A Physical Insight of Phase-Dependent Electron Transfer Kinetic Behaviors and Electrocatalytic Activity of an Iron Oxide-Based Sensing Nanoplatform Towards Chloramphenicol

Abstract

Insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures is important in the rational design of functional nanostructures for realizing high-performance electrochemical sensors. This study focuses on elucidating the effect of the crystalline phase on the electron transfer kinetics and electrocatalytic activity of iron(III) oxide. The α-FeOOH, γ-Fe2O3, and α-Fe2O3 nanorods were designed by using a simple chemical method and calcining process. The phase-dependent difference in the electron transfer kinetics and electrocatalytic activity toward the sensitive response of chloramphenicol (CAP) is observed by the transformation from α-FeOOH to γ-Fe2O3, and from α-FeOOH to α-Fe2O3 nanorods. We found that the oxygen vacancies formed in phase transformation from α-FeOOH to α-Fe2O3 is a key factor in promoting the electrochemical reduction of chloramphenicol. The α-Fe2O3 nanorods-based electrochemical sensors showed a linear response in the CAP concentration range from 0.1 to 75 μM with a limit of detection of 60 nM and an electrochemical sensitivity of 2.86 μA μM−1 cm−2. This work further provides valuable physical insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures for the rational design of sensing interface.