Novel bifunctional fillers (ATP/P–CNOs) for sulfonated poly(aryl ether sulfone) matrix for improved power output and durability of H2/O2 fuel cell at low humidity

The preparation of novel composite proton exchange membranes (PEMs) with homogeneous structures and efficient proton-conducting sites is of great importance for the development of PEM fuel cells. In this work, a double-filler of adenosine triphosphate (ATP) and phosphorylated carbon nano-onions (P–CNOs) is incorporated into sulfonated poly(aryl ether sulfone) (SPAES) by simple solution mixing to design a bionic proton-conduction pathways for high-performance PEMs. A series of uniformly distributed, dense and flexible SPAES/ATP/P–CNOs membranes are prepared and characterized for their membrane morphology, water uptake, dimensional stability, electrochemical properties and durability. Both the ATP and P–CNOs fillers can provide abundant proton conducting sites through hydrogen-bonding networks and acid-base pairs, thus improving the membrane stability and proton conductivity. Thanks to the formation of ionic interaction between ATP/P–CNOs and their interaction with SPAES substrates, the composite membranes demonstrate higher ATP retention, better dimensional-mechanical-chemical stability, higher proton conductivity and power output than the pristine and single-filler SPAES membranes. The SPAES/ATP/P–CNOs-2 membrane displays high proton conductivity (196 mS/cm at 90 °C in water and 33 mS/cm at 80 °C/51% relative humidity, RH) and power output (752 mW/cm2 at 80 °C/100% RH and 302 mW/cm2 at 80 °C/50% RH) in a H2/O2 fuel cell. It also experiences the minimal cell performance loss and lowest hydrogen crossover during 6 days of operation at 60% RH. The proposed ATP/P–CNOs channel approach can provide a reference for the development of multi-component composite high-efficiency PEMs for fuel cells.