This project will focus on photoelectrochemical splitting of water into hydrogen and oxygen. Oxidation of water at the anode surface is a kinetically difficult process, typically requiring overpotentials of several hundred millivolts even on the most efficient catalysts, noble metals such as Ir or Ru and their oxides. The PI will study atomic layer deposition (ALD) for ultra-thin film deposition, nanostructuring and surface alloying to minimize the use of these metals in highly efficient water oxidation catalysts, and to explore more Earth-abundant catalyst alternatives for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both single-junction and tandem photoelectrochemical cells. Well-established in semiconductor device fabrication, ALD is now being investigated for energy applications, enabling high-impact discoveries.
This project would be an international partnership supported jointly by NSF, Science Foundation Ireland, and Invest Northern Ireland through the US-Ireland Research and Development Partnership Program. If supported by NSF, the RENEW project would bring to bear the efforts of four PI?s at three universities (Stanford, Tyndall National Institute/UCC, Queens University Belfast) with complementary expertise. The approach integrates activities at our universities to provide both significant intellectual benefits and unique broader impacts of the research.
The PI will focus on the nanoscale engineering of water oxidation catalysts deposited on ultrathin, ALD-grown tunnel oxide supports. Consistent with the recent work on pinhole-free tunnel oxides for efficient and stable photoelectrochemical water oxidation on silicon, the PI will test if these layers achieve corrosion protection of a variety of Earth-abundant semiconductor absorbers with appropriate band edges for efficient solar-driven water splitting. With ALD as a versatile tool for nanoscale materials design, the goals are to study ultra-thin film and nanoscale island catalysts, and surface-alloying of noble metals in tunnel oxide layers. The latter structures constitute an ultrathin, ALD-grown analogue to the much thicker RuO2-TiO2 dimensionally stable anode coatings used in the electrochemical industry. RENEW team efforts will include screening of Earth-abundant, nanocrystalline OER catalysts by wet chemical synthesis methods and development of ALD processes for their deposition. The PI will also explore II-VI semiconductor absorbers for single-junction and tandem photosynthesis cells with corrosion-resistant photoanodes and cathodes. Possible applications of this research include grid-scale storage of solar energy and solar-driven synthesis of more complex and energy-dense hydrocarbon fuels, for which water oxidation is likely a required step.
Broader impacts of this project would flow from both international personnel exchanges, including extended student researcher-in-residence visits, across the RENEW team universities, and the coupling of energy and materials research with undergraduate science education at Stanford. In one of two joint efforts in education and outreach, the PI plan to collaborate in the development of a freshman-level electrochemistry course module, using electrolysis of water and corrosion protection of metals as examples of practical applications of electrochemistry. The module will be available for free download from the internet and will include sufficient material for 2-3 lectures in a semester-long introductory chemistry course. The PI also plan to involve undergraduate researchers from other US universities in this project by leveraging existing NSF summer REU programs at Stanford, with special attention given to identifying and recruiting promising female and under-represented minority students as summer researchers.
