Industrial-Scale Seawater Splitting at Engineered Interface of Boron-Doped Cobalt Sulfide/Metal–Organic Framework Nanosheets Heterostructure

Seawater electrolysis faces several significant obstacles, including low energy efficiency and anode corrosion due to chlorine chemistry, which limit its practical potential. To overcome this, we developed a catalyst composed of boron-doped CoS₂ protected by metal–organic framework sheets (MOFs) (B-CoS₂/MOF heterostructures). Introducing B atoms into the CoS₂ layer tunes the surface chemistry to promote adhesion of Ni–MOF. Density functional theory calculations indicate a strong interaction at the heterointerface, with a binding energy of −4.13 eV, where the MOF anchors onto the B-CoS₂ surface through a Ni.S bond measuring 2.08 Å, confirming the presence of an ionic bond. This strong heterointerface promotes OH⁻ adsorption while repelling Cl⁻ ions due to the presence of SO₄^2-, effectively mitigating chlorine-induced degradation. Therefore, the B-CoS₂/MOF catalyst achieves an industrial-scale current density of 1.0 A cm⁻² at an overpotential of 542 mV in alkaline seawater and operates stably for 600 h, hence suggesting the potential for designing cost-effective, chlorine-resistant systems for practical seawater splitting.