(Digital Presentation) Improving Oxygen Evolution Reaction Performance and Durability Using Rhombic Dodecahedral Pt₃(Ni,X) Nanoparticles with Metal Oxide Supports

Abstract

The supply infrastructure and production of hydrogen remains a limiting aspect in the introduction of polymer electrolyte fuel cell (PEFC) technologies.[1] The creation of highly efficient electrocatalysts is limited by predominantly carbon-based support systems which corrode readily during the oxygen evolution reaction (OER).[2] In acidic environments, iridium and ruthenium electrocatalysts with unary, binary, and ternary compositions have been used to achieve excellent OER results, however, carbon corrosion remains an issue for performance over long periods of time. The objective of this work is to examine the effect of highly active ternary based Pt3(Ni,X) rhombic dodecahedral nanoframes loaded onto metal oxide supports. Novel platinum-based electrocatalysts have been developed to improve catalytic activity and overall durability in acidic environments. Of note is the creation of binary Pt3Ni in a rhombic dodecahedral shape with a Pt skin synthesized.[3] These nanoparticles demonstrate very high specific/mass activities and are comparably durable over 10,000 potential cycles. Previous work[4] has been able to recreate the Pt3Ni rhombic dodecahedron under different synthesis conditions allowing for more rapid manufacture. These nanoparticles were used in combination with nitrogen-doped carbon support to examine the effects of surface nitrogen as anchoring sites. Examination using XPS, electrochemical stripping, and SEIRAS shows that the nitrogen sites alter the d-band center of surface Pt in addition to creating a more homogenous distribution of the nanoparticles. The addition of a ternary element allows for additional fine tuning of the d-band center of platinum near the particle surface. The oxygen evolution reaction requires a higher potential range which leaves carbon-based support systems susceptible to corrosion.[2] Several metal oxide support systems have been investigated as potential candidates, with a particular focus on material conductivity. Antimony tin oxide (ATO) shows promise as a relatively conductive metal oxide support for OER applications.[2] Furthermore, ATO shows lower dissolution rates when compared to other tin oxides in similar acidic environments.[5] As mentioned, iridium and ruthenium are used predominantly for OER in acidic environments. Therefore, the ternary metal additions (X) used in this work include PtNiIr and PtNiRu based nanoframes. These nanoframes have been successfully loaded onto ATO metal oxide supports. These catalyst support systems show promising OER results, even when compared to carbon supported NFs, as well as excellent durability. Examination was done using Scanning Tunneling Electron Microscopy (STEM), X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), X-ray absorption spectroscopy (XAS), and rotating disk electrode (RDE) electrochemical measurement. This work could lead to significant improvements into electrocatalyst activity and durability which are necessary to implement PEFC technology onto a global scale. References [1] S. Choi et al. Advanced Functional Materials 30.38 (2020): 2003935. [2] A. Hartig-Weiss et al., ACS Applied Nano Materials 3.3 2185-2196 (2020) [3] C. Chen et al., Science, 343, 1339-1343 (2014). [4] M.Kato et al., ACS Omega, 3, 8, 9052–9059 (2018). [5] S. Geiger et al. Scientific reports 7.1 (2017): 1-7.