Abstract

A sustainable society requires advanced catalysis technology to achieve efficient green production and energy conversion. Oxygen reduction reaction (ORR), an important half-cell reaction in fuel cells as well as a portable method to produce hydrogen peroxide (H2O2), has attracted wide attention. However, in the transportation sector, prototypical vehicles powered by fuel cells have shown limited progress in technology maturation and adoption over the years. Meanwhile, decentralized electrochemical production of H2O2 currently restricted by poor selectivity and low efficiency. The bottleneck of fuel cells commercialization and H2O2 production likely stems from the kinetic and selectivity issues of ORR.1, 2 Inspired by laccase, a natural, efficient ORR catalyst,3 different metal complexes, such as CuDAT,4 were investigated for catalyzing both 2-electron and 4-electron pathways of ORR. Subsequently, their electrochemical performances were enhanced by pulsed laser treatment. 

Here, I focus on ORR product selectivity tuning by different metal complexes as well as catalytic performance improvement by pulsed laser treatment. Based on the current experimental data, the laser-treated Cu complex of 3, 5-diamino-1, 2, 4-triazole (CuDAT) undergoes a more complete 4-electron reduction than the original CuDAT, while Fe complex of benzene-1,3,5-tricarboxylate (FeBTC) produces more H2O2 after pulsed laser treatment. These interesting results indicate that pulsed laser treatment affects catalytic performances of complexes, and the selectivity bias is related to the ligand architecture and metal center. Further investigation will be conducted to optimize the pulsed laser treatment parameters as well as examine other ligand frameworks and transition metals to achieve a durable and scalable ORR catalyst with high efficiency and predictable selectivity.

Reference:

1. Gewirth, A.A. and Thorum, M.S., Electroreduction of dioxygen for fuel-cell applications: materials and challenges. Inorg Chem, 2010. 49(8): p. 3557-66.
2. Shao, M., Chang, Q., Dodelet, J.P., and Chenitz, R., Recent Advances in Electrocatalysts for Oxygen Reduction Reaction. Chem Rev, 2016. 116(6): p. 3594-657.
3. Mano, N., Soukharev, V., and Heller, A., A laccase-wiring redox hydrogel for efficient catalysis of O2 electroreduction. J Phys Chem B, 2006. 110(23): p. 11180-7.
4. Thorum, M.S., Yadav, J., and Gewirth, A.A., Oxygen reduction activity of a copper complex of 3,5-diamino-1,2,4-triazole supported on carbon black. Angew Chem Int Ed Engl, 2009. 48(1): p. 165-7.