(419a) Design of Ni-Based Alloys to Improve Electrocatalytic Performance and Sulfur Poisoning Resistance in Solid Oxide Electrochemical Cells

Due to oil demand growth and global warming, solid oxide fuel cells (SOFCs) have emerged as a new energy conversion system with high electrical efficiency. SOFCs provide excellent fuel flexibility and can operate on fuels such as natural gas and hydrogen. In addition, SOFCs can be operated in a reversed mode as a solid oxide electrolyzer cells (SOECs), which offer the highly efficient hydrogen production and syngas through CO₂ and H₂O co-electrolysis using thermal energy and electricity. Most previous studies of electrodes for SOCs have focused on nickel-yttria stabilized zirconia (Ni/YSZ) cermet because of its high electrical conductivity and low cost. However, Ni/YSZ has several issues to overcome for achieving high performance, such as low activity for CO₂ reduction and low tolerance for sulfur poisoning. Therefore, the comprehensive studies are neccessary to improve electrocatalytic activity and poisoning resistance of the electrodes.

In this study, based on density functional theory calculations, we investigated a series of reactions on a wide range of transition metals to evaluate their ability to increase the performance of conventional Ni catalysts. We could successfully suggest good candidates of Ni-based bimetallic alloy catalysts with excellent activities [1] and sulfur poisoning resistance [2, 3]. Our result will provide insight into improving the electrode catalysts used in the high-temperature fuel cells and electrolysers.

References

[1] A. Cho†, J. Ko†, B-K. Kim, and J. W. Han*, Electrocatalysts with Increased Activity for Coelectrolysis of Steam and Carbon Dioxide in Solid Oxide Electrolyzer Cells, ACS Catal. 9 (2019) 967-976.

[2] B. Hwang†, H. Kwon†, J. Ko, B-K. Kim, and J. W. Han*, Density functional theory study for the enhanced sulfur tolerance of Ni catalysts by surface alloying, Appl. Surf. Sci. 429 (2018) 87-94.

[3] A. Cho†, B. Hwang†, H. Kwon, B-K. Kim, and J. W. Han*, A DFT Study of H₂S Dissociation Reaction on Ni/YSZ and Ni(211), to be submitted.