The Application of Pd-Based Nanomaterials for Methanol Oxidation and Oxygen Reduction Reaction in The Direct Methanol Fuel Cells

Direct methanol fuel cells (DMFC) are considered as a sustainable and environment-benign energy source which provide electrical energy from chemical energy with less pollution, higher efficiency, and noiseless operation. In this review, the application of the Pd-based nanomaterials for the oxygen reduction reaction(ORR) that is carried out on the cathode and the methanol oxidation reaction(MOR)that is carried out on the anode are discussed in the direct methanol fuel cells. At first, the mechanisms of ORR and MOR will be described. Then, the bimetallic and multi-metallic nanomaterials including Au/C-Pd/C, Pd3Sn/CNTs NHs, and Pd3Ag1/meso-CeO2 will be summarized focusing on stability, the catalytic activity and performance for ORR. Furthermore, supports like reduced graphene oxide (rGO) with modified POM, carbide-derived carbon (CDC), and nitrogen-doped graphene quantum dots (NGQD) that Pd nanoparticles (NPs) are deposited on will influence the activity of the catalysts for ORR. The study for the use of Pd/TiO2 decorated carbon fibers for methanol oxidation will also be discussed and the effects of different TiO2 mass fractions on conductivity, EASA value, and electrochemical activity will be summarized.