ONLINE: Sustainable Energy Seminar Series

media release: Welcome back to a new semester of the Sustainable Energy Seminar Series! We hope you all had a good summer break and are ready to get back into the rhythm of the school year. Due to the uncertainty around COVID-19, this semester we will again be using the Zoom webinar platform for all presentations. You can register for all upcoming webinars in this series at the same time (or pick and choose which ones to register for) using this registration link:

https://uwmadison.zoom.us/webinar/register/6016288767526/WN_lVu9D9Z4QUyBtYlSsn-I9g

Sessions will be recorded and will be shared to this seminar list andposted to the WEI website.

Nov. 8:

"Advanced Semiconductor-Electrocatalyst Systems for Photoelectrochemical Hydrogen and Oxygen Production in Microgravity Environment"

Katharina Brinkert, assistant professor, chemistry, University of Warwick

Abstract:

Efficient artificial photosynthesis systems are currently realized as catalyst- and surface-functionalized photovoltaic tandem and triple junction devices [1,2] enabling photoelectrochemical water oxidation while simultaneously recycling CO2 and generating hydrogen as a solar fuel for storable renewable energy. The successful implementation of an efficient photoelectrochemical (PEC) water splitting cell is not only a highly desirable approach to solving the energy challenge on earth: an effective air revitalization system generating a constant flux of O2 while simultaneously recycling CO2 and providing a sustainable chemical and fuel supply is also essential for the International Space Station and long-term space missions, where a regular resupply from earth is not possible.

We recently demonstrated in a series of drop tower experiments that efficient direct hydrogen production can be realized photoelectrochemically in microgravity environment, providing an alternative route to existing life support technologies for space travel [3]. Current limiting factors such as the absence of macroconvection processes were overcome by controlling the nanotopography of the electrocatalyst using shadow nanosphere lithography (SNL), generating so-called catalytic ‘hot-spots’ on the electrode surface which prevent gas bubble coalescence [3,4]. We found that the J-V characteristics of the half-cell and the overall device efficiency in microgravity environment are significantly affected by alterations in the electrocatalyst nanotopography [5]. By varying the shape and distance of catalytic ‘hot-spots’ on the electrode surface, we can control the gas bubble size upon detachment from the electrode surface as well as the surface wettability for an optimized device performance in microgravity and terrestrial applications.

References

• [1] Young J. L., Steiner M. A., Döscher H., France R. M., Turner J. A., Deutsch T. G. Nat. Energ., 2017, 2. (17028).
• [2] Cheng W. H., Richter M. H., May M. M., Ohlmann J., Lackner D., Dimroth F., Hannappel T., Atwater H. A., Lewerenz H. J. ACS Energy Lett.,  2018, 3, 8, 1795-1800.
• [3] Brinkert K., Richter M. H., Akay Ö., Liedtke J., Gierisig M., Fountaine K. T., Lewerenz H. J. Nat. Commun., 2018, 9 (2527). 
• [4] Patoka P., Giersig M. J. Mater. Chem., 2011, 21, 16783-16796.
• [5] Brinkert K., Richter M. H., Akay Ö., Giersig M., Fountaine K. T., Lewerenz H.-J. Faraday Discuss., 2018, 208, 523-535.