2017 Grand Prize Winners
Wen-Hui (Sophia) Cheng and Matthias H. Richter
Breakthrough Efficiency of Direct Water Splitting with Monolithic Photoelectrochemical Device in Sustainable Operating Conditions
Wen-Hui Cheng is a PhD student in Materials Science. She is member of Professor Harry Atwater’s research group and part of the Joint Center of Artificial Photosynthesis (JCAP). Matthias Richter is a postdoctoral scholar in Professor Nate Lewis’ group, also working with JCAP. Their winning innovation is a breakthrough device for splitting water with sunlight to make hydrogen fuel with remarkable efficiency!
The team’s promising design brings us closer to meeting the US Department of Energy’s target of $2/kg hydrogen and paves the way for high performance to become the new norm. By carefully managing the electronic properties of the semiconductor/protection layer/catalyst combination, the anti-reflection properties of the protection layer, and optical properties of the high performance catalyst used for hydrogen production, their device works with record solar-to-hydrogen efficiency of 18.5%.
Using a tandem III-V photovoltaic structure in conjunction with optimized electrocatalysts that are deposited by methods they developed, their device maximizes the efficiency, while minimizing parasitic optical absorption and reflection losses. Operating at approximately 80% of the theoretical maximum for the light absorbers used, their results signify that catalyst overpotentials are minimized, resistive losses through the device are lessened, and optical losses are largely reduced.
The team’s future work will begin to explore the advantages of having a device that works well at neutral pH. Chief among these is the electrochemical reduction CO2 to potential carbon-based fuels or fuel precursors, as this process is generally best accomplished at neutral pH. Transforming waste CO2 by direct photoelectrochemical CO2 reduction into a valuable raw material is an important first step towards a circular CO2 economy and CO2 footprint mitigation.