Activation methods and underlying performance boosting mechanisms within fuel cell catalyst layer

Proton exchange membrane fuel cells (PEMFCs) have been widely acknowledged as a significant advancement in achieving sustainable energy conversion. However, the activation of newly established Pt-ionomer interfaces in the catalyst layer of PEMFCs can be a time-consuming and costly process to ensure proper coupling and performance. In order to gain valuable insights into this crucial activation process, we have conducted a comprehensive analysis and comparison of the commonly employed on-line (such as current or voltage control activation, short-circuiting activation, and air interruption activation) and off-line (including boiling or steaming, acid-treatment, and ultrasonic-treatment) activation methods. Our findings shed light on the underlying mechanisms that contribute to enhanced performance within the catalyst layer, such as the reduction of Pt oxides and hydroxides, improved proton transport, and the reduction of "dead" regions. Moreover, this review emphasizes the significant challenges and future opportunities that lie in further enhancing the performance within the catalyst layer through the activation process.