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

A catalyst coated-diaphragm (CCD) for classical alkaline electrolysis was prepared by the blade-coating method, using Raney nickel as hydrogen evolution reaction 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 cycle.