NSTF Advances for PEM Electrolysis - the Effect of Alloying on Activity of NSTF Electrolyzer Catalysts and Performance of NSTF Based PEM Electrolyzers

Abstract

Current interest in developing environmentally sound methods of energy generation and storage has led to a renewed interest in hydrogen generation via polymer electrolyte membrane (PEM) electrolysis. PEM electrolysis could provide a clean alternative to existing hydrogen production methods, such as steam reforming, if both the capitalization and operational expenses can be properly managed to improve its economic benefits as well as its environmental benefit.In this paper we explore one method of reducing the capital expenses by both lowering the amount of PGMs used to operate a PEM electrolyzer, and increasing the operating power level per cell. We start off by using 3M’s nano-structured thin film (NSTF) support to reduce the total mass required compared to conventional dispersed catalysts on both the anode and cathode, with exceptional success. Not only is such a NSTF electrolyzer able to operate with only 0.25 mg _Ir·cm ^-2 on the anode, in addition to 0.25 mg _Pt·cm ^-2 on the cathode, the maximum current density we can obtain with this setup approaches 20 A·cm ^-2. In an attempt to improve the electrode conductivity and lower Ohmic losses over standard iridium oxide, we continued by testing iridium-platinum alloys in both conventional single cell electrolyzer tests and rotating disk electrode tests. Unfortunately, it appears Pt drastically inhibits the OER on the resulting Ir _xPt _y-NSTF alloy catalyst.