Electrochemical sensing mechanism of ammonium ions over an Ag/TiO2 composite electrode modified by hematite

• DOI: 10.1039/d3cc00240c
• Publication Date: 2023-02-02T16:03:03Z
• Authors: Shilin Zhang; Jinqing Hu; Sam Fong Yau Li; Hongxiu Lu; Gang Wang; Chang Lu; Muhammad Tariq Sa...; Aidong Tang; Huaming Yang
• Keywords: 01 natural sciences; 0104 chemical sciences

Here, we demonstrate a new electrochemical sensing mechanism of ammonium ions (NH4+) involving two-electron oxygen reduction reaction (ORR) and hydrazine reaction. The NH4+ are electrooxidized to by H2O2 derived from the ORR over self-supporting Ag/TiO2 nanotube array composite electrode modified hematite (Ag/Fe2O3/TNTs). Ag/Fe2O3/TNT sensor exhibits high sensitivity 1876 µA mM-1 cm-2 with detection limit 0.18 µM under non-alkaline conditions, short response time 3 s, good reproducibility, fine selectivity among various interferents, is also successfully used in real water bodies display accuracy. Furthermore, this has certain universality range Ag (main catalyst)/transition metal oxide (cocatalyst)/TNT systems. This work offers design basis for urgently needed ammonia nitrogen sensors.