Hydrogen oxidation reaction in alkaline media: Relationship between electrocatalysis and electrochemical double-layer structure. (November 2017)

• Record Type: Journal Article
• Authors: Ramaswamy, Nagappan; Ghoshal, Shraboni; Bates, Michael K.; Jia, Qingying; Li, Jingkun; Mukerjee, Sanjeev
• Is Part Of: Nano energy. Volume 41(2017:Nov.)
• Page Start: 765
• Page End: 771
• Publication Date: 2017-11
• Subjects: Hydrogen oxidation reaction -- Alkaline electrocatalysis -- Alkaline membrane fuel cells -- Electrochemical double-layer structure -- Quasi-specific adsorption -- X-ray absorption spectroscopy; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2017.07.053
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Enhancing the sluggish kinetics of electrochemical hydrogen-oxidation reaction in high pH environments is of crucial importance considering its applications in alkaline-membrane fuel cells (AMFC) and regenerative hydrogen electrodes for energy storage. Alkaline H2 -oxidation to form water involves reaction between H-adsorbed intermediates and hydroxide anions wherein the nature/source of the latter plays a crucial role. Here, we take a systematic approach to understand why H2 -oxidation kinetics is slower in alkaline media compared to acid. While recently reported models focus on surface-adsorbate bond strength optimization, we herein show that the alkaline H2 -oxidation mechanism is fundamentally different due to a complex interplay between electrocatalysis and electrochemical double-layer structure. A heretofore unknown modern rendition of the double-layer structure is proposed wherein specifically adsorbed (M-OHad ) and quasi-specifically adsorbed (M-Had/upd … OHq-ad ) reactive hydroxide-species localized in the compact part of the electrochemical double-layer is shown to define H2 -oxidation kinetics on monometallic and bimetallic catalyst surfaces at high pH. Graphical abstract: Highlights: Fundamental mechanistic causes of sluggishness of HOR in alkaline electrolyte. Catalysis mechanisms and parameters to design non-precious electrocatalysts for HOR. Interplay between adsorbed intermediates in electrochemical double-layer structure.