Determination of Mn2+ by a paper-based flexible electrochemical sensor modified by NiFe2O4 and CeO2 nanoparticles

Abstract

NiFe₂O₄, a spinel compound, has drawn significant interest from researchers due to its high natural saturation and remarkable electrocatalytic properties. Simultaneously, CeO₂ introduces structural defects that can enhance the functional properties of materials. Besides, synthesizing these compounds in nanoparticles imparts unique characteristics which often absent in their normal forms. In this study, we presented a paper-based electrochemical sensor, developed by modification of NiFe₂O₄ and CeO₂ nanoparticles onto a laser-induced graphene (LIG) electrode. Various characterization approaches were used to portray the morphological structure of the electrode along with appraise the electrochemical performance of the electrode. These analyses demonstrate that NiFe₂O₄ and CeO₂ nanoparticles can enhance electron transfer and improve the electrocatalytic properties of the sensor. The nanoparticles boost the electrode's surface together with creating more extra active sites for improved detection. Density Functional Theory (DFT) calculation further illustrated that the interaction between two nanoparticles do help to improve electron transfer and adsorption abilities of the electrode together. The sensor exhibits a wide linear range from 8 µg/L to 2 mg/L, a low limit of detection (LOD) of 1.72 µg/L as well as distinguished anti-interference ability and reproducibility beneath optimized conditions. This sensor was successfully used in detecting Mn²⁺ in real groundwater samples accurately. This study offers a promising way for rapid, portable and accurate detection of Mn²⁺ by using a paper-based electrochemical sensor.