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Updated: Aug 10, 2025

Electrochemically and Bioelectrochemically Induced Ammonium Recovery
Published on: January 22, 2015
Electrochemical sensing mechanism of ammonium ions over an Ag/TiO2 composite electrode modified by hematite
Shilin Zhang1,2,3,4,5, Jinqing Hu2, Sam Fong Yau Li4,5
1Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074, P. R. China. tangaidong@cug.edu.cn.
Abstract:
Here, we demonstrate a new electrochemical sensing mechanism of ammonium ions (NH4+) involving a two-electron oxygen reduction reaction (ORR) and a hydrazine reaction. The NH4+ are electrooxidized to hydrazine by H2O2 derived from the ORR over a self-supporting Ag/TiO2 nanotube array composite electrode modified by hematite (Ag/Fe2O3/TNTs). The Ag/Fe2O3/TNT sensor exhibits a high sensitivity of 1876 µA mM-1 cm-2 with a detection limit of 0.18 µM under non-alkaline conditions, a short response time of 3 s, good reproducibility, and fine selectivity among various interferents, and is also successfully used in real water bodies to display high accuracy. Furthermore, this new mechanism has a certain universality in a range of Ag (main catalyst)/transition metal oxide (cocatalyst)/TNT sensing systems. This work offers a new design basis for the urgently needed electrochemical ammonia nitrogen sensors.
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