3D prickle-like hierarchical NiO nanostructures with oxygen vacancies for electrochemical detection of enrofloxacin antibiotics

Improving metal oxides intrinsic electrochemical characteristics without altering their structural or compositional elements is a challenge, especially when designing a single component-based analytical sensor for monitoring emerging pollutants. Herein we propose the induction of oxygen vacancies in hierarchical NiO nanostructures using a simple wet-chemical reduction route to improve its inherent electrochemical redox characteristics. The synthesized NiO nanostructures possessed a thistle-like morphology with nanoprickles based structural features. The 3D prickle-like nanostructures with abundant surface-oxygen vacancies realized robust redox characteristics during the electrochemical oxidation of enrofloxacin (ENF) antibiotics. The existence of oxygen vacancies in NiO (o v -NiO NPKs) increased electrochemical conductivity and elevated redox activity, resulting in a 1.46-fold increase in the oxidation response of ENF compared to its non-vacancy counterpart. The o v -NiO NPKs based sensor showed an excellent linear working response for ENF in the concentration range of 0.001 to 0.15 µM, with a detection limit of 0.12 nM. Moreover, the sensor could effectively detect ENF from environmental samples with a high recovery rate confirming its suitability for practical applications. The suggested engineering of generating oxygen vacancies in metal oxides for improving intrinsic performance opens up new avenues for developing sophisticated single-platform-based sensors for rapid and efficient monitoring of emerging environmental contaminants.