Designing Electrochemical Systems for Energy Conversion

  • Keisuke Obata

Student thesis: Doctoral Thesis

Abstract

Electrochemical water splitting to hydrogen and oxygen is an attractive approach to store and convert intermittent renewable energy sources. Energy efficient, cost effective and durable electrochemical systems are highly required. Firstly, CeOx coated oxygen evolution electrocatalysts were developed to improve the stability. Unique permselectivity of the CeOx layer was disclosed, which helps to prevent dissolution of active metal site. Because oxygen evolution reaction requires a higher overpotential than hydrogen evolution reaction, kinetically facile oxidation of soluble redox ions was proposed as an alternative anodic reaction, in which the oxidized redox ions can be used for succeeding homogeneous reactions, such as treatment of H2S. How to tune the thermodynamics and the diffusion of candidate redox ions is discussed for a desired application. In addition to the anodic reaction, cathodic hydrogen evolution reaction has to be optimized. To maximize hydrogen evolution performance in near-neutral pH buffered conditions, concentration overpotentials from local pH and hydrogen on a Pt cathode are distinguished by mass transport modelling. Finally, stand-alone module was developed to perform solar-driven redox-mediated H2S splitting to H2 and S under natural solar irradiation.
Date of AwardJun 2019
Original languageEnglish (US)
Awarding Institution
  • Physical Science and Engineering
SupervisorKazuhiro Takanabe (Supervisor)

Keywords

  • Electrochemistry, Energy conversion, Water splitting, Solar fuel

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