Noble Metal Based Electrocatalysts for Alcohol Oxidation Reactions in Alkaline Media

Alkaline direct alcohol fuel cells (ADAFCs) represent an attractive alternative to hydrogen fuel cells for the more convenient storage, transportation, and lower cost of alcohols (e.g., methanol and ethanol) when compared with compressed hydrogen. However, the anode alcohol oxidation reaction (AOR) is generally plagued with high overpotential and sluggish kinetics, and often requires noble metal-based electrocatalysts to accelerate the reaction kinetics. To this end, the development of efficient AOR electrocatalysts with high mass activity (MA), high durability, high Faradaic efficiency (FE), and low overpotential is central for realizing practical ADAFCs. Here, in this minireview, a brief introduction of the fundamental challenges associated with AOR in alkaline electrolyte, the key performance metrics, and the evaluation protocols for benchmarking AOR electrocatalysts are presented, followed by a summary of the recent advances in the noble-metal based AOR electrocatalysts (e.g., Pt, Pd, and Rh) with an emphasis on the design criteria for improving the specific activity and electrochemical surface area to ultimately deliver high MA while at the same time ensuring long term durability. The strategies to enhance FE and lower overpotential will also be discussed. Last, it is concluded with a brief perspective on the key challenges and future opportunities.