To address this, scientists investigated the systems of surface oxidation on Pt surface in alkaline media, a formerly uncharted avenue of research study. While studies have actually investigated the oxide formation and decrease on the Pt surface area in acidic media, few of them have addressed the same in alkaline media, present in fuel cells and electrolyzers with anion exchange membranes.Advancements in Alkaline Media ResearchTo address this gap, a team of scientists led by Professor Masashi Nakamura from the Graduate School of Engineering, Chiba University, Japan, dug deep into the oxide formation systems on Pt surface areas in alkaline media.” Studies have shown that a combination of vibrational spectroscopy and X-ray diffraction is efficient for clarifying surface area oxidation processes,” includes Prof. Nakamura.X-ray CTR revealed that oxide formation results in surface area buckling and Pt extraction. Notably, the team also discovered that the electrostatic repulsion between Raman-active (H2O) advertisement and surrounding Raman-active Oad assists in Pt extraction.Conclusion and Implications for Clean EnergyThese results suggest that interfacial cations play an essential role in oxide formation on Pt surfaces, which can be controlled by choosing proper cations.Elaborating on these outcomes, Prof. Nakamura remarks: “These insights are essential for understanding the surface area oxidation mechanisms and the EDL structure, which can be helpful for achieving steady and high-performance Pt electrocatalysts for use in next-generation electrochemical devices.
Interfacial modification utilizing hydrophilic/hydrophobic cations to control both electrochemical activity and stability of platinum electrode. Credit: Masashi Nakamura from Chiba University, modified Researchers illuminate systems for managing the surface area oxidation processes that impact the performance of platinum catalysts in alkaline media.Platinum (Pt) electrodes are essential for tidy power innovations like hydrogen fuel cells and electrolysis. Nevertheless, the surface area oxidation that occurs during such processes breaks down driver performance and stability. To address this, researchers investigated the mechanisms of surface area oxidation on Pt surface in alkaline media, a formerly undiscovered avenue of research. Their experiments revealed crucial insights that can assist in the development of next-generation drivers, leading the way for a carbon-neutral society.Hydrogen Fuel Cells and ElectrolysisThe pursuit of carbon neutrality drives the expedition of clean energy sources, with hydrogen fuel cells becoming a promising avenue. In these cells, hydrogen goes through an electrochemical reaction with oxygen to produce electricity and water. The reverse of this process, called electrolysis, can be used to split the abundantly offered water to produce hydrogen and oxygen. These 2 innovations can operate in tandem to offer a sustainable and tidy source of energy. A critical component in these two innovations is the platinum (Pt) electrode.Challenges in Fuel Cell TechnologyHydrogen fuel cells include two electrodes: an anode and a cathode, with an electrolyte in between them. Pt serves as a fundamental driver in low-temperature fuel cells, such as alkaline fuel cells and polymer electrolyte fuel cells (PEFCs). Pt has a high activity for the oxygen decrease reaction (ORR), which is important for fuel cells, in alkaline and acidic conditions at the operating voltage of PEFC cathodes. However, this also causes oxide formation on the surface area, which roughens and liquifies the Pt layer, eventually deteriorating the cathodes and affecting performance and stability.Understanding surface area oxide formation systems is thus essential for establishing Pt cathode catalysts that work well in alkaline conditions. Research studies have actually shown that the oxide development on the Pt surface area depends on the electrode capacity, the electrolyte, and the electrical double layer (EDL). While studies have actually investigated the oxide development and reduction on the Pt surface in acidic media, few of them have actually dealt with the very same in alkaline media, present in fuel cells and electrolyzers with anion exchange membranes.Advancements in Alkaline Media ResearchTo address this space, a team of researchers led by Professor Masashi Nakamura from the Graduate School of Engineering, Chiba University, Japan, dug deep into the oxide formation mechanisms on Pt surfaces in alkaline media.” In a previous study, we reported that interfacial hydrophobic ions with long alkyl chains can improve ORR. This recommends that it is possible to build an interfacial reaction field that not only triggers the ORR but also enhances the resilience of Pt electrodes by utilizing optimal interfacial ions,” explains Prof. Nakamura.The research study also included contributions from Dr. Tomoaki Kumeda and Professor Nagahiro Hoshi, both from the Graduate School of Engineering at Chiba University, in addition to Dr. Osami Sakata from the Center for Synchrotron Radiation Research at Japan Synchrotron Radiation Research Institute. Their findings have actually been published in the Journal of the American Chemical Society.Innovative Techniques and FindingsThe group examined the oxide development on the Pt (111) surface in alkaline liquid solutions including different cations, particularly Lithium cation (Li+), Potassium (K+) cation and Tetramethylammonium cation (TMA+), using sophisticated approaches like X-ray crystal truncation rod (CTR) scattering, gold nanoparticle-based surface-enhanced Raman spectroscopy (GNP-SERS), and infrared reflection absorption spectroscopy (IRAS).” Studies have actually shown that a combination of vibrational spectroscopy and X-ray diffraction works for elucidating surface area oxidation procedures,” adds Prof. Nakamura.X-ray CTR revealed that oxide formation results in surface area buckling and Pt extraction. SERS and IRAS measurements revealed the cation-dependent and potential formation of 3 oxide species, specifically infrared (IR)- active adsorbed hydroxide OH (OHad), Raman active adsorbed water (H2O) advertisement, and Raman-active oxygen (Oad). The team discovered that hydrophilic cations like Li+ stabilize IR-active OHad, thus preventing harmful oxide development, while moderate hydrophilicity of K+ has no protective effect.Interestingly, large hydrophobic cations such as TMA+ likewise decrease irreparable oxidation, similar to Li+. Notably, the team also found that the electrostatic repulsion in between Raman-active (H2O) ad and surrounding Raman-active Oad facilitates Pt extraction.Conclusion and Implications for Clean EnergyThese results suggest that interfacial cations play a necessary role in oxide formation on Pt surface areas, which can be managed by picking appropriate cations.Elaborating on these outcomes, Prof. Nakamura remarks: “These insights are crucial for comprehending the surface area oxidation mechanisms and the EDL structure, which can be advantageous for accomplishing steady and high-performance Pt electrocatalysts for usage in next-generation electrochemical devices.” Overall, this research study takes us a step further in accomplishing a zero-carbon future powered by clean and abundant hydrogen.Reference: “Surface Extraction Process During Initial Oxidation of Pt( 111 ): Effect of Hydrophilic/Hydrophobic Cations in Alkaline Media” by Tomoaki Kumeda, Kenshin Kondo, Syunnosuke Tanaka, Osami Sakata, Nagahiro Hoshi and Masashi Nakamura, 20 March 2024, Journal of the American Chemical Society.DOI: 10.1021/ jacs.3 c11334.