Cobalt-Doped Ru@RuO₂ Core–Shell Heterostructure for Efficient Acidic Water Oxidation in Low-Ru-Loading Proton Exchange Membrane Water Electrolyzers

Abstract

Proton exchange membrane water electrolysis (PEMWE) is a highly promising hydrogen production technology for enabling a sustainable energy supply. Herein, we synthesize a single-atom Co-doped core–shell heterostructured Ru@RuO 2 (Co-Ru@RuO 2 ) catalyst via a combination of ultrafast pulse-heating and calcination methods as an iridium (Ir)-free and durable oxygen evolution reaction (OER) catalyst in acidic conditions. Co-Ru@RuO 2 exhibits a low overpotential of 203 mV and excellent stability over a 400 h durability test at 10 mA cm –2 . When implemented in industrial PEMWE devices, a current density of 1 A cm –2 is achieved with only 1.58 V under an extremely low catalyst loading of 0.34 mg Ru cm –2, which is decreased by 4 to 6 times as compared to other reported Ru-based catalysts. Even at 500 mA cm –2, the PEMWE device could work stably for more than 200 h. Structural characterizations and density functional theory (DFT) calculations reveal that the single-atom Co doping and the core–shell heterostructure of Ru@RuO 2 modulate the electronic structure of pristine RuO 2, which reduce the energy barriers of OER and improve the stability of surface Ru. This work provides a unique avenue to guide future developments on low-cost PEMWE devices for hydrogen production.