A nitrogen and phosphorus enriched inorganic–organic hybrid material for electrochemical detection of selenium(<scp>iv</scp>) ions

A heteroatom (nitrogen and phosphorus) enriched pyridinic bridged inorganic-organic hybrid material (HPHM) was synthesized by polycondensing phosphonitrilic chloride trimer (PNC) and 2,6-diaminopyridine in DMSO at 140 °C. The synthesized material was used as an efficient electrode material for the electrochemical detection of selenium(iv) ions [Se(iv)] in aqueous solution. The HPHM electrode (active mass loading of 4.1 mg cm^-2) achieves a detection range of 5-50 ppb at a deposition potential of -1.2 V and a deposition time of 170 s with a lower limit of detection (LOD) of 2.18 ppb. This LOD is significantly below the World Health Organization's (WHO) recommended maximum level for selenium in drinking water. Moreover, the electrode material maintains high selectivity for Se(iv) ions in the presence of various interfering ions and high sensitivity over 200 cycles with only a minimal (∼6.83%) decline in current density response. The higher Se(iv) ion detection capability is attributed to the strategic incorporation of nitrogen and phosphorus heteroatoms, enhancing the material's electrochemical properties.