Interfacial Engineering to Construct Two-Dimensional Boron-Doped Iron Disulfide/Metal-Organic Framework Heterostructures for Selective Anodic Reaction in Seawater.

Abstract

Hydrogen production from seawater is promising; however, the complex chemistry and corrosive nature of seawater are a huge bottleneck. Therefore, it is imperative to design catalysts that provide highly active and stable catalytic sites for preferential seawater catalysis. Here, we constructed an interface by heterostructuring boron-doped iron disulfide (B-FeS₂) sheets with metal-organic framework (MOF) sheets to achieve higher activity and longer life, confirmed through theoretical and experimental results. B facilitates Ni-S ionic interactions at the heterointerface with a 2.28 Å bond length, which modulates the electronic properties and the surface chemistry. It also yields borate species at the interface, which act as a local OH^- modulator and favor OH^- adsorption. The presence of SO₄^2- ions on the surface works as a repellent to corrosive Cl^- ions. As a result, the heterostructure achieves an anodic current density of 1.5 A/cm² at an overpotential of 628 mV without chlorine-related reaction and remains stable for over 500 h in seawater. Antichlorine and anticorrosion tests further reveal that the catalyst is highly stable and strongly inhibits chlorine chemistry, further supported by theoretical calculations and ex situ materials analysis. Hence, an ideal pathway to realize H₂ production directly from seawater via materials engineering is presented.