Corrosion Resistant Supports
Corrosion Resistant Electrocatalyst Supports
We have developed a new class of high-surface-area, mixed-metal-oxide electrocatalyst supports that are corrosion resistant even under the harshest automotive drive cycles. These supports successfully obviate the issue of carbon support corrosion in automotive fuel cells.
“Self-Anchored platinum-decorated antimony-doped-tin-oxide as a durable oxygen reduction electrocatalyst”, C. He, A. Ells, S. Sankarasubramanian, J. Parrondo, C. Gumeci, M. Kodali, I. Matanovic, A. K. Yadav, K. Bhattacharyya, N. Dale, P. Atanassov, & V. Ramani, ACS Catalysis, 11, pp. 7006-7017, (2021).
“Pt supported on titanium-ruthenium oxide is a remarkably stable electrocatalyst for hydrogen fuel cell vehicles”, J. Parrondo, T. Han, E. Niangar, C. Wang, N. Dale, K. Adjemian, & V. Ramani, Proceedings of the National Academy of Sciences, 111(1), pp. 45-50, (2014).
We have investigated and identified transition-metal-oxide (perovskites and pyrochlores) catalysts that exhibit remarkable bifunctional activity for the oxygen evolution and reduction reactions and the hydrogen evolution and oxidation reactions in alkaline media. This catalyst has advanced the state-of-the-art of alkaline electrolyzers for hydrogen production and has revived the concept of a unitized regenerative fuel cell for energy storage/conversion.
“High performance AEM unitized regenerative fuel cell using Pt-pyrochlore as bifunctional oxygen electrocatalyst”, P. Gayen, S. Saha, X. Liu, K. Sharma, & V. Ramani, Proceedings of the National Academy of Sciences, 118(40), (2021).
“Bidirectional energy & fuel production using RTO-supported-Pt–IrO 2 loaded fixed polarity unitized regenerative fuel cells”, P. Gayen, X. Liu, C. He, S. Saha, & V. Ramani, Sustainable Energy & Fuels, 5, pp. 2734-2746, (2021).
“Pt/C/Ni (OH) 2 bi-functional electrocatalyst for enhanced hydrogen evolution reaction activity under alkaline conditions”, G. Wang, J. Parrondo, C. He, Y. Li, & V. Ramani, Journal of The Electrochemical Society, 164(13), pp. F1307-F1315, (2017).
PGM Free Catalysts
PGM Free Catalysts
There is tremendous interest in electrocatalysts devoid of expensive platinum-group-metals. Our group has worked in collaboration with partners to identify outstanding metal-nitrogen-carbon clusters that exhibit high activity for the oxygen reduction reaction. We have also identified non-carbon equivalents that are corrosion-resistant while providing the requisite activity and selectivity.
“Tantalum/titanium oxide nanoparticles as radical scavengers for durable platinum-group-metal-free oxygen reduction catalysts”, H. Xie, X. Xie, G. Hu, V. Prabhakaran, S. Saha, L. Gonzalez-Lopez, A. Phakatkar, M. Hong, M. Wu, R. Shahbazian-Yassar, V. Ramani, M. I. Al-Sheikhly, D. Jiang, Y. Shao, & L. Hu, Nature Energy, January 2022 (Accepted).
“Metal-nitrogen-carbon cluster decorated titanium carbide is a durable and inexpensive oxygen reduction electrocatalyst”, S. B. Cho, C. He, A. S. Thind, S. Sankarasubramanian , J. Parrondo, J. A. Hachtel, A. Y. Borisevich, J-C. Idrobo, V. Ramani, & R. Mishra, ChemSusChem 14, pp. 4680-4689, (2021), (Front Cover Invitation).
“High-performance single atom Co-N-C catalyst for proton exchange membrane fuel cells: Activity improvement and degradation mechanism identification”, X. Xie, C. He, B. Li, Y. He, D. A. Cullen, E. C. Wegener, A. J. Kropf, U. Martinez, Y. Cheng, M. H. Engelhard, M. Bowden, M. Song, T. Lemmon, X. Li, Z.Nie, J. Liu, D. J. Myers, P. Zelenay, G. Wang, G. Wu, V. Ramani, & Y. Shao, Nature Catalysis, 3(12), pp. 1044-1054, (2020).
We have investigated and identified pyrochlore-based catalysts that exhibit remarkable activity for the oxygen evolution reaction in alkaline media, with one material, lead-ruthenate pyrochlore, being by far the best material available today. This catalyst also exhibits bifunctional activity for the oxygen evolution and reduction reactions in alkaline media and has advanced the state-of-the-art of alkaline electrolyzers for hydrogen production.
“Pyrochlore electrocatalysts for efficient alkaline water electrolysis”, J. Parrondo, M. George, C. Capuano, K. E. Ayers, & V. Ramani, J. Mater. Chem. A, 3, pp. 10819-10828, (2015).
The activity and the selectivity of the oxygen evolution reaction (OER) and chlorine evolution reaction (CER) vary with the facets of a catalyst. We identified the selectivity descriptor which will guide us in identifying the most OER-selective and the CER-selective facet in RuO2 catalyst. The understanding of facet dependent CER selectivity in RuO2 can be extended as a design strategy to modulate OER and CER selectivity in other catalyst as well.
“Facet-dependent Chlorine and Oxygen Evolution Selectivity on RuO2: An Ab initio Atomistic Thermodynamic Study”, S. Saha, P. Gayen, & V. K. Ramani, ChemCatChem, 12, pp. 4922–4929, (2020).