Electrolyte Engineering towards Efficient Water Splitting at Mild pH

Tatsuya Shinagawa; Marcus Tze-Kiat Ng; Kazuhiro Takanabe

doi:10.1002/cssc.201701266

Electrolyte Engineering towards Efficient Water Splitting at Mild pH

ChemSusChem. 2017 Nov 9;10(21):4155-4162. doi: 10.1002/cssc.201701266. Epub 2017 Sep 21.

Authors

Tatsuya Shinagawa^{1

2}, Marcus Tze-Kiat Ng¹, Kazuhiro Takanabe¹

Affiliations

¹ King Abdullah University of Science and Technology (KAUST), KAUST Catalysis Center and Physical Sciences and Engineering Division, 4700 KAUST, Thuwal, 23955-6900, Saudi Arabia.
² Present address: Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Vladmir-Prelog-Weg 1, CH-8093, Zurich, Switzerland.

PMID: 28846205
DOI: 10.1002/cssc.201701266

Abstract

The development of processes for the conversion of H₂ O and CO₂ driven by electricity generated by renewable means is essential to achieving sustainable energy and chemical cycles, in which the electrocatalytic oxygen evolution reaction (OER) is one of the bottlenecks. In this study, the influences of the electrolyte molarity and identity on the OER at alkaline to neutral pH were investigated at an appreciable current density of around 10 mA cm^-2 , revealing both the clear boundary of reactant switching between H₂ O/OH^- , owing to the diffusion limitation of OH^- , and the substantial contribution of the mass transport of the buffered species in buffered mild-pH conditions. These findings suggest a strategy of electrolyte engineering: tuning the electrolyte properties to maximize the mass-transport flux. The concept is successfully demonstrated for the OER, as well as overall water electrolysis in buffered mild-pH conditions, shedding light on the development of practical solar fuel production systems.

Keywords: electrocatalysis; energy conversion; heterogeneous catalysis; oxygen evolution; solar fuels.