THE PROJECT OBJECTIVE IS TO DEVELOP ULTRA-LOW IR LOADING AND ULTRA-DURABLE OXYGEN EVOLUTION REACTION (OER) POWDER CATALYSTS FOR PROTON EXCHANGE MEMBRANE (PEM) WATER ELECTROLYZERS WHICH DEMONSTRATE EFFICIENCY AND DURABILITY MEETING OR EXCEEDING THE DOE TARGETS. THE OER POWDER CATALYSTS WILL BE INTEGRATED INTO OPTIMIZED HALF-CELL ARCHITECTURES DEFINED BY AN ELECTRODE, POROUS TRANSPORT LAYER (PTL), AND FLOW FIELD (FF), AND EVALUATED IN A FULL CELL ASSEMBLY OF 25CM2 ACTIVE AREA OR LARGER. THE EXPECTED OUTCOME IS ONE OR MORE ELECTROCATALYSTS VALIDATED TO REDUCE THE AMOUNT OF IR NEEDED TO MEET DEVICE EFFICIENCY AND LIFETIME REQUIREMENTS BY CA. 64X (ON A/MG BASIS) OVER CURRENT COMMERCIAL TECHNOLOGY.