Porous hierarchical peony-like cobalt-based bimetallic oxides structured by ultrathin nanosheets for highly sensitive electrochemical pesticides detection

Efficient and sensitive electrochemical biosensors are of great significance for on-site measurement and evaluation of pesticides in the environment, and various functional nanomaterials have been designed and developed to achieve this goal. Herein, a kind of three-dimensional holey hierarchical cobalt-based bimetallic oxides randomly assembled by micro-mesoporous ultrathin nanosheets has been exploited. This unique porous hierarchical structure and bimetal composition not only possesses excellent electron pathways and consequent an enhanced electro-conductivity and better catalytic activity, but also exhibits high electroactive surface area and more vacant sites for enzyme immobilization. Along with the highly conductive and biocompatible layered graphdiyne, the 3D porous Co-based bimetallic oxides have been applied to construct an electrochemical AChE biosensor for monitoring dipterex and omethoate (as model OPs pesticides). As a result, the reported biosensor demonstrates superior sensing performance, for example, the wide detection range of 3.88 x 10- 12-3.88 x 10-6 M for diptetex and 4.69 x 10- 13-4.69 x 10-7 M for omethoate, together with the relative low detection limit of 0.36 pM and 0.033 pM (S/N = 3), respectively. Additionally, the biosensor is feasible in real samples, and the recoveries (94.8-105.1%) are satisfactory. And a possible mechanism has also been proposed. This study offers a new strategy to modulate the property of metal oxides, which make them more attractive in electrochemical sensors.