Technoeconomically Viable Ensembles of Artificial Photosynthetic Nanoreactors for Solar Water Splitting

Abstract: 
In 2021, the U.S. Department of Energy (DOE) announced its first Energy Earthshot on Clean Hydrogen, with a production cost target of $1 per kg-H2 by 2031. To put this value in perspective, astonishingly, 80% of it is required for OpEx costs alone, assuming future utility-scale electricity from photovoltaics driving ambient-temperature water electrolysis at its thermodynamic minimum. This fact motivates less-expensive means than photovoltaics to generate and collect photogenerated mobile charge carriers, and/or exceedingly low capital cost electrochemical reactors operating with exceptionally low overpotentials. This latter option represents a paradigm shift from state-of-the-art electrolyzers that currently benefit from operation at high current densities, and thus relatively high overpotentials.

Optically thin photosynthetic nanoreactors transmit significant amounts of sunlight, and therefore each operates at a low current density. When combined with the multiplicative output of having many nanoreactors in an ensemble, detailed-balance solar-to-hydrogen energy conversion efficiencies are simulated to exceed those of optically thick photoelectrochemical designs. In efforts to attain these predicted higher efficiencies, we are performing detailed studies on the properties of state-of-the-art doped SrTiO3 and BiVO4 photocatalyst nanoparticles. This work is funded through a DOE EERE HydroGEN project, and constitutes the basis for a newly awarded DOE Energy Frontier Research Center (EFRC) called Ensembles of Photosynthetic Nanoreactors (EPN), which I direct.

During my talk, I will share our recent collaborative discoveries in atomic-layer deposited ultrathin oxide coatings to impart redox selectivity and materials stability, single-photocatalyst-nanoparticle photoelectrochemical behavior and mobile charge carrier properties, and atomic-level information on dopant distributions and materials interfaces obtained from electron microscopies and X-ray spectroscopies. I will also describe a new low-cost reactor design that we are working to demonstrate experimentally. Collectively, our discoveries provide new design guidelines, and motivate additional research pathways, for the development of effective composite materials to serve as active components in technoeconomically-viable artificial photosynthetic devices.

Biography:
Shane obtained a B.S. Degree in Mathematics, with a concentration in Computer Programming, from Towson University. He subsequently worked as a software engineer, community college instructor, and high school teacher, and also tried out for a professional indoor soccer team. Shane then obtained an M.S. Degree in Nutrition from the University of Maryland, College Park, and M.A. and Ph.D. Degrees in Photo-Physical Inorganic Chemistry from the Johns Hopkins University. He was also a DOE–EERE Postdoctoral Research Awardee at the California Institute of Technology.

Shane has been a faculty member at the University of California Irvine since 2013 and is currently a full Professor in the Department of Chemistry, holding courtesy joint appointments in the Departments of Materials Science & Engineering and Chemical & Biomolecular Engineering. He oversees the Ardo Group (chem.uci.edu/~ardo), a diverse team of innovators and educators that are allies for change. Their research spans solar energy conversion, carbon capture, and clean water, with specific expertise in photochemistry, electrochemistry, membranes, and ionics. Shane is the Director of Ensembles of Photosynthetic Nanoreactors (EPN, photosynthesis.uci.edu) – a DOE Energy Frontier Research Center founded in 2022 – is a member of the Liquid Sunlight Alliance (LiSA, www.liquidsunlightalliance.orghttp://www.liquidsunlightalliance.org/) – a DOE Energy Innovation Hub founded in 2020 – and is the lead for broadening participation in the Center for Interfacial Ionics (CI2, ionics.uoregon.edu) – an NSF Center for Chemical Innovation founded in 2022. Shane is also a recipient of a DOE Early Career Research Award and two Beall Innovation Awards, and was named one of five inaugural Moore Inventor Fellows, a Sloan Research Fellow, a Cottrell Scholar, a Kavli Fellow, a Scialog Fellow, and a UCI Faculty Innovation Fellow.