Catalyst development for low-cost large-scale sustainable hydrogen production from seawater and renewable energy

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Hydrogen is considered one of the most promising clean energy carriers, thanks to its high gravimetric energy density (142 MJ/kg) and environmentally friendly use. It is a clean and desirable way to produce pure hydrogen at the cathode via electrolysis of water driven by renewable energy, however, the water splitting is highly dependent on having an efficient and stable oxygen evolution reaction (OER) at the anode, to counterbalance the hydrogen evolution reaction (HER) at the cathode. Furthermore, if water splitting is used to store a substantial portion of the world's energy, water distribution issues may arise if vast amounts of purified water are used for hydrogen fuel production. On the other hand, seawater is the most abundant aqueous electrolyte feedstock on Earth but its implementation in the water-splitting process presents many challenges, especially for the anodic reaction.The most serious challenges in seawater splitting are posed by the chloride anions (around 0.5 M in seawater). Under acidic conditions, the OER equilibrium potential is only slightly higher than that of chlorine evolution, e.g., by 0.130 V, and in fact the OER is a four-electron oxidation requiring a high over potential while chlorine evolution is a facile two-electron oxidation with a kinetic advantage. While chlorine is a high value product, the amount of chlorine that would be generated to supply the world with hydrogen would quickly exceed demand. Nevertheless, under alkaline conditions, the equilibrium potential of OER is significantly shifted to lower value but that of chorine evolution does not change so much, which facilitates OER over chorine evolution with 0.490 V difference in potential domain. Therefore, this project aims to develop highly efficient OER catalysts with over potential less than 0.480 V under alkaline conditions, as well as highly efficient and low cost HER catalysts such as transitional metal carbides and nitrogen doped carbon nanomaterials.