Title : Single-Atom Ru engineering in Co3O4 tailors metal-oxygen covalency for oxide path mechanism-driven acidic water oxidation
Abstract:
Proton exchange membrane water electrolyzer (PEMWE) offers a scalable route to green hydrogen production but is hindered by the instability of acidic oxygen evolution reaction (OER) catalysts. While Ru-based materials show promise, their high cost and susceptibility to corrosion limit practical deployment. Here, we report a single-atom Ru doped Co3O4 catalyst via electrodeposition and cation exchange, where Ru atoms selectively occupy octahedral Co3+ sites. This atomic engineering weakens metal-oxygen (Ru/Co-O) covalency, enhancing structural flexibility to promote the oxide path mechanism (OPM)—bypassing lattice oxygen participation—as confirmed by operando Raman and FT-IR spectroscopy and TMA+ probe experiments. The resulting catalyst achieves an overpotential of 173 mV at 10 mA cm-2 in 0.5 M H2SO4 and operates stably for 2623 hours (>3.6 months) with a negligible decay rate of 0.011 mV h-1, outperforming most noble metal-doped Co3O4 benchmarks. Crucially, the ultralow Ru loading (4.46 wt.%) reduces noble metal costs to USD $0.00064 cm-2.
During prolonged operation, in situ formation of RuO2/Ru-doped Co3O4 heterojunction further stablizes the catalyst, with Ru-doped Co3O4 acting as an electron reservoir to suppress Ru overoxidation. Membrane electrode assembly tests further validate its practicality for proton exchange membrane electrolyzers (PEMWE). This work demonstrates that tailoring metal-oxygen covalency through single-atom doping can strategically regulate OER pathways and interfacial dynamics, offering a generalizable design principle for durable acidic electrocatalysts. Our findings pave the way for developing self-optimizing heterostructures and oxyphilic dopant libraries to advance green hydrogen technologies.
