Cu-Doped ZnS-Modified Ni ₃ S ₂ Nanosheets on Ni Foam for Non-Enzymatic Glucose Sensing

The growing prevalence of diabetes mellitus drives the urgent demand for reliable glucose monitoring technologies. Herein, we report a self-supported nonenzymatic glucose sensor based on Cu-doped ZnS-modified Ni 3 S 2 nanosheets (Cu-doped ZnS/Ni 3 S 2 ) with amorphous–crystalline heterostructure directly grown on a three-dimensional nickel foam. The rationally engineered electrode integrates multiple synergistic merits: crystalline Ni 3 S 2 nanosheets offer abundant catalytic sites, amorphous ZnS improves the recognition and adsorption of glucose molecules, and Cu doping promotes the generation of electroactive Ni 3+ species while tailoring the electronic structure of Ni 3 S 2 . Density functional theory calculations reveal that Cu incorporation improves glucose adsorption on the sensor and reduces the energy barrier of the rate-determining step from 0.27 to 0.08 eV by optimizing the adsorption free energy of key intermediates (i.e., *C 6 H 12 O 6, *C 6 H 11 O 6, and *C 6 H 10 O 6 ). Benefiting from this architecture, the sensor exhibits superior performance with a high sensitivity of 22.16 mA mM –1 cm –2 (detection range = 0.001–1 mM), an ultralow detection limit of 0.37 μM, rapid response (∼2 s), excellent stability, and strong anti-interference capability. Our results not only underscore the synergy among the components and dopant in the reported composite but also serve as a necessary reference and inspiration for the rational design of advanced nonenzymatic glucose sensing materials.