Facile Sprayed and Electro-Activated Ultra-Low Pt Loading Catalyst for Hydrogen Evolution Reaction and PEM Water...

Polymer electrolyte membrane water electrolysis (PEMWE) is a promising route for high-purity green hydrogen, yet its large-scale deployment is limited by heavy platinum-group-metal (PGM) usage and the high Pt loading required at the cathode. Although methods such as sputtering, atomic layer deposition, and electrodeposition have been explored, they often lead to poor dispersion, non-uniform growth, or agglomeration that reduces catalyst utilization. Achieving high hydrogen evolution reaction (HER) performance at ultra-low Pt loadings, therefore, requires a fabrication strategy capable of producing well-dispersed nanoscale Pt within a thin, mass-transport-efficient catalyst layer. Herein, we introduce a spray-coating assisted electrochemical reduction (Pt-SE) method that forms well-dispersed 2-3 nm Pt nanoparticles at an ultra-low loading of 0.0178 mg_Pt cm^-2. Pt-SE delivers excellent HER activity, including an overpotential of 87 mV at 1 A cm^-2 and a mass activity of 34.4 A mg_Pt ^-1, exceeding commercial Pt/C by more than 30-fold. As a PEMWE cathode, Pt-SE achieves 1.62 V and 90.6% higher-heating-value efficiency at 1 A cm^-2. Further, techno-economic analysis shows that the 98% reduction in Pt usage lowers the levelized cost of hydrogen to 3.91$ kg_H2 ^-1, within the DOE 2030 target range. These results highlight Pt-SE as a scalable and economically compelling approach for ultra-low-PGM PEMWE systems.