Grain boundary/doping/architecture engineering in hierarchical N-doped CuO microflowers derived from Cu-based...

Glucose detection is essential in clinical medicine, and the reasonable design of metal oxide electrocatalysts plays a crucial role in developing efficient nonenzymatic glucose (NEG) sensors. Herein, grain boundary/doping/architecture engineering is used to tailor the structures of CuO nanomaterials and tune their surface/electron-transfer properties toward enhanced electrocatalytic oxidation of glucose. Hierarchical N-doped CuO microflowers (N-CuO-MF) are synthesized using a facile hydrothermal method, followed by calcination. N-CuO-MF consist of ultrathin nanoflakes (ca. 20 nm), endowing them with a large specific surface area. Moreover, the nanoflakes are composed of ultrasmall nanoparticles, resulting in abundant grain boundaries. Notably, N-CuO-MF are derived from a precursor of Cu-based metal-organic framework (Cu-MOF) architectures, which is fabricated through a bottom-up route using glycerol as the capping agent/solvent and 1-hexadecyl-3-methylimidazolium bromide ([C₁₆mim]Br) as the template/N source. Glycerol competitively coordinates with Cu²⁺, leading to the formation of 2D subunits. Moreover, [C₁₆mim]⁺ cations attach to the subunit surfaces via electrostatic interaction, thus achieving Cu-MOF with a 3D hierarchical structure. As expected, the synergistic effect of rich grain boundaries, N doping, ultrathin nanoflakes, and hierarchical architecture enhances the adsorption of glucose on the electrode surfaces, accelerates electron transfer, and exposes more active sites for glucose oxidation. Accordingly, N-CuO-MF exhibit wide linear ranges, high sensitivity, fast response time, low detection limit, excellent selectivity, and good stability. Owing to their highly efficient electrocatalytic properties, N-CuO-MF could be explored as potential electrocatalysts in NEG sensors for rapid diagnostic tests and health monitoring.