Maximization of hydrogen peroxide utilization in a proton exchange membrane H2O2 electrolyzer for efficient power-to-hydrogen conversion

Abstract

A hydrogen peroxide electrolyzer (HPEL) is the workhorse for an energy storage system based on the H₂O₂ electrochemical cycle. The high H₂O₂ utilization towards power-to-hydrogen conversion in the HPEL is essential to ensure the efficiency and cyclability of the system. Unfortunately, the H₂O₂ disproportionation at the anode and its crossover to the cathode in a proton exchange membrane (PEM) HPEL is detrimental to H₂O₂ utilization and must be mitigated. This work investigates the effects of the catalyst type, anode catalyst loading, and PEM thickness on H₂O₂ utilization in a PEM HPEL. The results show that the Co–N–C catalyst exhibits higher H₂O₂ utilization than the Fe–N–C and Pt/C catalysts due to its higher selectivity towards the hydrogen peroxide oxidation reaction (HPOR) and the lesser H₂O₂ disproportionation reaction (HPDR). Increasing the Co–N–C catalyst loading and PEM thickness can effectively inhibit the H₂O₂ crossover and improve the H₂O₂ utilization. On the other hand, the portion of the HPDR and the ohmic loss increase with the catalyst loading and PEM thickness, respectively. A maximum H₂O₂ utilization of over 98% can be achieved by balancing these factors. These results provide valuable guides to the catalyst design and device optimization for efficient energy storage systems based on the electrochemical H₂O₂–H₂ cycle.