How Low Can You Go? Nanoscale Membranes for Efficient Water Electrolysis

Motivated by the need to lower the cost of hydrogen (H-2) production by water electrolysis, significant research efforts are focused on making proton (H+) exchange membrane (PEM) water electrolyzers more efficient and capable of operating at higher current densities. These aims can be met by making H+-conducting membranes thinner, which has the effect of lowering ohmic drops across the membrane that represent the largest efficiency loss at high current densities (>2 A cm(-2)). However, decreasing membrane thickness below 50 mu m is not trivial due to trade-offs between membrane resistance, H(2)crossover (safety), membrane degradation, and manufacturing throughput. Herein, descriptions of key processes, limitations, and trade-offs that arise in thin membranes are provided that can be used to guide the design of ultrathin (i.e., submicron thick), low-resistance membrane materials that have the potential to transform the field of clean H-2 production.