Plasmonic nanozyme Cu3P with significantly enhanced peroxidase-like activity for Cr (VI) colorimetric detection

Plasmonic nanozymes with both plasmonic and biocatalytic properties stand out due to their distinctive localized surface plasmon resonance (LSPR) feature and adjustable catalytic activity, while the enhancement effect of present reported plasmon excitation remains relatively low. Here, a plasmonic nanozyme of Cu3P nanoparticles (Cu3P NPs) with LSPR characteristics and intrinsic peroxidase (POD)-like activity was prepared via simple gas-solid reaction strategy, which presents significantly enhanced POD-like activity under plasmon stimulation than that without LSPR excitation, with catalytic constants for TMB and H2O2 83 and 127 times higher than those without LSPR excitation respectively. On the one hand, the Cu3P plasmonic nanozyme generated abundant high-energy hot carriers under near-infrared (NIR) stimulation to promote cracking of H2O2 to produce plentiful reactive oxide species (ROS); on the other hand, the LSPR-induced photothermal effect on Cu3P plasmonic nanozyme greatly improves the reaction kinetics, thus making a significantly boosts POD-like activity. According to the excellent POD-like activity of Cu3P plasmonic nanozyme and 8-hydroxyquinoline (8-HQ)-mediated chromaticity switch, a highly sensitive Cr (VI) chrominance sensing platform was developed with a detection limit of 9.6 nM within a range from 0.01 to 20 μM. This study spotlights the high utilization efficiency of plasmon stimulation for enzyme-like activity tuning.