Research in Zhenxing Feng's group focuses on three main directions: (1) Electrochemical energy storage; (2) Catalysts for electrochemical and chemical reactions; (3) Development and application of advanced synchrotron based X-ray techniques for in-situ time-resolved studies.

For electrochemical energy storage, we have been working on lithium-ion batteries to improve the energy density and cycling performance. We also explore novel electrochemical storage systems beyond lithium-ion (such as magnesium batteries, etc.) as alternatives for lithium-ion batteries. For energy conversion systems, we study catalysts using both model systems and real materials to figure out their intrinsic descriptors that govern materials chemical and electrochemical properties with a goal to improve the energy conversion efficiency. As the gas/solid, liquid/solid, and solid/solid interfaces in these energy systems are critical parts where many important reactions take place, we develop and apply advanced synchrotron X-ray techniques, including scattering, spectroscopy, imaging, and pump-probe methods at different national user facilities (e.g., Advanced Photon Source in Argonne National Lab, Advanced Light Source in Lawrence Berkeley National Lab, National Synchrotron Light Source II at Brookhaven National Lab), to understand the interfacial processes during operational conditions. The learned mechanistic insights, in turn, have helped us to further design many energy materials in rational ways. 

Electrochemical Energy Storage

Lithium-ion batteries (LIBs) have been widely used for transportation (e.g., electric vehicles). However, the energy density and cycling life of commercial LIBs are not good enough, which makes them hard to power electric vehicles for more than 300 miles as replacements for gasoline-based cars. We are working on electrode materials by modifying their bulk and surface structures to improve their lithium intercalation capacity and stability in battery operations. 

We also have particular interests on aqueous batteries that uses water-based electrolytes. Aqueous batteries are inherently safer than LIBs that contain flammable organic electrolytes. However, the stable voltage window of aqueous batteries is limited by the water electrolysis voltage (1.23 V), and consequently affects the energy density. We have been working on different strategies (e.g., water-in-salt electrolyte) to expand the voltage window more than 1.23 V in different types of aqueous batteries (e.g., sodium-ion, zinc-ion batteries).

Representative publications

S. Qiu et al., Nano Energy, 64, 103941, 2019. DOI: 10.1016/j.nanoen.2019.103941

L. Ju et al., Advanced Energy Materials, 10, 1903333, 2020. DOI: 10.1002/aenm.201903333

H. Tian et al., Nature Communications, 12, 237, 2021. DOI:10.1038/s41467-020-20334-6. Highlighted by OSU News, ScholarSet, APS User Science Highlight, The Chemical Engineer, KGW Channel 8

Catalysts for Electrochemical and Chemical Reactions

Electrocatalysts are key to improve the efficiency of many electrochemical reactions such as oxygen reduction reaction (ORR) in fuel cells, oxygen evolution reaction (OER) in electrolyzers and electrochemical carbon dioxide reduction reaction (CO2RR). We use sol-gel and solid-state methods to synthesize oxide-based materials and test their activity as well as selectivity. We also use scattering and spectroscopic methods to study electrocatalyts' structural as well as compositional changes in different reactions.  Collaborative works (e.g., atomically dispersed catalysts, high-entropy alloy catalysts) are quite common in my group, too. 

Representative publications

M. Wang et al., ACS Applied Materials & Interfaces, 11, 5682-5686, 2019. DOI: 10.1021/acsami.8b20780

X. Zhang et al., Nature Energy, 5, 684–692, 2020. DOI: 10.1038/s41560-020-0667-9, Highlighted by OSU News.

G. Wan et al., Science Advances, 7, eabc7323, 2021, DOI: 10.1126/sciadv.abc7323. Highlighted by OSU News, ScholarSet, H2Bulletin.

In Situ Real-Time Studies of Interfacial Processes

Advanced characterizations are useful to probe materials' changes in different electrochemical reactions, thus providing insights or feedback for better synthesis, performance improvement and rational design. Synchrotron X-ray techniques, including scattering, spectroscopy and imaging are heavily used in the group to exam materials' structure, chemical states and morphology. In addition to design various in-situ and operando reaction cells, students in the group visit synchrotron facilties at different national laboratories to X-ray characterizations. We are also working with scientists to develop new tools that can have better temporal and spatial resolution for mechanistic studies.

M. Wang et al., Nano-Micro Letters, 11, 47, 2019, DOI: 10.1007/s40820-019-0277-x.

Z. Feng, Encyclopedia of Energy Storage, 2021. DOI:10.1016/B978-0-12-819723-3.00048-2

J. Deng et al., Review of Scientific Instruments, 90, 083701, 2019. DOI:10.1063/1.5103173. Highlighted by Scilight and featured as the cover