Monday, 14 October 2019
Grand Ballroom (The Hilton Atlanta)
One of the most promising fuels in the near future will be hydrogen which should produce only by water
electrolysis.1 Although the kinetics of the hydrogen oxidation/evolution reaction (HOR/HER) on platinum
are extremely fast in acidic media, its catalytic performance tremendously drops by two order of magnitudes
in alkaline media.2
To obtain kinetic parameters of electrochemical reactions, e.g. HOR/HER or oxygen reduction reaction
(ORR), rotating disc electrode (RDE) experiments are the main tool in electrochemistry nowadays.
Although the RDE experiments can be performed very easily, fast and cost-efficiently in the labs, reliable
and reproducible evaluation of catalytic performances of materials remain still a critical challenge. In
particular, various sources of impurities need to take into account and to be eliminated prior to
electrochemical measurements. Not till then, structure-activity relationship of electrochemical reactions can
successfully be uncovered. In this study, we discuss possible contamination on polycrystalline platinum
during HER/HOR in various alkaline electrolyte solutions (KOH, NaOH and LiOH). We evidently show
that the observed contamination is not caused by the used hydrogen (quality of 99.999% vs. 99.9999%) or
by glass corrosion which can be avoided by frequently exchange of electrolyte solution. More importantly,
we point out that trace metals stemmed from commercially available used electrolyte salts quickly deposit
on a pure platinum surface during the initial HOR/HER polarization measurements and dramatically
decrease the electrochemically active Pt surface area (HUPD). In addition, we determined the losses of
HUPD over a broad temperature range in KOH, NaOH and LiOH. Interestingly, by chronoamperometric
investigations on a platinum foil followed by surface-sensitive X-ray photoelectron spectroscopy (XPS)
analysis we could detect qualitatively metal impurities originated from the electrolyte solution. We provide
a chronoamperometric method for further purification of electrolyte solution to reduce the contamination
and thus the HUPD losses after the HOR/HER. In this talk, we show critical approaches and solutions
which enable reliable and reproducible HOR/HER activity measurements on platinum in alkaline media.
electrolysis.1 Although the kinetics of the hydrogen oxidation/evolution reaction (HOR/HER) on platinum
are extremely fast in acidic media, its catalytic performance tremendously drops by two order of magnitudes
in alkaline media.2
To obtain kinetic parameters of electrochemical reactions, e.g. HOR/HER or oxygen reduction reaction
(ORR), rotating disc electrode (RDE) experiments are the main tool in electrochemistry nowadays.
Although the RDE experiments can be performed very easily, fast and cost-efficiently in the labs, reliable
and reproducible evaluation of catalytic performances of materials remain still a critical challenge. In
particular, various sources of impurities need to take into account and to be eliminated prior to
electrochemical measurements. Not till then, structure-activity relationship of electrochemical reactions can
successfully be uncovered. In this study, we discuss possible contamination on polycrystalline platinum
during HER/HOR in various alkaline electrolyte solutions (KOH, NaOH and LiOH). We evidently show
that the observed contamination is not caused by the used hydrogen (quality of 99.999% vs. 99.9999%) or
by glass corrosion which can be avoided by frequently exchange of electrolyte solution. More importantly,
we point out that trace metals stemmed from commercially available used electrolyte salts quickly deposit
on a pure platinum surface during the initial HOR/HER polarization measurements and dramatically
decrease the electrochemically active Pt surface area (HUPD). In addition, we determined the losses of
HUPD over a broad temperature range in KOH, NaOH and LiOH. Interestingly, by chronoamperometric
investigations on a platinum foil followed by surface-sensitive X-ray photoelectron spectroscopy (XPS)
analysis we could detect qualitatively metal impurities originated from the electrolyte solution. We provide
a chronoamperometric method for further purification of electrolyte solution to reduce the contamination
and thus the HUPD losses after the HOR/HER. In this talk, we show critical approaches and solutions
which enable reliable and reproducible HOR/HER activity measurements on platinum in alkaline media.
References
1. M. T. M. Koper, Nature chemistry, 5, 255 EP - (2013).
2. J. Durst, A. Siebel, C. Simon, F. Hasché, J. Herranz and H. A. Gasteiger, Energy Environ. Sci.,
7(7), 2255–2260 (2014).