One-pot hydrothermal of Interface-Functionalized of Hematite Nanocrystals for Enhanced Oxygen Evolution Reaction

Abstract

This report presents a novel methodology for the surface fabrication of electrocatalysts, where hematite is interface-functionalized using organic ligands to enhance the oxygen evolution reaction (OER) performance. All the synthesized samples exhibit a nanoparticle morphology and a crystalline structure consistent with hematite, which is the most stable iron oxide. The functional groups from benzimidazole (bIm) and/or caffeine (Caf) serve as scaffolds and sources of carbon, hydrogen, oxygen, and nitrogen, facilitating metal-support interactions (MSIs) to enhance OER activity. The optimal catalyst, Fe- (bIm)0.3Caf, is synthesized by a combination of predominantly bIm with 30% Caf substitution, which introduces defects and oxygen vacancies, resulting in superior OER performance compared to single-ligand counterparts. The Fe-(bIm)0.3Caf catalyst exhibits the lowest overpotential of 264 mV at 10 mA cm−2 and the smallest Tafel slope of 30 mV dec−1 , outperforming commercial Fe2O3. This highlights the importance of the surface engineering strategy, which modifies the surface and electronic structure of metal nanostructures to achieve efficient OER activity. The report outlines a one-pot hydrothermal process for preparing interface-functionalized hematite nanocrystals at low temperatures, offering a promising approach for achieving efficient and durable OER electrocatalysts.