Durable Core‐Shell Nanoporous Catalysts Enabling pH‐Universal and Ampere‐Level Water Splitting

Balancing high catalytic activity with long‐term electrochemical durability remains a significant challenge for practical green hydrogen production, especially under the harsh operating conditions of water electrolysis. Here, we report a robust three‐dimensional core‐shell nanoporous electrocatalyst with a noble metal (NM) skin, synthesized via a two‐step dealloying strategy that exploits the atomic enthalpy difference between noble and transition metals. The resulting core‐shell nanoporous catalyst (NP‐IrNi@Ir) exhibits ultra‐low overpotentials of 102.4, 154.6, and 209.5 mV for the hydrogen evolution reaction (HER) in acidic, alkaline, and alkaline seawater electrolytes, respectively, at an industry‐level current density of 1 A cm −2 . Serving as a bifunctional catalyst for both HER and oxygen evolution reaction (OER), NP‐IrNi@Ir presents overall water splitting voltages of 1.45, 1.50, and 1.46 V in acidic, neutral, and alkaline electrolytes at 10 mA cm −2 . When coupled with a monolithic perovskite‐silicon tandem solar cell, the integrated device attains a remarkable solar‐to‐hydrogen conversion efficiency of 22.4% in alkaline seawater electrolysis, among the highest values reported to date. Notably, NP‐IrNi@Ir exhibits exceptional stability over 2000 h of continuous operation in alkaline natural seawater, with negligible performance degradation, underscoring the outstanding durability of its three‐dimensional core‐shell nanoarchitecture under high‐voltage conditions.