The Implications of Coupling an Electron Transfer Mediated Oxidation with a Proton Coupled Electron Transfer Reduction in Hybrid Water Electrolysis
Biswajit Mondal, Soumitra Dinda, Neeta Karjule, Sanjit Mondal, Alagar Raja Kottaichamy, Michael Volokh, Menny Shalom
Abstract
Abstract Electrolysis of water is a sustainable route to produce clean hydrogen. Full water‐splitting requires a high applied potential, in part because of the pH‐dependency of the H 2 and O 2 evolution reactions (HER and OER), which are proton‐coupled electron transfer (PCET) reactions. Therefore, the minimum required potential will not change at different pHs. TEMPO [(2,2,6,6‐tetramethyl‐1‐piperidin‐1‐yl)oxyl], a stable free‐radical that undergoes fast electro‐oxidation by a single‐electron transfer (ET) process, is pH‐independent. Here, we show that the combination of PCET and ET processes enables hydrogen production from water at low cell potentials below the theoretical value for full water‐splitting by simple pH adjustment. As a case study, we combined the HER with the oxidation of benzylamine by anodically oxidized TEMPO. The pH‐independent electrocatalytic oxidation of TEMPO permits the operation of a hybrid water‐splitting cell that shows promise to perform at a low cell potential (≈1 V) and neutral pH conditions.