Tuning the In-Plane Electrical Conductivity and Performance of the Low Ir Anode in a Proton Exchange Membrane Water Electrolyzer

In a proton exchange membrane water electrolyzer, directly reducing the Ir loading in the anode always leads to a decline in performance. The limited in-plane electrical conductivity of the inhomogeneous catalyst layer is one of the reasons that constrain the improvement of cell performance. Herein, to enhance the activity of the low Ir anode, continuous gold films with different thicknesses are coated on a conventional IrO2 catalyst layer to form bilayer anodes. The gold film acts as a bridge for connecting isolated IrO2 agglomerates, thus endowing an improved in-plane conductivity and Ir mass activity. A significant improvement of cell performance is observed with the bilayer anode, and the overpotential breakdown analysis further interprets the origin of the performance enhancement. Moreover, an electrochemical imaging technique by using the ex situ scanning vibrating electrode technique is adopted for the direct observation of the active area distribution of the electrode, and the mechanism that how in-plane conductivity affects the Ir utilization is elucidated.