Nanoporous Nickel Phosphide Cathode for a High-Performance Proton Exchange Membrane Water Electrolyzer

Hydrogen production via a proton exchange membrane water electrolyzer (PEMWE) is an essential technology to complement discontinuity of renewable energies. Development of a high-efficiency and cost-effective gas diffusion electrode (GDE), which is a key component of this technology, remains a challenge. Here, we report a high-performance Ni phosphide GDE prepared by simple electrochemical methods. Selective leaching of excess Ni in electrodeposited NiP_1- enabled fabrication of a nanoporous NiP GDE with a large electrochemical surface area (ECSA). In half-cell tests, the nanoporous NiP GDE demonstrated a hydrogen-evolving current density of -10 mA/cm² at an overpotential of 103 mV with good stability. In the single-cell tests, the PEMWE employing a nanoporous NiP cathode exhibited a current density of 1.47 A/cm² at a cell voltage of 2.0 V, which was the competitive performance among state-of-the-art non-noble cathodes reported to date.