Modular design of an efficient heterostructured FeS2/TiO2 oxygen evolution electrocatalyst via sulfidation of natural ilmenites

Abstract

Developing cost-effective and durable catalysts for the oxygen evolution reaction (OER) is of great interest for advanced energy conversion and carbon neutrality schemes. Here, we demonstrate a modular design strategy to engineer an efficient heterostructured electrocatalyst FeS₂/TiO₂ (S-FTO) via a sulfidation process on natural ilmenites (FTO), which integrates high OER activity, good conductivity, and high stability. The modular catalyst, S-FTO catalyst, shows a low overpotential of 230 mV to achieve 10 mA cm⁻², as well as excellent stability in alkaline solution. Typically, S-FTO exhibits OER activity 19 times higher than FTO at an overpotential of 300 mV. In-depth investigations indicate that the high OER activity of S-FTO mainly originates from accelerated surface self-reconstruction induced by lattice S etching within the OER potential region, and the newly formed FeOOH on the outer layer acts as the active species for the OER. The remaining FeS₂ regulates the surface electronic properties and enhances the conductivity, while TiO₂ improves the stability. The modular design strategy demonstrated here will enable the design of low-cost heterostructures as high-efficiency catalysts for challenging energy storage/conversion reactions in an eco-friendly and sustainable manner.