Copper Selenide Micro/Nanocrystals on Carbon Paper via Chemical Vapor Deposition Selenylation as Electrodes for Non-enzymatic Glucose Sensing

Glucose is a vital monosaccharide for catabolism, but its imbalances can lead to diabetes, a chronic disease without a cure but manageable through diet and lifestyle changes. For people with diabetes, timely monitoring of glucose level is very important for treatment. This can be done by various glucose sensors. However, the rational design and controllable synthesis of glucose catalysts with low-cost and high-efficiency glucose detection ability are still challenging. Herein, copper selenide micro/nanocrystal-modified carbon paper (Cu_2–xSe/CP) self-supporting electrodes were prepared by a facile electrodeposition method followed by chemical vapor deposition. The rod-shaped carbon substrate and shale-shaped Cu_2–xSe micro/nanoparticles resulted in the formation of a hierarchical structure. The synergistic effects between Cu_2–xSe active sites and carbon paper promoted electronic transfer, resulting in an enhanced electrocatalytic performance for glucose oxidation. The optimized Cu_2–xSe/CP exhibited excellent glucose sensing performance with linear detection ranges of 5–200 and 200–760 μM, as well as high sensitivities of 5391 μA mM^–1 cm^–2 at low glucose concentrations and 3004 μA mM^–1 cm^–2 at high concentrations with a low detection limit of 1.2 μM (S/N = 3). In addition, Cu_2–xSe/CP exhibited excellent reproducibility, stability, anti-interference, and long-term storage ability. The practical applications of Cu_2–xSe/CP were evaluated by measuring glucose in real human serum samples and artificial saliva, and the results displayed an outstanding performance. In sum, the proposed Cu_2–xSe/CP-modified electrode with excellent glucose electrocatalytic activity is very promising for future clinical non-enzymatic glucose detection.