Automated GC measurement routine for STH determination
The desired product of an electrochemical reaction is measured
quantitatively for the determination of the Faraday efficiency, which is
an important parameter of an electrode/electrolyte combination. Side
reactions (e.g ., with the electrolyte) or subsequent reactions
(e.g ., with cell components) result in a Faraday efficiency below
100 %. In photoelectrochemical water splitting, quantitative
determination of hydrogen and oxygen has been carried out with mass
spectrometers [14] or with electrochemical sensors [15], but the
most common way is to measure with gas chromatographs. The integration
of gas chromatographs is a demanding task, as leakage can be a serious
problem. The accuracy is often limited by low gas amounts and by the
accuracy of supporting measuring devices (e.g. , volume flow
controllers).
The presented test setup aims to mitigate these problems by the use of a
commercial mobile GC which was optimized by the manufacturer for PEC
applications. The TC is equipped with an integrated Ar tank, a thermal
conductivity detector and two short columns to allow fast measurements.
It is connected to a Porto cell via metal gas transfer lines with
standard metric threads. A pressure sensor and a safety valve are
connected as well (Figure 4).