NiCoZn Oxide Nanocages\non Reduced Graphene Oxide Nanosheets\nfor the Electrochemical Detection of Luteolin

Mixed metal oxides derived from a metal–organic\nframework\n(MOF) sacrificial template take advantage of the original morphology\nof MOFs, excellent electrocatalytic properties, mesoporous structure,\nand more active sites and transport channels, which is favorable to\nconstruct a high-performance electrochemical sensor. Here, polyhedral\nCoZn-MOFs are synthesized by precipitation at room temperature, and\nthen they are etched using Ni<sup>2+</sup> to obtain hollow polyhedral\nNiCoZn hydroxide (NiCoZn-OH) nanocages. After self-assembly with graphene\noxide (GO) nanosheets and annealing, the hollow polyhedral NiCoZn\nmixed metal oxide/reduced graphene oxide (NiCoZnO<sub>X</sub>/rGO)\nmixture with a size of ∼700 nm is obtained and used for electrochemically\ndetecting luteolin (LU), which shows a high sensitivity (7.16 μA·μM<sup>–1</sup>·cm<sup>–2</sup> in 0–60 μM)\nand a low limit of detection (64 nM, S/N = 3). Moreover, it has excellent\nselectivity in the presence of ascorbic acid and is successfully used\nto detect LU in diluted human urine, indicating a great potential\nin clinical applications.