Highly efficient construction of heterojunction Co3O4/NiMoO4 hierarchical arrays with built-in electric field enabling ultrasensitive glucose sensing

The accurate non-enzymatic electrochemical detection of glucose is constrained by sluggish charge transfer kinetics and non-optimized adsorption of reaction intermediates on single-phase transition metal oxide. Herein, we rationally design heterojunction Co 3 O 4 /NiMoO 4 hierarchical arrays, where a spontaneous built-in electric field (BEF) is formed at the p-n hereo-interface due to the precise work function difference in NiMoO 4 and Co 3 O 4 . This BEF directionally drives electrons from NiMoO 4 to Co 3 O 4 at 0.16 |e|, as confirmed by DFT charge density and Bader charge analysis, thereby accelerating glucose electrocatalytic oxidation kinetics. Moreover, the hierarchical structure of Co 3 O 4 nanoneedles grown on NiMoO 4 nanorods enhances the electrochemical active area and introduces dual catalytic sites of Co and Ni atoms, whose d-band centers are modulated to weaken excessive adsorption at Co sites while maintaining Ni activity. As a results, the assembled sensor achieves an ultrahigh sensitivity of 28,470 μA mM −1  cm −2 , a low detection limit of 0.396 μM and excellent recovery rates (94.6%–105.6%) in complex real samples. This work demonstrates that resolving the charge transfer and adsorption trade-off via BEF-engineered heterostructure offers a generalizable route for high-performance sensing. Download: Download high-res image (156KB) Download: Download full-size image