Maximization of Hydrogen Peroxide Utilization in PEM H2O2 Electrolyzer for Efficient Power-to-Hydrogen Conversion

The hydrogen peroxide electrolyzer (HPEL) is the workhorse for the energy storage system based on the electrochemical cycle of H2O2. The high H2O2 utilization towards power-to-hydrogen conversion (EH2O2-HER) in the HPEL is essential to ensure the efficiency and cyclability of the system. Unfortunately, the disproportionation of H2O2 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 catalyst type, catalyst loading, and membrane thickness on H2O2 utilization in PEM HPEL. The results show that cobalt- and nitrogen-doped carbon (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 loading of the Co-N-C catalyst and membrane thickness can effectively inhibit the H2O2-crossover and improve the H2O2 utilization. On the other hand, the portion of HPDR and the ohmic loss increases with the catalyst loading and membrane thickness, respectively. A maximum H2O2 utilization of over 98% can be achieved by balancing these factors and the cell operating condition. These results provide valuable guides to the catalyst design and device optimization for highly efficient energy storage systems based on the electrochemical H2O2-H2 cycle.