Heavy metal ion contamination requires sensitive and selective detection methods for environmental and health monitoring. This study demonstrates that one-dimensional (1D) zinc oxide (ZnO) nanostructures with a controlled morphology enable highly sensitive photoluminescence-based detection of Cu2+ and Fe3+ ions. Three distinct ZnO morphologies─nanotetrapods, nanorods, and nanofibers─were synthesized and comprehensively characterized. ZnO nanotetrapods exhibited promising sensing performance, with detection limits of 0.92 μM for Cu2+ and 1.4 μM for Fe3+, response times of 10.6–10.9 ± 2 min, and adequate selectivity over 12 interfering metal cations. The enhanced performance correlates with nanotetrapods’ structure properties, defect chemistry, and highly negative surface charge (−42.3 mV at pH 7). We propose a sensing mechanism based on electrostatic ion adsorption followed by charge transfer that reduces Cu2+ to Cu+ and Fe3+ to Fe2+ on the ZnO surface, causing photoluminescence quenching. These findings establish the structure–property relationships for ZnO-based sensors with detection capabilities well below the WHO drinking water guidelines, demonstrating their strong potential for environmental monitoring applications.
Tepliakova et al. (2026) studied this question.