Fig. 1

In situ dealloying dynamics of Ir _x Os_(1−x) alloys. a Comparison between total Os (top curves) and Ir (bottom curves) dissolution measured in situ with SPRDE-ICP-MS for Ir₇₅Os₂₅ (green), Ir₅₀Os₅₀ (blue) and Ir₂₅Os₇₅ (red) and Ir-poly (black) under the same conditions (1 mA cm⁻² in 0.1 M HClO₄ at 25 °C) demonstrating significant dissolution of Os, accompanied by a small Ir loss during the dealloying protocol. b Representative SEM images of dealloyed Ir _x Os_(1−x) catalysts revealing a porous architecture, with varying pore size (10–100 nm) and surface-to-volume ratio generated through the dealloying process. c Corresponding cyclic voltammograms (CVs) of dealloyed materials (0.1 M HClO₄ at 50 mV s⁻¹), showing the same pseudocapacitive (OH_ad) profiles and peak position but with increasing current density for higher Os contents in the alloy, indicative of higher ECSA and negligible electronic effect of Os content in the alloy