Nano-sized gold particles driven interfacial reaction for the enhanced electrochemical nitrite sensing

Nitrite is a typical food additive and chemical fertilizer, which could pose toxicity to human and aquatic organisms when it is excessive. Therefore, it is meaningful to develop reliable analytical methods for nitrite detection. In this work, an innovative electrochemical nitrite sensor has been fabricated using In₂O₃ decorated with high-activity nano-sized Au particles (Au/In₂O₃), which were synthesized through a two-step synthetic method combining hydrothermal reaction and deposition-precipitation, resulting in an excellent sensing performance for the nitrite. Specifically, the electrochemical nitrite sensor based on Au/In₂O₃ exhibits high sensitivity with a linear detection range from 10 μM to 5 mM at pH 7.38. Additionally, the Au/In₂O₃ based nitrite sensor shows a detection limit of 0.46 μM and presents impressive selectivity and stability. The extraordinary nitrite sensing performance can be attributed to the excellent catalytic activity of nano-sized Au particles and the strong interfacial reaction between Au/In₂O₃ and nitrite. Furthermore, theoretical calculations reveal the interfacial reactions mechanism driven by Au particles, which enhance the charge transfer between Au/In₂O₃ and nitrite and thus improve its electrochemical sensing performance. This work presents a novel approach towards fabricating high-performance electrochemical nitrite sensor and reveals the enhanced interfacial reaction mechanism of nano-sized Au particles.