Fig. 3.

Acidic HER performance of our Pt nanomembranes. a Linear sweep voltammetry (LSV) curves, b Tafel slopes of 5-nm, 10-nm, 19-nm, 28-nm-thick Pt nanomembrane and bulk Pt foil. The inset shows overpotential at 10 mA cm⁻². c Comparison of mass activities measured at 50 mV for our Pt nanomembranes with those of Pt foil and commercial Pt/C. d Stability tests of 19-nm-thick Pt nanomembrane at the current density of 10 mA cm⁻². e Proton exchange membrane water electrolyzer (PEM–WE) device performance using our 19 nm Pt nanomembrane as the cathodic HER catalyst and Commercial IrO₂ as the anodic OER catalyst at room temperature, insets are the schematic (left) and photograph (right) of the PEM–WE. f Comparison of our Pt nanomembranes and other HER electrocatalysts in terms of overpotential at 10 mA cm⁻² and cost per area