Figure 4.

(a) Typical pore size distribution of a SGL carbon paper with MPL. The y axis shows the share of the total pore volume for a pore with radius r.¹⁰ (b) Capillary pressure, p_C, calculated with the Young–Laplace equation p_C = – 2γ cos θ r^–1, in which r is the cylindrical pore with radius, θ is the wall contact angle (110°, 130°, 150°), and γ is the electrolyte surface tension (H₂O at 20 °C: γ = 73 mN m^–1). The pore floods with liquid when the differential pressure acting on the pore exceeds the capillary pressure: Δp = p_L – p_G ≥ p_C.