(6ge) Engineering Redox-Active Materials from Electrocatalysis to Pseudocapacitance

Redox-active materials represent the most promising prospect towards electrocatalytic systems and energy storage technologies. However, the poor understanding of redox chemistry at the molecular level limits the activity improvement and further industrial application.

I will first describe our research efforts on the synthesis of high valued chemicals and fuels from renewable electricity and CO₂ [1-5]. We focus on developing, understanding, and eventually designing new catalysts for electroreduction of CO₂ and water oxidation reaction using computational materials science, in situ/ex situ synchrotron X-ray spectroscopies, and advances in materials chemistry. Specifically, I will report a concept to engineering the redox chemistry by introducing isolated single sites and incorporating the third element to modulate the active species. Next, I will discuss the molecular insights to engineer the redox reactions for pseudocapacitance [6]. We change the dominant charge storage mechanism from surface redox reactions to ion intercalation into bulk material by atomic-level structure engineering of metal oxides.

1. Zheng X, Tang J, Ji Y, Wang J, Liu B, Steinrück H, Lim, K, Li Y, Toney M, Chan K, Cui Y, Theory-guided discovery of Cu-Sn alloys with high formate selectivity at low overpotentials, Nature Catalysis, 2019, 2, 55-61.
2. Zheng X, Zhang B, Sargent E H, et al. Theory-driven design of high-valence metal sites for water oxidation confirmed using in situ soft X-ray absorption. Nature Chemistry, 2018, 10, 149-154. (IF=27.9).
3. Zheng X, De Luna P, Sargent E H, et al. Sulfur-modulated tin sites enable highly selective electrochemical reduction of CO₂ to formate, Joule, 2017, 1, 794-805. (Featured article, Cell Press)
4. Zhang B*, Zheng X*, Voznyy O*, Sargent E H, et al. Homogeneously dispersed multimetal oxygen-evolving catalysts. Science, 2016, 352(6283): 333-337 (* co-first author). (IF=33.6)
5. Zheng X, Song J P, Ling T, et al. Strongly coupled nafion molecules and ordered porous CdS networks for enhanced visible‐light photoelectrochemical hydrogen evolution. Advanced Materials, 2016, 28, 4935-4942. (Cover, IF=18.96)
6. Ling T*, Da P*, Zheng X*, Ge B*, Hu Z, Wu M, Du X, Hu W, Jaroniec M, Qiao S, Atomic-level structure engineering of metal oxides for high-rate oxygen intercalation pseudocapacitance, Science Advances, 2018, 4, eaau6261.

Teaching Interests:

I would be very interested in teaching a course on Sustainable Energy and Catalysis, including fuel cells, batteries, photocatalysis, carbon dioxide reduction, N₂ reduction etc. This course could be offered to both undergraduate and graduate students, and provide learning for students in the important area of sustainable energy. I would be very happy to work with my colleagues and teach a course on Advanced X-ray Techniques for Materials and Chemistry. The unique properties of synchrotron radiation, including continuous spectrum, high flux and brightness, and high coherence, provide unprecedented experimental tools to study materials science, bioscience, geoscience, physical and chemical sciences, among many others. The goal of the course is to get students familiar with the advanced X-ray techniques for their research in chemical engineering, materials science, chemistry, physics, etc. The course will consist of fundamentals of interaction between X-ray and matter, X-ray sources, spectroscopy, scattering, imaging, and software learning. This course could be offered to students of graduate students’ levels.