Carbonaceous Supported Pt-Alloy Based Nanocomposite Electrocatalysts for Methanol Electrooxidation Reaction in Direct Methanol Fuel Cell: A Review

The DMFC commercialization and practical operations are still confronts several major challenges particularly in high cost, maintaining long-term stability and durability, deteriorating of anode electrocatalyst performance as well as the sluggish methanol oxidation kinetic reaction occurred at the anode due to the poisoning effect of the platinum (Pt) electrocatalyst. The selection of the appropriate anode electrocatalysts for methanol oxidation reaction (MOR) is quite limited, only the anode electrocatalysts that can enhance the MOR activity and minimize the poisoning effect by the carbonaceous intermediate species-like carbon monoxide (CO) can be considered to improve the DMFC performance. The strategy of coupling or alloying Pt with other noble or non-noble metals can prevent such mentioned problems above and able to upgrade the ability of anti-CO poisoning through the modification of the CO adsorption site. In general, the highly accessible of electrocatalytic active sites and dispersed are very important for the superior Pt-based alloy electrocatalyst performance through the utilization of the electrocatalyst support with the large specific surface areas. However, the commonly used carbon supporting materials for monometallic Pt and bimetallic Pt-based alloy electrocatalysts suffer from severe corrosion due to the electrooxidation on the surface under acidic condition at high operating voltages for prolonged times which resulting the dissolution, aggregation, migration and detachment of Pt NPs leading to a serious problem of stability. The most efficient strategy to overcome the limitations described above is through the embedding the monometallic Pt and bimetallic Pt-based alloy electrocatalyst on the metal oxides. This proposed strategy provides a medium to anchor the Pt-based alloy electrocatalyst securely onto the carbonaceous support materials and the electrocatalytic performance of the electrocatalyst also have been proven to be significantly improved in oxidizing the methanol in DMFC. Nevertheless, studies on the possible combination of both supported Pt-based alloy electrocatalyst embedding metal oxides as the potential anode nanocomposite electrocatalyst with careful design still lacking and remains important challenge.