The unprecedented momentum gained by the hydrogen economy in recent years has brought Proton Exchange Membrane Fuel Cells (PEMFC) back into the limelight. Despite their zero-emission status, the high cost and durability issues associated with the commonly used Pt/C (platinum on carbon) catalyst have hindered their widespread commercialization. Graphene-based materials are potential candidates for catalyst support owing to their excellent theoretical properties. However, their usage has been limited by various factors such as bottlenecks involved in large-scale production, lower limiting current density and maintaining optimal functional groups for uniform Pt incorporation without compromising the structural stability of graphene sheets.
On this note, in the first part of the work, we have structurally engineered the conventionally prepared reduced graphene oxide support framework with metal oxide hybrids in such a way that it offers sufficient electron conductivity, corrosion resistance, and better Pt access to the reactants by abating the agglomeration of graphene sheets. A combination of physiochemical and electrochemical studies was carried out to gain critical insights into the role played by the individual counterparts and the importance of optimising the composite ratios in building the synergy between the support materials.
Further, functionalized multilayer graphene with in-situ nitrogen doping was synthesized using a simple, one-step electrochemical process at room temperature to address the bottlenecks involved in graphene production. A uniform Pt deposition ( 2 nm) was obtained using a microwave assisted technique. The study provides insights into the impact of various experimental parameters involved in the preparation of the catalysts and the various surface engineering strategies, such as heteroatom doping and interlayer modifications, which can be employed to ameliorate their performance. Brief insights on the role of various co-supports are also discussed. The catalyst with the optimum Pt to carbon ratio outperformed commercial Pt/C when tested in a PEMFC.
Overall, this work has attempted to address the durability issues in fuel cells by focusing on some of the major limitations of alternative graphene-based supports.