STTR Phase I: Zinc-Assisted Two-Step Electrolyzer for Clean Hydrogen Production Using Low Purity Water

The broader/commercial impact of this Small Business Technology Transfer (STTR) Phase I project is to enable small-scale hydrogen users to produce their own hydrogen fuel on-site and on-demand. Currently, delivering hydrogen to end users requires the use of highly pressurized tanks, which can be expensive for small-scale users and raise safety concerns. To tackle this issue, this STTR Phase I project will develop a compact, portable device that generates clean hydrogen fuel using energy from sunlight or wind. This will allow for clean hydrogen production exactly where it is needed and when it is needed, with applications ranging from hydrogen fuel cell drones and forklifts to heavy-duty trucks. Additionally, this device, which is made from materials abundant in the U.S., will store renewable energy, allowing users to produce hydrogen even when sunlight or wind energy is unavailable. This innovation aims to make hydrogen a more accessible and affordable energy source, particularly for those who lack reliable access to traditional power grids. Conventional water electrolyzers that split water into hydrogen fuel and oxygen require high-purity water and cannot produce hydrogen off-grid. Producing hydrogen off-grid, on-site, and on-demand using low-purity water is desirable for many applications. This project aims to address the limitation of conventional electrolyzers by developing an innovative zinc-assisted two-step electrolyzer that uses low-purity water to produce hydrogen off-grid, on-site, and on-demand. In step #1, hydrogen is produced when activated zinc spontaneously reacts with water, without requiring electrical energy input. This reaction converts the activated zinc into zinc oxide. In step #2, oxygen is produced when electrical energy (e.g., from renewable sources) is used to electrochemically convert the spent zinc oxide back to activated Zn, regenerating it for reuse in the next cycle. The electrochemical conversion of the inactive zinc oxide back to activated Zn stores renewable energy in Zn, that is effectively used to produce hydrogen in the next cycle. This STTR project will support the development of a prototype commercial-scale two-step electrolyzer by overcoming two technical hurdles: (i) First, reducing the high reaction overpotentials that arise during oxygen evolution in practical commercial-scale electrodes. This will require transitioning from small-sized electrodes with low mass loading to large-sized electrodes with high mass loading. (ii) Second, finding operating conditions that enable the use of non-desalinated seawater in the two-step electrolyzer. These conditions must not allow the formation of unwanted side products that can degrade the activated zinc. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.