MSE Colloquium: Ke Sun, Materials and Systems at Nanoscale for Carbon-free Energy Future

Breaking our fossil fuel habit in one step

Abstract

Extensive use of fossil fuels to support the growth of economy and population causes serious impacts to the environment, damage to public health, habitat loss, and climate change. Efficiently harvesting renewable energies like solar and wind is capable to meet our energy demand with a minimized environmental impact. However, storing intermittent renewable energies based on current battery technologies is either extremely expensive or has low energy density to scale up. Solar energy conversion and its direct storage in chemical fuels (solar fuel) using only water and air have received recent attentions worldwide, which could fully unlock the potential of solar energy and deep decarbonize our energy system by providing a grid-level storage of solar energy. Chemical fuels produced from this technology can be stored and transported through existing infrastructures, e.g., gas tanks and pipelines. Fuels then can be directly used in gas turbines for centralized power plants, internal combustion engines for heavy-duty vehicles that cannot be electrified, and fuel cells for energy generation in isolated areas.

In artificial photosynthesis based on semiconductor photoelectrochemistry, the production of chemical fuels generally requires the coupling of semiconductors with electrocatalysts where electrical charges are generated, separated and transferred for multi-electron chemical reactions, as well as the pairing of light-absorbing materials with optimum bandgap combinations. The development of such proof-of-concept systems has been hindered in part by the lack of semiconducting materials that can provide low-cost, efficiency and stability simultaneously in a corrosive environment, typically either strong acid or base.  In this talk, I will present our recent progress in the development of stable and efficient solar fuel systems for sustainable H2 generation from splitting water and formate production from CO2 reduction. I will then introduce the concept of artificial N2 photo-fixation for sustainable NH3 production, a promising candidate for carbon-free energy future. Finally, I will review the state-of-the-art, highlight the grand challenges/impact, and overview the proposed research program to tackle this problem in my future group.

Bio

Dr. Ke Sun is currently a senior postdoctoral fellow advised by Professor Nathan Lewis in the Division of Chemistry and Chemical Engineering and the Joint Center for Artificial Photosynthesis (JCAP) at Cal Tech. His research during the past 3 years in solar fuel from only water and air pursues the development of solutions to fill the knowledge gap in realizing an efficient and stable solar-to-fuel conversion through a rational management of photons, electrons and ions in the coupled photo-electro-chemical process. To advance the nanoscale characterization and develop understandings of the corrosion/passivation/degradation process on photoelectrodes while in-action, he has recently begun to develop platforms to integrate state-of-the-art microscopic/spectroscopic techniques with in-situ electrochemical measurement. He obtained his Ph.D degree from the University of California, San Diego in 2013 in Prof. Deli Wang’s group at the Department of Electrical and Computer Engineering. His graduate work involved the synthesis and integration of quantum confined nanostructures of III-V compound materials, silicon, metal and dielectrics using chemical vapor deposition, metal organic vapor deposition, molecular beam epitaxy, dry etching, patterned electrodeposition, and hydrothermal growth, and their applications in biosensors, artificial retina, photovoltaics, optoelectronics, transistors, and solar fuel devices.

Dr. Sun has published 37 publications in Chem. Rev., PNAS, JACS, Energy Env. Sci., Nano Letters, ACS Nano, and etc. A lot of his work has been featured by the U.S. Department of Energy, Nature Energy, MIT Technology Review, Discovery and etc. He has 4 ESI highly cited papers in Physics and Chemistry and has been cited for >1150 times. He has presented 11 invited talks in conferences and 12 invited seminars at universities and companies. He also holds 2 patents and several university disclosures.