Biomimetic hydrophobic gating in MXene polypyrrole–based artificial Ion channels for efficient perchlorate sensing

Abstract Ion selective electrodes represent a promising approach for ion detection based on potentiometric sensing principle. However, their practical application is often hampered by insufficient selectivity, primarily caused by interference from structurally similar ions. Herein, inspired by biological potassium ion channels, we demonstrate an efficient perchlorate ion selective electrode via the self–assembly of pyrrole–functionalized MXene nanosheets and methylated quaternary ammonium compounds. The resulting composite sensor significantly outperforms commercial ion selective electrodes with a > 10 4 –fold lower detection limit (10 –9.7 M), 18–fold higher selectivity ( K ij of 130.4), and a maximum sensitivity up to 59.6 mV/dec for perchlorate. Synchrotron X–ray scattering and mechanistic studies attribute this superior performance to a hydrophobic gating mechanism arising from dehydration effects and transport resistance within confined channels, which effectively lowers the energy barrier for perchlorate transport by 12.13 kcal/mol compared to that of sulfate. Furthermore, the sensor was optimized via substituent engineering for broad-spectrum anion detection and integrated into a portable platform for continuous on–site monitoring, achieving accuracy comparable to ion chromatography in real–world scenarios.