Dense-Packed RuO Nanorods with In Situ Generated Metal Vacancies Loaded on SnO Nanocubes for Proton Exchange Membrane Water Electrolyzer with Ultra-Low Noble Metal Loading.

Proton exchange membrane water electrolyzer (PEMWE) is a green hydrogen production technology that can be coupled with intermittent power sources such as wind and photoelectric power. To achieve cost-effective operations, low noble metal loading on the anode catalyst layer is desired. In this study, a catalyst with RuO nanorods coated outside SnO nanocubes is designed, which forms continuous networks and provides high conductivity. This allows for the reduction of Ru contents in catalysts. Furthermore, the structure evolutions on the RuO surface are carefully investigated. The etched RuO surfaces are seen as the consequence of Co leaching, and theoretical calculations demonstrate that it is more effective in driving oxygen evolution. For electrochemical tests, the catalysts with 23 wt% Ru exhibit an overpotential of 178 mV at 10 mA cm , which is much higher than most state-of-art oxygen evolution catalysts. In a practical PEMWE, the noble metal Ru loading on the anode side is only 0.3 mg cm . The cell achieves 1.61 V at 1 A cm and proper stability at 500 mA cm , demonstrating the effectiveness of the designed catalyst.