Boosting sensitive and selective detection toward Pb(II) via activation effect of Co and orbital coupling between Pb and O over Co@Co3O4 nanocatalyst.

ABSTRACT

Fruitful achievements on electrochemical detection toward Pb(II) have been achieved, and their good performance is generally attributed to the adsorption property of nanomaterials. However, the design of sensing interfaces from the electronic structure and electron transfer process is limited. Here, Co@Co3O4 acquired an ultra-high detection sensitivity of 103.11 µA µM-1 toward Pb(II), outperforming the results previously reported. The interfacial oxygen atoms build an electron bridge for Co activating Co3O4. Particularly, new energy levels of oxygen atoms were generated and matched with that of Pb(II). The strong orbital coupling effect between O and Pb makes the Co@Co3O4 sensitive and selective toward Pb(II). Compared with Co metal and Co3O4, Pb(II) got more electrons from Co@Co3O4, and longer Pb-O bonds were formed, allowing more Pb(II) to be catalyzed and reduced. Also, the superior stability and reproducibility of electrochemical detection make electrodes practicably. This work reveals that metals can stimulate intrinsically catalytic activity of their metal oxides, with the generation of orbit energy levels that match to a specific analyte. It provides a promising strategy for constructing sensitive and selective sensing interfaces toward ultra-low concentration analyte in body fluid and other complex samples.