Nanoparticles of\nCu<sub>2</sub>O and TiO<sub>2</sub> on Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> Heterostructures\nfor Ultrafast Nonenzymatic Glucose Sensing

The exploration of enzyme-mimic nanocomposites to replace\ncommercial\nenzymes is challenging in the construction of biosensors with high\nperformance. Herein, an ultrafast response nonenzymatic glucose sensor\nwas developed based on a Cu<sub>2</sub>O–TiO<sub>2</sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanocomposite,\nwhich was prepared via an in situ redox procedure using Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanosheets both as a\nreducing agent and a carrier substrate. Structural characterizations,\nincluding X-ray diffraction (XRD) and transmission electron microscopy\n(TEM), revealed that Cu<sub>2</sub>O nanoparticles with a size of\n10–30 nm are uniformly distributed on the surface of the Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanosheets and\nform close contacts through Ti–O–Cu bonds, resulting\nin favorable stability of the system. The unique heterostructure of\nCu<sub>2</sub>O–TiO<sub>2</sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> can produce abundant active sites\nand facilitate electron transfer, demonstrating enhanced catalytic\nactivity in the electrooxidation of glucose. Consequently, the electrochemical\nsensor fabricated by modifying a glassy carbon electrode (GCE) with\nCu<sub>2</sub>O–TiO<sub>2</sub>/Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> nanocomposites exhibited excellent\nanalytical properties for glucose detection, including a fast response\ntime of 0.1 s, a low detection limit of 0.67 μM, and a high\nsensitivity of 267 μA mM<sup>–1</sup> cm<sup>–2</sup>. In addition, the developed method possesses good anti-interference\nability and superior stability and thus has been successfully applied\nfor real sample monitoring. This study offers a way to construct Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub>-based heterostructures\nwith tunable physiochemical properties and expands their use in the\nelectrochemical field.