Communication—Layered Double Hydroxide as Intermediate-Temperature Electrolyte for Efficient Water Splitting

Highly efficient electrolyzers will be a key component of our future energy infrastructure. An intermediate operating temperature between 100 °C and 250 °C could offer increased efficiency and advantages in system design. However, electrolytes for electrolysis in this temperature range have received little attention so far. In this study, layered double hydroxides are demonstrated as solid-state electrolytes for water splitting at an intermediate temperature of 146 °C and a remarkable gain in efficiency is observed with increasing temperature. This opens new opportunities for electrolyzers and other electrochemical devices in the promising intermediate temperature range

Study on solid electrolyte catalyst poisoning in solid acid fuel cells

Solid acid fuel cells operate at intermediate temperatures utilizing a solid electrolyte (CsH2PO4, CDP). However, relatively little is known about the degradation mechanism and the topic is rarely addressed. Phosphate poisoning of the platinum catalyst is a well-known problem for fuel cells working with H3PO4 as electrolyte. With CsH2PO4 as electrolyte, phosphate poisoning is therefore likely to occur as well. In this study we show a fast and reversible degradation behavior of solid acid fuel cells and associate it with poisoning of the catalyst. After a decline in power output of around 50% within hours, an in situ reactivation of the cell to almost the initial performance was possible by multiple cycling between the voltage of 0.1 V and 2.0 V. A limitation of the effect to the cathode is shown and the underlying process was analyzed by changes in the low frequency domain of impedance measurements, which is indicating a catalyst poisoning, and by the dependency from the upper vertex voltage. By employing a micro porous current collector, a decrease in the low frequency domain as well as enhanced stability (<125 μV h−1 at 0.43 V) was achieved. This work extends from a detailed insight in the degradation mechanism of solid acid fuel cells, to providing a working electrode modification to prevent poisoning, establishing a promising electrode stability on a laboratory scale

Fabrication of High Performing and Durable Nickel-Based Catalyst Coated Diaphragms for Alkaline Water Electrolyzers

In this work, a catalyst coated-diaphragm (CCD) for classical alkaline electrolysis was prepared by the blade-coating method, using Raney nickel as HER catalyst and a Zirfon® (AGFA Perl UTP 500) diaphragm. Our best CCD reduced the overvoltage in an alkaline single cell by 270 mV at 300 mA cm−2 compared to the benchmark, mainly due to the higher catalytic activity and surface area of the Raney nickel electrode. The new electrode system also showed a low degradation rate of 22 μA cm−2 h−1 after 1000 h at a cell voltage of 2 V. The gas purity tests showed that the CCD has hydrogen in oxygen contamination well below the lower explosion limit, even at low current densities. Therefore, we propose the use of our novel CCD architecture for atmospheric alkaline electrolyzers, which have a partly separated electrolyte cycl