Creating green fuels from electrochemical reactions remains a key goal for an electrified, decarbonized, and regenerative society.[1] In particular, the electrolysis of water to produce Hydrogen and Oxygen is of utmost importance not only as a fuel, but also for a wide range of industrial processes. This importance has led to many studies focused on optimizing the water electrolysis reactions. Most electrolytic reactions are performed in concentrated alkaline conditions, lowering the potential required for the energetically unfavorable oxygen evolution half reaction (OER). However, alkaline membrane electrolyzer also present key problems in electrolyzer stability, high material costs, and safety risks which must be addressed – ideally using neutral [2] or mildly acidic electrolytes. Shifting the electrolyte to an acidic system overcomes many of these challenges, however is limited by the lack of stable catalysts for the acidic OER.
This talk will detail the development of sequential decoupled electrolysis, using Pt and TiO2 in mild acids.[3] In decoupled electrolysis the OER and the hydrogen evolution reaction (HER) are performed sequentially on the same catalyst. Here, we achieve this using TiO2 nanoparticles to store (intercalate) H+ produced during the OER, which are in turn released to drive the HER. The process is highly reversible, showing exceptional stability for over 1000 cycles. The overall efficiency of the decoupled water splitting reaction was calculated as 52.4% providing a promising pathway for acidic water electrolysis.
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