A highly selective copper-tin alloy nanosheet/carbon-paper sensitive electrode for detecting nitrite at low electrochemical reduction potential based on a binary cooperative strategy

Abstract

Although the use of catalytic reduction low potential to detect NO₂^– can effectively solve the traditional problem of high working bias of electrochemical nitrite sensors, the reduction potential of NO₂^– is similar to that of other nitrogen-containing inorganic substances (NO₃^–), which leads to the inevitable interference of nitrate in the working process of the electrode, resulting in reduced electrode selectivity. In this study, the transition metal alloying method was used to solve this challenge, that is, based on the synergistic effect between the catalytic reduction characteristics of copper’s high-occupying D-orbital and the strong adsorption capacity of tin to oxygen. The copper-tin alloy nanosheet/carbon paper sensitive electrode (CuSn/CP) prepared by one-step electrodeposition was used for electrochemical detection of NO₂^–. The electrochemical test results show that the sensitive electrode has many excellent properties in nitrite detection: the detection potential is as low as −0.08 V vs.Hg/HgO, the sensitivity is as high as 4920µA·mM⁻¹ cm⁻¹, the detection limit is as low as 0.089 μM, and it shows strong anti-interference ability and good stability. Theoretical calculations further confirm that these excellent properties are due to the strong adsorption and electron transfer ability of copper-tin alloy for NO₂^–. The above results prove that the transition metal alloy sensitive electrode can detect nitrite efficiently and quickly to avoid NO₃^– interference, and at the same time, it has a low detection potential and strong stability, which provides a reference for the study of electrochemical nitrite low potential detection.