NANO2021-Nanoteknologi og nye materiale

Fuel cells are energy converting devices able to provide high power densities with zero emission of CO2 and other pollutants. Over the last decade, the technology has become mature and fuel cells are finding their way to the market in a wide range of application. Fuel cell technologies however, still show a high capital cost, in particular for the membrane, catalyst and precious metal coating for the proton exchange membrane (PEMFC) technology. The NEXTGAME project is an international project (M-era net), with partners from Norway, Taiwan and Israel, looking at taking the anion exchange membrane (AEMFC) technology to the next level. In common with the PEMFC, the AEMFC is an all-solid electrochemical device able to generate high power outputs. The difference being that the AEMFC is built around an alkaline, rather than acidic, electrolyte membrane. The higher pH environment gives some advantages over the acid PEMFC, in particular: i) the potential use of Non-PGM catalysts for the oxygen reduction reaction (ORR), ii) the potential use of lower cost materials for stack components and iii) a wider choice of fuels, including H2, ammonia, urea, and other nitrogen based fuels. The NEXTGAME project aims at developing new non-precious metal catalysts for both the anode and cathode catalyst layer (NTNU and SINTEF), new types of alkaline ionomers (TECHNION) and new types of gas diffusion layers (NCHU). Technion have achieved a considerable amount of progress in 2017, among other work, Technion has established a new methodology for testing anion exchange materials at different relative humidity and have published the results. The Norwegian partners SINTEF and NTNU have also established methodologies for testing catalysts in alkaline media. Finally, our Taiwanese partner, NCHNU, continues their work on new types of gas diffusion layers. The second face-to-face meeting will be held in Taiwan on September 18-21 2017. In 2018, the NEXTGAME project has achieved both some successes, as well as faced a few new challenges. SINTEF has developed a Cobalt-based catalyst for the oxygen reduction reaction (ORR) showing good catalytic activity, although not as good as Platinum. The main challenge has been to develop an efficient non-Platinum (non-Pt) and non-group metal (non-PGM) catalysts for the hydrogen oxidation reaction (HOR). NTNU, with the help of TECHNION, have placed a lot of efforts in developing novel non-PGM, Ni-based alloys with some success. These new nano-structured Ni-alloys have shown good performance towards the HOR. However, Palladium (Pd) based catalysts (non-Pt), e. g. Pd supported on Ceria are showing better performance. The plan for the end of 2018 and beginning of 2019 is to show the proof of concept of these new materials in real anion exchange membrane fuel cells (AEMFC). In 2019, the NEXTGAME project worked on integrating the developed catalysts into a real AEM fuel cell device. Catalysts from NTNU, SINTEF and TECHNION were sent to NCHU (Taiwan) for fuel cell testing and validation. The hydrothermally synthesized Co3O4 catalyst used from SINTEF, in combination with Pt/C as HOR catalyst showed good AEMFC performance (peak power density of 388 mW cm-2), while the same catalyst coupled with SINTEF's flame spray pyrolysis based Pd/CeO2 anode catalysts reaches peak power densities of 309 mW cm-2. Unfortunately, changing the anode to NTNU's nanostructured NiCo/C catalyst, the performance is significantly reduced. The NEXTGAME project is able to conclude that is indeed possible to develop high performing AEMFCs totally free from Pt; however, the challenge to achieve completely PGM-free AEMFCs still remains. A scientific paper has recently been published in Van Men Truong, Julian Richard Tolchard, Jørgen Svendby, Maidhily Manikandan, Hamish A. Miller, Svein Sunde, Hsiharng Yang, Dario R. Dekel and Alejandro Oyarce Barnett, Platinum and Platinum Group Metal-Free Catalysts for Anion Exchange Membrane Fuel Cells, Energies 2020, 13, 582; doi:10.3390/en13030582 The NEXTGAME project has achieved the following goals: *Establishing an excellent collaboration between SINTEF, NTNU, TECHNION and NCHU. The partners have not only transferred a large amount of knowledge about synthesis procedures, materials and testing results involving AEMFCs, but have also transferred samples, scientific personnel and organized several project meetings. *This joint work has resulted in the development of several methods to fabricating Pt-free catalysts for AEM fuel cells. Operating conditions and performance criteria for these newly developed MEA have been established and have shown that these catalysts have the potential to replace Pt-based fuel cells. *The materials developed within NEXTAGAME have properties that could lead to the use of these materials in other AEM applications such as AEM electrolysis, reversed electro dialysis, and CO2 electrochemical conversion.

NEXGAME has develop a new generation gas diffusion electrodes (GDEs) for Anion Exchange Membrane Fuel Cells (AEMFCs) and demonstrate improved efficiency while using sustainable and affordable materials. Including the development of active Non-Pt and non-PGM anode catalysts for the hydrogen oxidation reaction (HOR), development of Non-PGM Metal oxide-based cathode catalyst for the oxygen reduction reaction (ORR). Fabrication of gas diffusion layers (GDLs), specifically design to be used as substrates for AEMFCs gas diffusion electrodes (GDEs). However, NEXTGAME did not fully overcome the challenges involving the integration of these materials into fully functional GDEs with durable AEMFC operation. The project also aimed at pushing up the AEMFCs technology readiness level (TRL). However, the current status is still TRL2-3. Some of the materials and solutions developed within NEXTGAME have found direct applicability in AEM water electrolysers.

In common with the PEMFC, the AEMFC is an all-solid electrochemical device able to generate high power outputs. The difference being that AEMFCs are built around an alkaline, rather than acidic electrolyte membrane. The higher pH environment gives some advantages over the acid PEMFC, in particular: i) the potential use of Non-PGM catalysts for the oxygen reduction reaction (ORR), ii) the potential use of lower cost materials for stack components and iii) a wider choice of fuels, including H2, ammonia, urea, and other nitrogen based fuels. The slow progress of this technology to date has been due the poor stability of anion exchange membranes. Significant advances have recently been made regarding membrane stability, and consequently it is now recognized that the other AEMFC components, e. g. the electrodes also need to be improved. In order for the AEMFCs to become a commercially available energy converting devices, the following challenges are addressed within NEXTGAME: i) the anion conductive phase within the electrodes, also called ionomer, still suffers degradation, specially affecting the cathode side of the AEMFC and ii) the efficiency of the hydrogen oxidation reaction (HOR) at the anode falls well behind PEMFCs due to the slow kinetics of oxidation reaction in alkaline medium. NEXTGAME is very ambitious and its expected output is considerable advances in the materials and electrochemical performance of AEMFC electrodes, which will in turn push AEMFCs to reach higher TRLs (TRL=4-5). A high impact is anticipated and is it projected that the fuel cell market and major fuel cell material manufacturers will show increased interest in the technology. Finally, it is noted that alkaline electrochemistry is not confined to AEMFCs, and that the solutions developed within NEXTGAME will have direct applicability to other alkaline electrochemical technologies,e. g. electrolysers and batteries.