Pt Nanoparticles Supported on Ta-Doped TiO2 for Durable Proton Exchange Membrane Water Electrolysis

Platinum (Pt) is more earth-abundant and corrosion-resistant than iridium (Ir), yet its deployment as an acidic oxygen anode has been abandoned due to the formation of a self-passivating, insulating PtO2 film. Here, we show that this century-old bottleneck can be alleviated by an electron-shuttling junction in which Pt nanoparticles are anchored to a tantalum (Ta)-doped titanium dioxide support, with Fermi level higher than Pt. The built-in contact potential injects electrons into Pt via Pt-O-Ta/Ti bridges and continuously bleeds the bypass oxygen evolution electrons to Pt at high bias, thereby suppressing the formation of a passivating α-PtO2 layer. In situ spectroscopies reveal the successful preservation of Pt 5d occupancy, along with strengthened surficial water adsorption (alleviated reversed Stark effect of νOH). The assembled electrolyzer, with a Pt loading of only 350 μgPt cm-2, achieves 3 A cm-2 at 2.262 V and operates for 1500 h under 1 A cm-2 without noticeable passivation. Life cycle cost analysis estimates a green hydrogen price of US$1.56 kg-1, below both the US DOE 2026 target and the costs of contemporary alkaline electrolyzers. This concept relocates the stability problem from the noble metal to a tunable oxide, providing a general blueprint for passivation-free, platinum-based acid water-splitting catalysts.