Pore-controlled carbon nanotube sheet anodes for proton/anion-exchange membrane water electrolyzers

The commercialization of proton/anion-exchange membrane water electrolyzers (PEMWEs/AEMWEs) requires the development of high-performance and durable anodes. Herein, pore-controlled electrodes (C@PCEs) that incorporate carbon nanotube sheets with square pores and catalyst nanoparticles are designed. Ir and NiFe catalysts, which promote the oxygen evolution reaction under acidic and alkaline conditions, respectively, are applied in PEMWEs and AEMWEs. The C@PCEs have higher catalytic activities than the corresponding conventional densely packed electrodes (C@DPEs). Additionally, the PEMWEs and AEMWEs with C@PCEs exhibit improved performance with reduced overpotentials compared to those with C@DPEs. This enhancement in performance is ascribed to the pore structure of the C@PCEs, in which the electrocatalyst is well dispersed without agglomeration, thus increasing the electrochemical surface area. In addition, the highly conductive and porous carbon nanotube framework promotes electron and mass transfer. These results demonstrate that the C@PCE design is promising for anodes in both PEMWEs and AEMWEs.