Maximization of hydrogen peroxide utilization in a proton exchange membrane H 2 O 2 electrolyzer for efficient power-to-hydrogen conversion

A hydrogen peroxide electrolyzer (HPEL) is the workhorse for an energy storage system based on the H 2 O 2 electrochemical cycle. The high H 2 O 2 utilization towards power-to-hydrogen conversion in the HPEL is essential to ensure the efficiency and cyclability of the system. Unfortunately, the H 2 O 2 disproportionation at the anode and its crossover to the cathode in a proton exchange membrane (PEM) HPEL is detrimental to H 2 O 2 utilization and must be mitigated. This work investigates the effects of the catalyst type, anode catalyst loading, and PEM thickness on H 2 O 2 utilization in a PEM HPEL. The results show that the Co–N–C catalyst exhibits higher H 2 O 2 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 H 2 O 2 disproportionation reaction (HPDR). Increasing the Co–N–C catalyst loading and PEM thickness can effectively inhibit the H 2 O 2 crossover and improve the H 2 O 2 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 H 2 O 2 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 H 2 O 2 –H 2 cycle.