MOF-Templated Defective α-Fe ₂O ₃/ZrO ₂ with Phase Junction for Boosting Acetic Acid Sensing

Abstract

Maximizing active sites and increasing charge carriers are effective approaches to achieve excellent gas-sensing performance of metal oxides. Herein, we report a facile route to modulate the α-Fe₂O₃/ZrO₂ composite with defects and phase junctions, obtained from calcination using a zirconium-ferrocene metal-organic framework (ZrFc MOF) as sacrificial precursor coupled with reduced graphene oxide (rGO) as template. In this case, the rGO in the precursors contributes to generate the oxygen vacancies (V_O) and monoclinic/tetragonal ZrO₂ phase junctions. Mechanistic studies uncover that the co-presence of the junctions (hetero- and phase-junctions) and V_O enable to promote the carrier migration and assembly at interfaces, capable of strongly gather the adsorbed oxygen ions, consequently generating an uphill response to acetic acid. This work presents a combinatorial strategy including defect engineering and junction structures which provides new insight into rational design of high-performance sensing materials.

Keywords: ZrFc-MOF, α-Fe2O3, m/t-ZrO2, phase-junction, acetic acid sensor