# Highly Sensitive Zinc Oxide Nanorods for Non-Enzyme Electrochemical Detection of Ascorbic and Uric Acids

## TL;DR

This paper introduces a simple, enzyme-free sensor using zinc oxide nanorods to detect ascorbic and uric acids with high sensitivity and selectivity.

## Contribution

The novel contribution is the potential-controlled selective detection of ascorbic and uric acids using a single ZnO electrode without complex functionalization.

## Key findings

- Heat treatment at 450 °C improves ZnO crystallinity and electrochemical performance.
- ZnO nanorods show high sensitivity to ascorbic acid (9951.87 μA·mM−1·cm−2) and uric acid (5762.48 μA·mM−1·cm−2).
- The sensor enables multicomponent detection via controlled applied potentials.

## Abstract

In this study, an enzyme-free electrochemical sensor based on zinc oxide (ZnO) nanorods synthesized by the thermal decomposition of zinc acetate is presented. The suggested approach ensures simplicity, environmental friendliness, and scalability of the process without the use of an autoclave or high pressure. The morphology and structure of the samples are studied using SEM, TEM, XRD, Raman, FTIR, XPS, PL, and UV-Vis spectroscopy. It is found that heat treatment at 450 °C increases the degree of crystallinity, increases the size of crystallites, and reduces the concentration of surface defects, which leads to improved optical and electrochemical characteristics of the material. Beyond conventional sensitivity metrics, our study demonstrates that the selective detection of ascorbic acid (AA) and uric acid (UA) can be achieved by controlling the applied potential on a single ZnO electrode, an approach that leverages differences in redox energetics and surface interaction dynamics rather than complex surface functionalization. It is shown in this work that the synthesized ZnO samples subjected to heat treatment in air at 450 °C exhibit high sensitivity to ascorbic acid (9951.87 μA·mM−1·cm−2; LoD = 1.11 μM) at a potential of 0.2 V and to uric acid (5762.48 μA·mM−1·cm−2; LoD = 1.71 μM) in a phosphate buffer solution (pH 7) at a potential of 0.4 V with a linear range of 3 mM, offering a way to create simplified multicomponent electrochemical biosensors based on potential-controlled selectivity.