Synthesis methods of low-Pt-loading electrocatalysts for proton exchange membrane fuel cell systems

While the use of a high level of platinum (Pt) loading in proton exchange membrane fuel cells (PEMFCs) can amplify the trade off towards higher performance and longer lifespan for these PEMFCs, the development of PEMFC electrocatalysts with low-Pt-loadings and high-Pt-utilization is critical and the limited supply and high cost of the Pt used in PEMFC electrocatalysts necessitate a reduction in the Pt level. In order to make such electrocatalysts commercially feasible, cost-effective and innovative, catalyst synthesis methods are needed for Pt loading reduction and performance optimization. Since a Pt-deposited carbon nanotube (CNT) shows higher performance than a commercial Pt-deposited carbon black (CB) with reducing 60% Pt load per electrode area in PEMFCs, use of CNTs in preparing electrocatalysts becomes considerable. This paper reviews the literature on the synthesis methods of carbon-supported Pt electrocatalysts for PEMFC catalyst loading reduction through the improvement of catalyst utilization and activity. The features of electroless deposition (ED) method, deposition on sonochemically treated CNTs, polyol process, electrodeposition method, sputter-deposition technique, γ-irradiation method, microemulsion method, aerosol assisted deposition (AAD) method, Pechini method, supercritical deposition technique, hydrothermal method and colloid method are discussed and characteristics of each one are considered.