(6dq) Advanced Materials for Efficient Energy Conversion Based on Spectroscopic and Mechanistic Study

Developing catalytic materials and device to enable efficient interconversion of chemical and electrical energies, e.g., fuel cells and electrolyzers, is key to sustainable future. Despite the explosive growth of new materials, few has demonstrated satisfactory performance under realistic conditions in an MEA configuration. Guiding principles in rational design of electrocatalysts remain elusive. Developing advanced materials with enhanced catalytic performance, as well as manipulation of the interfaces between catalysts and membrane, is key to enable efficient energy conversion under realistic conditions in an MEA configuration. Through spectroscopic and fundamental mechanistic studies, the reaction pathway on catalysts can be monitored in MEA configuration, which provides insights for the rational design of nanostructured materials with well-defined structure/composition and manipulation of MEA interfaces to achieve high performance.

Research Interests:

Developing catalytic materials and device to enable efficient interconversion of chemical and electrical energies, e.g., fuel cells and electrolyzers, is key to sustainable future. Guiding principles in rational design of electrocatalysts remain elusive. Despite the explosive growth of new materials, few has demonstrated satisfactory performance under realistic conditions in an MEA configuration. Developing advanced materials with enhanced catalytic performance, as well as manipulation of the interfaces between catalysts and membrane, is key to enable efficient energy conversion under realistic conditions in an MEA configuration.

In my PhD research, with Prof. Erkang Wang at Changchun Institute of Applied Chemistry, I developed a selective, active, and stable catalyst for oxygen reduction reaction (ORR), whose sluggish kinetics hinders the commercialization of fuel cells. By decreasing the size of silver nanoparticles to < 2 nm (2 to 5 atoms), the utilization efficiency of catalyst atoms was improved significantly, leading to superior performance as compared to the commercial Pt/C. During my postdoctoral research with Prof. Younan Xia at Georgia Institute of Technology, I developed a type of cost-effective Pt nanocages for ORR with enhanced catalytic activity and durability. Owing to the unique architectures of the synthesized nanoparticles, such as hollow interiors, porous walls, and well-defined facets, the Pt utilization efficiency and specific activity of Pt nanocages were significantly enhanced. During my postdoctoral research with Prof. Bingjun Xu and Prof. Yushan Yan at the University of Delaware, I successfully developed catalysts for electrochemical nitrogen reduction reaction (ENRR) by evaluating them under realistic conditions in an MEA configuration. Further, I have also developed expertise in operando surface enhanced infrared absorption spectroscopy (SEIRAS) to quantify the surface pH changes within the electrochemical double layer using CO₂ reduction reaction as a model system.

In my future research, I plan to develop advanced materials for efficient energy conversion including fuel cell and electrolysis by taking advantage of my unique background in material science, electrolysis, and spectroscopy. Through spectroscopic and fundamental mechanistic studies, the reaction pathway on catalysts can be monitored in MEA configuration, which provides insights for the rational design of nanostructured materials with well-defined structure/composition and manipulation of MEA interfaces to achieve high performance. For example, ORR as the cathode reaction has attracted intensive research interests because of its rate-determining role in fuel cells. Numerous nanomaterials have been demonstrated as catalysts for ORR with enhanced activity and durability in rotating disk electrode (RDE) setup. However, few of them show good performance in fuel cells due to the differences between RDE and MEA configurations. Through operando spectroscopic monitoring of ORR in both RDE and MEA configurations, the interfaces between catalysts and ionomer/membrane can be manipulated, which enables the discovery of advanced materials with enhanced catalytic performance in MEA. With extensive experience in the synthesis of nanomaterials and strong expertise in MEA and operando SEIRAS, I am uniquely suited to undertake these challenging research efforts.

Teaching Interests:

I have extensive experience working with undergraduate and graduate students during my stay at Georgia Institute of Technology and the University of Delaware, and enjoyed teaching them material syntheses, electrochemical measurements, and SEIRAS. I am interested in teaching most of the core Chemical Engineering courses, including thermodynamics and kinetics. I also plan to develop elective courses close to my research interest such as, spectroscopy, catalysis, material sciences, nanoscale fabrication, and electrochemistry.

Selected Publications:

1. Nash, J.*; Yang, X.*; Anibal, J.; Wang, J.; Yan, Y; Xu, B. Electrochemical Nitrogen Reduction Reaction on Nobel Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers. Journal of the Electrochemical Society 2017, 164, F1712−F1716.
2. Dunwell, M.; Yang, X.; Setzler, B.; Anibal, J.; Yan, Y.; Xu, B. Examination of Near-Electrode Concentration Gradients and Kinetic Impacts on the Electrochemical Reduction of CO2 using Surface-Enhanced Infrared Spectroscopy. ACS Catalysis 2018, 8, 3999−4008.
3. Yang, X.*; Gilroy, K. D.*; Vara, M.; Zhao, M.; Zhou, S.; Xia, Y. Gold icosahedral nanocages: facile synthesis, optical properties, and fragmentation under ultrasonication. Chemical Physics Letters 2017, 683, 613−618.
4. Yang, X.; Roling, L. T.; Vara, M.; Elnabawy, A. O.; Zhao, M.; Hood, Z. D.; Bao, S.; Xia, Y. Synthesis and characterization of Pt−Ag alloy nanocages with enhanced activity and durability towards oxygen reduction. Nano Letters 2016, 16, 6644−6649.
5. Wang, X.; Figueroa-Cosme, L.; Yang, X.; Luo, M.; Liu, J.; Xie, Z.; Xia, Y. Pt-based icosahedral nanocages: Using a combination of {111} facets, twin defects, and ultrathin walls to greatly enhance their activity toward oxygen reduction. Nano Letters 2016, 16, 1467−1471.
6. Yang, X.; Gan, L.; Zhu, C.; Lou, B.; Han, L.; Wang, J.; Wang, E. A dramatic platform for oxygen reduction reaction based on silver nanoclusters. Chemical Communications 2014, 50, 234−
7. Yang, X.*; Gan, L.*; Han, L.; Wang, E.; Wang, J. High-yield synthesis of silver nanoclusters protected by DNA monomers and DFT prediction of their photoluminescence properties. Angewandte Chemie International Edition 2013, 52, 2022−2026.