Prof. Chang-feng Yan
Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, China
Title: Multiscale 3D-ordered anode catalyst layer for high-performance and low-cost PEM water electrolysis
Abstract:
Lowering Iridium loading and promoting performance under high operating current density is crucial to the application of Proton exchange membrane (PEM) water electrolysis. To address it, besides developing highly active electrocatalyst, the construction of adequate triple-phase boundary and facile pathways for electron, proton, mass transport are key to ensure activity expression of membrane electrode assembly (MEA). MEA with 3D ordered catalyst layer is an ideal solution to fulfil both requirements simultaneously, however, the mechanism of performance optimization through structural parameter regulation is unclear.
Herein, with template-assisted controlled electrodeposition, ordered IrOx nanotube arrays with tunable morphology have been developed as simplified model catalyst layer with vertical-aligned pores. Our results show that, when high aspect-ration is applied, the activity expression of catalytic surface is limited, which is mainly due to the restriction of mass transfer. Furthermore, to achieve the balance of active surface area and mass transfer, inner-particle nanopores has been introduced through leaching out of sacrificed metal. The construction of hydrophilic nanopores can also significantly promote the apparent wettability of MEA. Excellent single cell performance of 1.666 V@1.0 A/cm2 and 1.787 @2.0 A/cm2 under 80℃ is achieved with N117 membrane and Ir loading of 0.5 mg/cm2. Overpotential breakdown shows that the mass transport overpotential is negligible. And stable operation under 1.5 A/cm2 for 700 h without decay has been achieved, showing great potential of ordered hierarchical pore structure on the application of PEM water electrolyser under high current density.
Biography: