Heterojunction-induced interface barrier modulation in ZnO@Zn-HHTP for dopamine detection

Rational modulation of interfacial charge-transfer processes is critical for advancing the performance of electrochemical sensors, yet precise control of heterojunction-induced potential barriers for selective molecular recognition remains challenging. Herein, we report a ZnO@Zn-2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) core-shell heterostructure that enables highly selective detection of dopamine (DA) via analyte-responsive modulation of an interfacial potential barrier. The heterostructure is synthesized through an in-situ conversion strategy, transforming a ZIF-8 shell on ZnO nanorods into Zn-HHTP while preserving the core-shell architecture. The resulting ZnO/Zn-HHTP interface forms a well-defined n-p heterojunction with a built-in potential barrier that governs charge-transfer kinetics. Positively charged DA induces interfacial charge redistribution at the negatively charged Zn-HHTP surface, lowering the barrier height and facilitating electron transfer, thereby amplifying the electrochemical signal. In contrast, common interferents induce negligible response, as they are unable to modulate the interfacial potential barrier and do not undergo effective electrochemical reaction at the characteristic redox potential of dopamine, thereby enabling selective detection. The sensor displays a wide linear range (50 nM-300 μM) and a low detection limit of 16.7 nM, which demonstrates reliable performance in the detection of target in human urine samples. This work highlights interfacial barrier modulation as an effective strategy for designing high-performance electrochemical sensors based on conductive MOF-semiconductor heterostructures.