Thermal-Tolerant CdPS₃-Polybenzimidazole Membranes with High Proton Conductivity

Abstract

Thermal-tolerant proton-exchange membranes are highly demanded for updating hydrogen–electricity conversion technologies, since the high-temperature operation is expected to suppress the catalyst poisoning of fuel cells or to increase the efficiency of water (steam) electrolysis. But it is still challenged by both stability and conductivity. Herein, two-dimensional CdPS3 nanosheets with atomically in-plane defects were synthesized and employed for the preparation of proton-conductive and thermal-tolerant membranes with polybenzimidazole (PBI). Ultrathin and Cd vacancy-containing CdPS3 two-dimensional (2D) nanolayers were successfully obtained from bulk CdPS3 crystals by ion treatments. The resultant CdPS-PBI hybrid membranes exhibit reliable long-term conductivity stability for 170 h at 180 °C and a maximum proton conductivity of 539 mS cm–1 at 200 °C, which is 1 order of magnitude higher than PBI membranes and the reported polymeric membranes. The proton-transport performance over hybrid membranes was ascribed to abundant proton donor centers, easy proton desorption, and excellent hydration of Cd vacancies on CdPS nanolayers. Therefore, the CdPS-PBI membranes with well-proven chemical/mechanical/thermal stabilities and high proton conductivity would meet the requirements of proton-exchange membranes (PEMs) for high-temperature operations.