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Advanced catalyst electrodes from Ionic liquid modified PtNi nanowire arrays for PEFCs

Periodic Reporting for period 1 - IonPEFC (Advanced catalyst electrodes from Ionic liquid modified PtNi nanowire arrays for PEFCs)

Reporting period: 2017-08-03 to 2019-08-02

The fuel cell is a clean power generator with high energy efficiency and low carbon emission which can play a significant role in helping decarbonize power generation and transport sectors to meet Europe’s energy, environmental and economic challenges. It is estimated that the global fuel cell market could be worth over £16.7 billion in 2020 and over £115.4 billion in 2050. However, to make this clean technology really affordable, there are still major technical barriers to overcome. For polymer electrolyte fuel cells (PEFCs), these challenges still lie on the low activity, poor durability and high cost of electrocatalysts in cathodes toward oxygen reduction reaction (ORR). Therefore, IonPEFC proposes to develop, evaluate, and apply a new generation of catalyst electrodes with thin film catalyst nanostructures from PtNi nanowire arrays modified with protic ionic liquids (ILs) for high performance, robust and low cost PEFCs that can meet the targets for commercial applications in power generators and transport.
During the research period, the electrodes with thin film catalyst nanostructures from PtNi nanowire arrays (PtNi NW) were developed. Both ethylene glycol method and formic acid reduction method were explored. The effects of post acid washing and annealing on the surface properties of PtNi NW gas diffusion electrodes (GDEs) were investigated. The optimal PtNi NW GDEs showed a slightly improved power performance compared to the GDEs from the commercial Pt/C (TKK) nanoparticle electrocatalysts. Serval different types of hydrophobic ILs were synthesized, and well-tuned in physicochemical properties and functionalities and used to modify PtNi NW, Pt NW and Pt/C nanoparticle electrodes. The modification process was carefully studied. The power performance and durability of the as-prepared electrodes were then evaluated in single PEMFCs and compared. The final results showed that the IL modification effectively improved the power performance of PtNW and Pt/C electrodes, but the enhancement in the stability is limited. Regarding the PtNi NW electrodes, the modification by ILs showed only a very small enhancement in its power performance, which can be ascribed to the . The mechanisms behind were explored.

In addition to the work originally proposed, an alternative more promising work was conducted on using ILs to modify platinum group metal (PGM) free ZnCo-N-C electrocatalysts. The half-cell electrochemical measurement and in-situ test in fuel cells showed that the IL modification could effectively protect ZnCo-N-C electrocatalysts from corrosion in the acidic environment, showing 140% higher power density in fuel cell operation.

A few presentations have been gave at international conferences and workshops. Two papers have been published on related results (Front. Chem. Sci. Eng. 2019, doi:10.1007/s11705-019-1838-8; ACS Energy Lett., 2019, 4(9), 2104-2110, doi: 10.1021/acsenergylett.9b01407) and two others are still under preparation.
This is the first time using ionic liquids to modify one-dimensional nanostructure electrodes and platinum group metal free (PGM-free) electrocatalysts for fuel cell applications. The progress and understanding achieved enhance innovation capacity of component and construction of catalyst electrodes and catalyst layer structures, and its potential promotion in EU will contribute to scientific and technological advances in PEFCs, nanomaterial science and IL application. The output will also help widen PEFC application, promoting its commercialization and reducing carbon emission and fossil energy consumption, making FC more attractive for potential exploiters and users of this clean technology.
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