Porous Co3O4 nanodisks as robust peroxidase mimetics in an ultrasensitive colorimetric sensor for the rapid detection of multiple heavy metal residues in environmental water samples

The current method for rapid and ultrasensitive detection of multiple heavy metals in environmental water still face challenge. Herein, the porous Co3O4 nanodisks with robust peroxidase-mimicking activity were prepared, and its catalytic activity can be significantly inhibited by the heavy metals like Cd(II), Hg(II), Pb(II) and As, which makes us to establish an ultrasensitive and rapid colorimetric sensor for the detection of multiple heavy metals. Further investigation reveals the anticompetitive inhibition effect of heavy metals on peroxidase-mimicking activity. The colorimetric sensor displays excellent sensitivity and selectivity, and the limits of detection (LOD) for Cd(II), Hg(II), Pb(II) and As are 0.085 μg·L-1, 0.19 μg·L-1, 0.2 μg·L-1 and 0.156 μg·L-1, respectively. Notably, the absorbance variation will be greater than 0.5 as the concentration of heavy metals exceeds 5 μg·L-1, which can be clearly discriminated by the naked eyes. Moreover, the average recovery range of heavy metals in actual water samples is from 86.9% to 98.3%. The above results indicate that the proposed sensor exhibits excellent practical applicability for the rapid and ultrasensitive detection of multiple harmful heavy metals in several environmental water samples, which has potential bright application in protecting the environment and human health.