Surfactant-free octahedral Cu2O@Pd nanocrystals with enhanced and multifunctional sensor performances

Abstract

Biosensing materials are often constrained by their limited functionality, narrow detection range, and restricted sensitivity. In this study, we provided a simple method to synthesize surfactant-free Cu₂O nanocrystals with octahedral structure. The distinctive octahedral structure amplified the specific surface area, thus facilitating Cu₂O nanocrystals to demonstrate an enhanced sensor performance in detecting nitrite and glucose. In the detection of sodium nitrite concentration, the sensitivity octahedral of Cu₂O surpassed that of hexapod Cu₂O in previous studies by an enhanced factor of 2.03, enabling a wide detection range from 0 to 100.0 mM. Moreover, the modification of Cu₂O nanocrystals by Pd could effectively enhance electron transfer and optimized sensor sensitivity. As the modified Pd reaches 15 at%, the Cu₂O@Pd-15 % demonstrated the highest sensitivity (303.05 μA/mM·cm²) for nitrite detection. When the Pd modification rate at the interface was exceeded to 15 at%, the active sites on the surface of Cu₂O would be covered and their quantity would be decreased, which was not conducive to further optimization of Cu₂O sensor performance. The sensor constructed by Cu₂O@Pd-15 % could detect high concentrations of glucose and directly measure the nitrite concentration in an aqueous solution, which remained a challenging for other sensor materials. Notably, Cu₂O@Pd-15 % has been successfully employed in the analysis of sugar content in Coca-Cola, showcasing its multifunctionality and practicality. This work optimized the sensor performance of Cu₂O by integrating the morphological optimization and surface modification, thereby offering an effective strategy for designing the multifunctional sensor materials.