In this Application Note, a versatile and reliable measurement system for photoelectrochemical investigations is described which aims to assist scientists in obtaining reproducible photoelectrochemical data of high quality, including the solar-to-hydrogen (STH) efficiency. Specifically, it addresses the parameters irradiation quality, reaction temperature and gas measurement. The setup is designed to exclude stray light and uses a solar-grade mirror to reflect the light of a vertical solar simulator on the electrochemical cell. The light quality in the setup (»AAA«, IEC 60904-9) is close to the classification of the solar simulator itself. The temperature in the electrochemical cell is controlled with an external Peltier element and can be kept constant in the range of 20–45 °C. The influence of reaction temperature on the photocurrent of a WO 3 photoanode is demonstrated. The gaseous reaction products are analyzed with a mobile gas chromatograph, using an automated measurement routine with discontinuous sampling from the electrochemical cell. The system is applied to determine the Faraday and STH efficiencies of a copper indium gallium selenide photocathode.
The temperature has a large impact on the rate of a chemical reaction. For photoelectrochemical water splitting it has been shown that the photocurrent of a tungsten oxide anode increases by 64 % in a temperature interval of 25 to 65 °C. Photoelectrochemical cells are usually not equipped with systems for active temperature control. This limits the reliability of measurement data, especially for long measurements under illumination (e.g., impedance spectroscopy). Insufficient comparability of materials is an obstacle for development and application of photoelectrochemical modules.