An Overview of the Pd Based Electrocatalysts Utilized in Direct Alcohol Fuel Cells

It is well known that direct alcohol fuel cells (DAFCs) are ideal power sources for portable equipment and electric vehicles, due to the advantages of alcohol, such as renewability, safety, high energy density and ease of storage and transportation. However, their applications are limited by the scarce resources and poor operational durability of commercial Pt-based cata-lysts. Consequently, numerous alternative catalysts have been reported over the past decades, including MOF (Metal–Organic Framework) materials, M–N-C (M = transition metal atom) single-atom catalysts, Pd-based catalysts and others. Among these, Pd-based catalysts exhibit high electro-activity for both alcohol electro-oxidations and oxygen reduction reactions, particularly for ethanol electro-oxidation. Significant efforts have been made to enhance the activity and durability of Pd-based catalysts for use in DAFCs. Despite these efforts, commercialization is progressing slowly. Therefore, advancing the commercial application of DAFCs has become a pressing issue for both enterprises and researchers. Exploring novel Pd-based catalysts with exceptionally high activity and stability is likely to address this challenge. This review summarizes the classifications, synthesis methods, current research status and prospects of Pd-based catalysts to provide effective research directions and methods for improving their investigation.