NiTe@NiMo/NF electrodes show outstanding electrocatalytic performance for sulfion oxidation in seawater, able to stably operate at a high current density under a low voltage, simultaneously producing H₂ and sulfur in an energy-saving manner.

Proton exchange membrane water electrolysis (PEMWE) is a key technology for sustainable hydrogen production; however, its efficiency is limited by the sluggish kinetics and high overpotential of the anodic oxygen evolution reaction (OER). Although RuO₂ offers a cost-effective alternative to scarce IrO₂-based catalysts, its application is impeded by a fundamental trade-off between activity and stability under acidic conditions. Herein, we incorporate Hafnium (Hf) into the RuO₂ lattice to modulate the Ru oxidation state and oxygen vacancy concentration. The introduction of Hf suppresses Ru overoxidation, while controlled generation of oxygen vacancies minimizes lattice oxygen participation. The optimized Hf_0.1Ru_0.9O₂ catalyst exhibits a low overpotential of 187 mV at 10 mA cm^-2 and outstanding durability, maintaining performance for 1500 hours in 0.5 M H₂SO₄. Notably, a practical PEMWE device employing this catalyst achieves stable operation for over 600 hours at 500 mA cm^-2. A combination of in-situ differential electrochemical mass spectrometry (DEMS) and operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) reveal that Hf_0.1Ru_0.9O₂ facilitates oxygen evolution primarily through a multiple-pathway mechanism dominated by the adsorbate evolution mechanism (AEM) and the oxide pathway mechanism (OPM), with effectively suppressed lattice oxygen-mediated mechanism (LOM). These findings establish a new design principle for the development of durable acidic OER electrocatalysts.

Widespread deployment of proton exchange membrane water electrolyzers (PEMWE) relies on acid-stable oxygen evolution reaction (OER) catalysts capable of operating at high current densities. Inspired by the robust chemistry of lead-acid batteries, we introduce lead (Pb) into ruthenium-iridium mixed oxide (RuIrO _x ) through a facile sol–gel method. The as-prepared RuIrPbO _x nanoparticulate catalysts with the optimal composition (Ru _0.5 Ir _0.4 Pb _0.1 O _x ) achieve an overpotential of 241 mV at 10 mA cm ⁻² and exceptional stability of 1000 h at a high current density of 100 mA cm ⁻² without degradation. In situ differential electrochemical mass spectrometry indicates that doping RuIrO _x with an appropriate amount of Pb helps to suppress the participation of lattice oxygen during OER, contributing to structural preservation and long-term stability. Density functional theory calculations reveal that Pb doping effectively regulates the electronic structure of the Ru sites, reducing Ru–O covalency, which in turn increases the Ru dissolution energy and therefore prevents Ru leaching—a key degradation pathway for Ru-containing OER catalysts. When integrated into a membrane electrode assembly, the PEMWE cell can operate at a large current density of 3.0 A cm ⁻² under 1.96 V (at 60 °C) for 400 h with minimal performance degradation, demonstrating the significant potential of the Ru _0.5 Ir _0.4 Pb _0.1 O _x as an efficient and durable OER catalyst for practical applications under demanding conditions.