Ion-Electron Transduction Layer of the SnS-MoS Heterojunction to Elevate Superior Interface Stability for All-Solid Sodium-Ion Selective Electrode.

The high selectivity and fast ion response of all-solid sodium ion selective electrodes were widely applied in human sweat analysis. However, the potential drift due to insufficient interfacial capacitance leads to the deterioration of its stability and ultimately affects the potential accuracy of ion analysis. Designing a novel ion-electron transduction layer between the electrode and the ion selective membrane is an effective method to stabilize the interfacial potential. Herein, the SnS-MoS heterojunction material was constructed by doping Sn in MoS nanosheets and used as the ion electron transduction layers of an all-solid sodium ion selective electrode for the first time, achieving the stable and efficient detection of Na ions. The proposed electrode exhibited a Nernst slope of 57.86 mV/dec for the detection of Na ions with a detection limit of 10 M in the activity range of 10-10 M. Via the electronic interaction at the heterojunction interfaces between SnS and MoS materials, the micro-nanostructure of the SnS-MoS heterojunction was changed and SnS-MoS as the ion-electron transduction layer acquired excellent capacitance (699 μF) and hydrophobicity (132°), resulting in a long-term potential stability of 1.37 μV/h. It was further proved that the large capacitance and high hydrophobicity of the ion-electron transduction layer are primary reasons for the excellent stability of the all-solid sodium ion selective electrode toward Na ions.