEM has not yet found a full commercial success due to the insufficient durability and high cost of the electrocatalysts. The most efficient electrocatalysts to date are based on noble metals, which are costly and scarce, and may assume up to 50% of the total cost of a cell. Thus, replacing noble metals by materials with lower cost, broader availability and efficient electroactivity is crucial to implement a real hydrogen economy. The main drawback of noble-metal-free electrocatalysts is that they exhibit far less efficient performance in PEMs, due to the acidic nature of the membranes, making chemical operational changes essential. One innovative strategy involves the transition from acidic to alkaline membranes (anion-exchange membranes (AEM)). The research on AEMs started just one decade ago, so AEMs are still a developing technology in which the design of the electrocatalyst, as well as the transfer of technology from the laboratory tests (TRL3) to the validation in a prototype cell (TRL4), are the major challenges.
The research team, based on their broad experience on carbon materials for energy applications, strongly believes that research on the development of novel and advanced carbon materials as electrodes for URFC, along with the revolutionary technology of the AEMs, is expected to be a crucial tipping-point for the renewable energy production, one of the key strategies in the Portuguese National Energy and Climate Plan (2021-2030).
Carbon materials as electrodes for URFC with AEM are very promising as they can mitigate the long-term-instability observed in alkaline media for transition metals and metal oxides. Besides, the physicochemical properties of carbon materials can be fine-tuned to improve their electroactivity towards the four electrochemical reactions that take place in a URFC (hydrogen oxidation (HOR), oxygen reduction (ORR) and evolution of hydrogen (HER) and oxygen (OER)). HOR/HER and ORR/OER take place alternatively in the same electrode, so the research on this field should be focused on the design of bifunctional electrocatalysts with high electroactivity. The most promising strategy to improve the electroactivity is modulating the electroneutrality by adding heteroatoms and/or metals. The efficacy of the active sites offered by heteroatoms and metals can be evaluated by density functional theory (DFT) calculations. DFT has been extensively used to assess the catalytic mechanism of materials functionalized with one or two heteroatoms and even doped with one metal. However, the synergetic contribution of heteroatom-metal or metal-metal species has been rarely investigated via theoretical calculations. Hence, it is mandatory to asses the origin of the synergistic contributions by applying DFT calculations to produce the next-generation of bifunctional electrocatalysts with efficient multi-active centres and high performance towards HOR/HER and ORR/OER.
The main objective of BiCat4Energy is to develop new, innovative and low-cost bifunctional electrocatalysts to be used in URFC prototypes based on AEMs with an electrochemical performance more exceptional or comparable to that of currently noble metal-based electrocatalysts employed in EL and FC. The novelty of BiCat4Energy lies in the use of DFT calculations to evaluate the synergetic effect between the different active-centres and the validation of the materials in prototype cells using AEMs. This innovative proposal will allow the design of materials with extraordinary properties that would be a definitive differential factor concerning the current materials available in the market of EL and FC. Besides, the results obtained from BiCat4Energy are as useful for URFC as for other energy systems such as metal-air batteries in which ORR/OER also take place. Moreover, this project falls within the ten key action areas (Action 5) of the European Strategic Energy Technology Plan: new materials and technologies for energy efficiency solutions. |