Interfacial engineering of defects-enriched RuO2-Co3O4-x/Cobalt Foam heterojunctions with modulated Ru-O-Co electronic bridges for long-term efficient sulfur removal and direct alkaline seawater hydrogen production

The hybrid seawater electrolysis (HSE) system can not only optimize the utilization of seawater resources for low-energy hydrogen production but also offer environmentally friendly sulfur removal for industrial wastewater management. However, developing an active and stable electrocatalyst remains a significant challenge due to the issues of catalyst poisoning and corrosion caused by sulfur precipitates and seawater salts. Herein, the defects-enriched RuO2-Co3O4-x/Cobalt Foam heterojunctions are synthesized in this work, where the hetero-interfaces are inter-modulated by the establishment of octahedral Ru-O-Co electronic bridges. These defects-enriched nanoheterostructures present a good stability of > 1000 hours reacting at 100 mA cm−2 in the HSE system, achieving low-energy-consumed cathodic hydrogen production (FE ≥ 93 %, energy saving ≥ 65 %) in alkaline seawater in conjunction with the anodic sulfur oxidation reaction (SOR) to selectively generate valuable S8 product. Combining with the experimental results of in situ EIS and DEMS for investigating the reaction pathways of SOR and HER, the corresponding DFT studies reveal that the overall d band center and charge transfer behavior are optimized with the formation of Ru-O-Co electronic bridges at RuO2|Co3O4-X hetero-interfaces, thus stabilizing the catalyst structure for seawater hydrogen evolution and decreasing the energy barriers for the rate-determining step of *S3-*S4 in SOR. [Display omitted] •Defects-enriched RuO2-Co3O4-x/CF heterojunctions with Ru-O-Co bridges achieve highly active, selective electrocatalysis.•The bifunctional RuO2-Co3O4-x/CF demonstrated remarkable stability for > 1000 hours for sulfur removal and HER in HSE system.•Critical intermediates in SOR and HER were studied via differential electrochemical mass spectrometry.•DFT calculations illustrate that the heterointerfaces of RuO2|Co3O4-x serve as the critical active sites for SOR.