# Cu-doped In2S3 quantum dot-CeO2 nanorod hybrid electrodes via 3D nanoprinting-inspired structuring for ultrasensitive heavy metal detection

## TL;DR

A new electrochemical sensor detects heavy metals like lead, cadmium, and mercury with high sensitivity in complex fluids like blood and urine.

## Contribution

A hybrid Cu-doped In2S3 QD-CeO2 nanorod electrode structure is developed for ultrasensitive and selective heavy metal detection.

## Key findings

- The sensor detects Pb2+, Cd2+, and Hg2+ with detection limits as low as 32–60 nM.
- It achieves 95.5–99.0% recovery in artificial serum and synthetic urine with RSD < 4.5%.
- The electrode structure enables broad linear detection range (0.1 nM to 50 µM) and rapid charge transfer.

## Abstract

Sensitive and selective detection of toxic heavy metals in complex matrices is essential for both clinical diagnostics and environmental monitoring. Herein, we present a nanostructured electrochemical sensor based on Cu-doped In2S3 quantum dots (QDs) anchored onto oxygen-vacancy-rich CeO2 nanorods, fabricated through a 3D nanoprinting-inspired electrode structuring strategy that provides precise control over morphology and active surface accessibility. The synergistic integration of Cu:In2S3 QDs, supplying abundant catalytic sites, with CeO2 nanorods, facilitating rapid charge transfer, significantly enhanced the electrocatalytic performance toward Pb2+, Cd2+, and Hg2+ detection. Differential pulse voltammetry (DPV) enabled simultaneous monitoring with well-resolved anodic peaks (150–200 mV separation), broad linear range (0.1 nM to 50 µM), and low detection limits down to 32–60 nM. Electrochemical impedance spectroscopy confirmed reduced charge transfer resistance (∼150 Ω), consistent with accelerated interfacial kinetics. Importantly, the sensor showed strong resilience in ISO 15189-compliant artificial serum and synthetic urine, achieving recoveries of 95.5–99.0% with RSD < 4.5%. This work demonstrates how synergistic nanocomposite chemistry combined with advanced electrode structuring can deliver scalable and robust electrochemical platforms for real-time heavy metal detection in biomedical and environmental applications.

3D-nanoprinted Cu:In2S3 QD-CeO2 nanorod electrodes enable simultaneous ultrasensitive detection of Pb2+, Cd2+, and Hg2+ (LODs 32–60 nM) in serum/urine with 95.5–99.0% recovery, via synergistic catalysis and enhanced surface accessibility.