State-of-the-art and developmental trends in platinum group metal-free cathode catalyst for anion exchange membrane fuel cell (AEMFC)

AEMFC is becoming a prominent technology in portable energy sources. In an attempt to make it economical, non-platinum catalysts are necessary to recruit in the application. Numerous researches are accomplished on the development of platinum-free catalysts. This review summarizes the advancements in the synthesis of catalysts consisting of different components and structures. Rotating ring-disk electrode (RRDE) and fuel cell tests are commonly employed to evaluate the activity for oxygen reduction reaction (ORR) and performances of the catalysts. Here, along with the synthesis and characterization data, this information is assembled and analyzed correlating different factors. To the best of our knowledge, 13 among 203 catalysts have overcome the peak power density (PPD) threshold of 1000 mW.cm-2, which belong to the four categories i.e. Metal-Nitrogen-Carbon (M-N-C), Bimetals-Nitrogen-Carbon (MM-N-C), Transition metal oxides (TMO), and non-metallic catalysts (NMC). The improvement in catalyst’s porosity, surface area, conjugation of active sites, and thereby the synthesis procedures have a great effect on the ORR activity and fuel cell performance. In addition to catalyst properties, there are several other significant factors involved such as water management, properties of anion-exchange membrane (AEM) and anion-exchange ionomer (AEI), optimized operating conditions, etc. The previously low-performing catalysts with high ORR activity cannot be ignored from the top-tier catalysts, since enormous improvements are accomplished in membrane conductivity and water management recently.