Interface-Engineered β-Ni(OH)₂/MXene Heterostructure for Electrochemical Detection of Ascorbic Acid

Rational heterostructure engineering in tuning electrochemical performance is demonstrated by developing a β-Ni(OH)₂/MXene interface-engineered nanocomposite for sensitive ascorbic acid (AA) detection. The nanocomposite is synthesized via a facile sonication-assisted mechanical stirring approach, enabling robust heterointerfacial coupling. Structural and spectroscopic analyses indicate that the enhanced electrochemical performance originates from the nanocomposite architecture, in which strong electronic metal–support interactions, likely via Ti–O···Ni linkages and a higher number of electroactive Ni³⁺ species, regulate charge-transfer dynamics and catalytic activity. Ferricyanide/ferrocyanide redox probe studies reveal synergistically enhanced electrochemical behavior compared with the pristine components, confirming improved interfacial charge-transfer kinetics. The optimized β-Ni(OH)₂/MXene (1:2) electrode exhibits a homogeneous distribution, increased electrochemically active surface area, and reduced charge-transfer resistance. This engineered interface promotes rapid electron transfer and efficient Ni²⁺/Ni³⁺ redox cycling, thereby enhancing electrocatalytic activity toward AA oxidation. The sensor achieves a fast response time (∼1 s), a low detection limit of 54 nM, and a wide linear detection range from 0.01 μM to 1000 μM. It also demonstrates excellent selectivity against common interfering species and reliable performance in pharmaceutical real-sample analysis. These findings establish interfacial bond engineering as a critical design strategy for MXene-based nanocomposites, offering new insights into the development of high-performance nonenzymatic electrochemical sensors.