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).