Research

Our research aims at understating structure – property relationships in electrochemical materials, mostly metal oxides and hydroxides, and their effect on their function in electrolytic devices for energy conversion and storage. We currently work on electrolytic water splitting to produce green hydrogen, focusing on disruptive decoupled water splitting routes, especially on our recent invention of E-TAC water splitting. This approach offers potential for high efficiency water splitting in a membraneless cell architecture that allows operation under high pressure and dynamic load conditions as provided by solar and wind power. One of the greatest challenges in transforming this new concept into a game changer water splitting technology is overcoming the capacity – rate tradeoff of our charge storage anodes. The anode in our cell divides the oxygen evolution reaction (OER, 4OH → O2 + 2H2O + 4e) into two stages: an electrochemical stage that charges the anode (Ni(OH2) + OH → NiOOH + H2O + e), followed by a chemical stage in which the charged anode reacts with water to produce oxygen and regenerates back to its initial state (4NiOOH + 2H2O → 4Ni(OH)2 + O2). By doing so, the four electron OER is replaced by four one electron Ni(II)/Ni(III) redox reactions, thereby replacing the large OER overpotential (> 0.4 V) by a much smaller overpotential (~0.2 V) in the E-TAC process. This allows high efficiency. However, the anode in our process acts as a charge storage electrode, as in batteries, rather than an inert electrocatalytic electrode, as in conventional water electrolysis. Therefore, the current x time product is limited by the finite charge capacity that can be reversibly charged and regenerated in the E-TAC cycles. Our goal is to develop new materials for high-capacity and high-rate electrodes to allow long E-TAC cycles at high current density and high efficiency.