Proton exchange membrane water electrolysis (PEMWE) is a promising technology for regenerative oxygen generation in long-duration space missions and lunar-resource-utilization systems, where mass, volume, reliability, and auxiliary fluid-management requirements are severely constrained. Cathode-fed PEMWE offers a simplified architecture for such oxygen generation systems by supplying water from the hydrogen side and transporting it across the membrane to the oxygen-evolving anode, thereby reducing liquid-water discharge and downstream separation on the oxygen side. However, this configuration shifts the key water-management bottleneck to the cathode-membrane electrode assembly (MEA) interface, where retained H₂ bubbles can block water access, disrupt liquid continuity, and restrict transmembrane water supply. Here, we develop a cathode surface topology engineering (STE) strategy to regulate gas-liquid-solid contact within the MEA interface. The patterned cathode topology weakens bubble contact-line pinning, limits lateral bubble spreading, and promotes earlier H₂ bubble departure while preserving water-access pathways. Bubble-release analysis, transparent-cell visualization, electrochemical stability testing, and impedance measurements reveal that effective STE requires an appropriate morphology window rather than maximized roughness or deformation. Experimental validation under terrestrial gravity conditions (1g) shows that a moderately developed topology enables stable cathode-fed operation, reaching 1.813 V at 1.0 A cm⁻² after 250 min and an average degradation rate of 0.21 mV h⁻¹ during 200 h operation at 0.5 A cm⁻². This work establishes cathode-interface topology as a template-assisted MEA-level strategy for passive two-phase management in lightweight PEMWE oxygen generation systems.

Achieving simultaneous activity and durability for acidic oxygen evolution reaction (OER) remains a central challenge; interfacial heterostructuring offers a route to stabilize Ru while exploiting its high intrinsic activity. Here we report a heterostructured nanosheet catalyst Ir_xRu_1−xO₂/WO₃ that leverages interface-driven electronic and geometric modulation to boost OER performance. Density functional theory calculations indicate that interfacial modulation steers the OER toward the oxide pathway mechanism (OPM), effectively lowering the energy barrier of the potential-determining step. In electrochemical tests, the catalyst delivers an overpotential of 223 mV at 10 mA·cm⁻² under acidic conditions and maintains an essentially constant potential over 120 h of continuous chronopotentiometry. An OER–oxygen reduction reaction (ORR) coupled electrochemical oxygen generator (EOG) single cell was constructed to evaluate the catalyst’s performance, demonstrating a current density of 664 mA·cm⁻² at 1.2 V and an oxygen production rate of 126 mL·min⁻¹. The Ir_xRu_1−xO₂/WO₃ exhibits good stability during 320 h of continuous operation, with a current decay of less than 3%, which is significantly lower than that of the commercial IrO₂ (current decay of ~ 15%). These results establish interfacial heterostructuring as a practical route to combine high activity with long-term durability in acidic OER, enabling efficient, robust electrochemical oxygen generation.

Low-oxygen (O₂) environments are essential in various research and application fields, yet traditional methods like nitrogen flushing or chemical O₂ absorbers face challenges in high equipment cost and low controllability. This study introduces a novel electrochemical oxygen removal (EOR) controller, offering a lightweight, low-cost, and precise low-O₂ control solution. The self-powered EOR controller uses a sacrificial anode to drive the cathodic oxygen reduction reaction (ORR), efficiently consuming environmental O₂ to reduce its level, thus eliminating the requirements of external gas or power sources. By integrating a single-atom ORR catalyst and flexible design, the device achieves a substantial reduction in weight and cost. The incorporation of electronic components for the EOR controller, including a switch for reaching targeted O₂ concentration and a fixed resistor for O₂ removal rate regulation, enables multi-dimensional O₂ removal control. The system also realizes the O₂ concentration estimation in real-time with ±1% accuracy (within the 21%–1% range) by calculating electron transfers. The EOR controller’s effectiveness is validated in plant hypoxia stress experiments, demonstrating precise O₂ level adjustments and its potential across various applications requiring controlled hypoxic conditions.