As the level of deployment and utilization of renewable energy sources, including wind and solar, continues to rise, large-scale, long-term energy storage technologies that could accommodate weekly and seasonally energy fluctuations will play a significant role in the overall deployment of renewable energies in the future. Storing renewable electrons, using either electrochemical or photoelectrochemical processes, in the form of chemical bonds, e.g., fuels, has the potential to meet the long-term, terra-watt scale energy storage challenge. Renewable hydrogen, in particular, is a centerpiece for renewable fuel production and deep de-carbonization of multiple sectors in our society. Cost-competitive renewable hydrogen can be directly used in the transportation sector for fuel cell cars, in the electric grid sector for electricity firming and load balancing and in the industry sector for metal refineries or biomass upgrading. In addition, coupling with the carbon and nitrogen cycles, renewable hydrogen can be readily processed with known and well-established thermal-chemical processes to generate hydrocarbon fuels and ammonia. Low temperature electrolysis (LTE) and photoelectrochemical (PEC) water-splitting are two different approaches for producing low cost, renewable hydrogen at scale. In LTE, renewable electrons (either from wind or solar for instance) are directed into a membrane electrode assembly with well-engineered reactant and product transport pathways for efficient and stable production of hydrogen. To minimize the device cost, the operating current density of the electrolysis unit often exceeds 1 A cm^-2. In PEC water-splitting, hydrogen is directly produced from sunlight in an integrated photoelectrochemical unit, in which synergistic assembly of light absorbers, electrocatalysts, membrane separators and electrolytes are required for efficient and stable hydrogen production. The operating current density of PEC cell is in the range of 10 mA cm^-2 without solar concentration to 100 mA cm^-2 with solar concentration. While LTE and PEC approaches currently have very different technical readiness level and very different system-level design spaces for future deployment, the two low temperature hydrogen production approaches have many commonalities at the materials level and component level that could potentially benefit from cross-fertilization.

This symposium aims to bring together researchers with diverse disciplines from both the LTE and PEC communities to present and discuss recent advances in the field. Presentations will focus on both fundamental materials discoveries and device level challenges. This symposium will highlight advanced materials characterization, synergistic theory-experiment coupling, and standard protocol developments. Topics will include compound semiconductors for high efficiency solar water-splitting, membrane and electrolyte engineering, high-throughput calculation and experimentation, light materials interaction, advanced photoelectrochemical science, interfacial charge transfer, plasma induced processes, and corrosion science. This symposium will facilitate cross-cutting discussions between the two approaches. Researchers with different expertise attending this symposium will be able to learn from each other and will be exposed to a variety of cross-cutting opportunities for new materials and device developments.

diffusion electron-phonon interactions energy storage metrics oxide polymer simulation standards