Solvent-Engineering of High-Performance Non-Precious Metal Catalysts

Non-precious metal catalysts (NPMCs) with high volumetric activity and low H₂O₂ yield are being considered as potential replacement for Pt-based oxygen reduction reaction (ORR) catalysts in the PEFC cathode. State-of-the-art NPMCs are typically synthesized from highly heterogeneous precursors and amorphous carbon materials [1-2], which complicate the understanding and development of new materials with improved activities. Recent efforts have been focused on developing carbon nanostructures with superior structural and functional properties from less complex systems, such as graphene oxide (GO). Catalysts derived from GO are more homogeneous and possess several highly desirable properties, such as good chemical stability and excellent conductivity. More importantly, they can be functionalized in a controlled manner [3]. Our efforts have demonstrated the importance of the effective removal of intercalated water on the structure, and consequently, the ORR activity of GO-based NPMCs [4].

In this study, we report the synthesis of solvent-engineered NPMCs with improved performance based on our findings from the more homogenous GO-based systems (Fig. 1). Despite the widely known presence of residual water in GO and more complex carbon systems, no report exists about the effective removal of water to improve the catalyst activity. In this presentation, we focus on the effect of solvent-engineered pretreatments on the structure and function of the ORR catalysts.

References

1. Wu, G., More, K. L., Johnston, C. M., Zelenay, P., Science, 332, 443-447 (2011).
2. Bashyam, R., Zelenay, P., Nature, 443, 63-66 (2006).
3. Qu, L., Liu, Y., Baek, J.-B., Dai, L., ACS Nano, 4, 1321-1326 (2010).
4. Gupta, G et al, Highly Tunable and Ordered Graphene-Oxide-Based Materials for Energy Applications, 2014 ECS and SMEQ Joint International Meeting (October, 2014).