Co‐assembly of a Nafion–Mesoporous Zirconium Phosphate Composite Membrane for PEM Fuel Cells

Abstract

AbstractSynthesis of mesoporous zirconium phosphate (MZP) by co‐assembly of a tri‐block copolymer, namely pluronic‐F127, as a structure‐directing agent, and a mixture of zirconium butoxide and phosphorous trichloride as inorganic precursors is reported. MZP with a specific surface area of 84 m2 g–1, average pore diameter of about 17 nm and pore volume of 0.35 cm3 g–1 has been prepared, and characterised by X‐ray diffraction (XRD) and transmission electron microscopy. Nafion–MZP composite membrane is obtained by employing MZP as a surface‐functionalised solid‐super‐acid‐proton‐conducting medium as well as an inorganic filler with high affinity to absorb water and fast proton‐transport across the electrolyte membrane even under low relative humidity (RH) conditions. The composite membranes have been evaluated in H2/O2 polymer electrolyte fuel cells (PEFCs) at varying RH values between 18 and 100%; a peak power density of 355 mW cm–2 at a load current density of 1,100 mA cm–2 is achieved with the PEFC employing Nafion–MZP composite membrane while operating at optimum temperature (70 °C) under 18% RH and ambient pressure. On operating the PEFC employing Nafion–MZP membrane electrolyte with hydrogen and air feeds at ambient pressure and a RH value of 18%, a peak power density of 285 mW cm–2 at the optimum temperature (60 °C) is achieved. In contrast, operating under identical conditions, a peak power density of only ∼170 mW cm–2 is achieved with the PEFC employing Nafion‐1135 membrane electrolyte.