Ultrastable Ti@Ir core-shell catalyst with low iridium loading for water electrolysis at industrial-level current density

Despite proton exchange membrane water electrolysis (PEMWE) being a commercially viable method for high-purity hydrogen production, the development of active and robust anode electrocatalysts with reduced iridium loading under high current density conditions remains highly challenging. Here, we report a core-shell nanostructured catalyst with a metallic titanium core uniformly covered by Ir nanoparticles (Ti@Ir). The spontaneously formed TiO x layer can effectively disperse Ir nanoparticles via interfacial Ti-O-Ir bonds, which in turn increases the oxidation state of Ir towards activated lattice oxygen reactivity, as confirmed by in-situ differential electrochemical mass spectrometry (DEMS). As a result, the Ti@Ir exhibits an overpotential of only 272 mV to reach 10 mA cm −2 , 17 mV lower than non-supported Ir nanoparticles, and a 3.82-fold higher mass activity at 1.53 V. Moreover, the Ti@Ir catalyst demonstrates strong stability during a 100-hour test at 10 mA cm −2 . Detailed analysis reveals that the oxidation of iridium close to the titanium core is suppressed. The huge potential for practical application is further confirmed in a PEMWE prototype, with a low iridium loading of 0.5 mg Ir cm −2 , significantly lower than the typical 2 ∼ 4 mg Ir cm −2 required for traditional catalysts. This Ti@Ir catalyst achieves a cell voltage of 1.858 V at an industrial-level current density of 2 A cm −2 and maintains stable operation for 1800 h with an exceptionally low voltage degradation rate of only 1.252 μV h −1 .