Currently, about half of world’s hydrogen is produced using steam-methane reforming, which produces greenhouse gas, CO2, and thereby puts a significant burden on the environment. To solve this problem, various carbon-free pathways for hydrogen production are under development. Among them, thermochemical water splitting (TWS) has many advantages in that it produces hydrogen in scalable way, and it has the potential to surpasses the efficiency limit of other technologies. Two-step TWS is generally regarded as the most promising TWS approach due to its relative simplicity. In the two-step TWS cycle, a metal oxide (MOx) releases O2 during thermal reduction at high temperature (TH), and becomes oxygen-deficient oxide (MOx-δ), which extracts oxygen ions from water to produce hydrogen during water splitting reaction at a usually lower temperature (TL) (Fig. 1).
Fig. 1 Schematic of two-step thermochemical water splitting
Our lab is developing highly-efficient two-step TWS processes that can compete with the existing steam methane reforming process. For that, we will start with fundamental materials research, in which we will search for novel materials that can overcome limitations of the state-of-the-art materials. We are building efficient laboratory-scale reactors and demonstrating hydrogen production by using the newly-developed materials in the reactors. Potentially, our scope could extend to other water-splitting technologies, not limited to the thermochemical processes, whenever we find them interesting and worthy of further investigation.