A hierarchical Cu(OH)2 nanograss-decorated bimetallic nanoporous glucose sensor with an ultra-low detection limit

Abstract

Non-enzymatic electrochemical glucose sensors, representing the fourth generation of glucose sensors, exhibit significant advantages including high response speed, resistance to biofouling, low cost, and ease of preparation. However, current glucose sensing materials face challenges such as high detection limits and poor anti-interference performance, which limit their practical applications. Herein, we have developed an innovative catalyst composed of Cu(OH)₂ nanograsses decorated on a bimetallic nanoporous structure through a simple two-step oxidation method. The resulting catalyst forms a unique sandwich-like structure, where Cu(OH)₂ nanograsses with hierarchical morphologies uniformly grow both on the external surface and within the porous channels of nanoporous CuAg. This configuration ensures the full utilization of the high specific surface area and thereby provides a high concentration of active sites, contributing to excellent catalytic performance for glucose oxidation. This developed composite catalyst demonstrates an ultra-low detection limit of 100 nM, a high sensitivity of approximately 5.16 mA mM⁻¹ cm⁻², a wide linear response range up to 8 mM, and excellent anti-interference ability. These outstanding electrocatalytic properties arise from the synergistic effect of the nanoporous CuAg's excellent conductivity and mass transfer capabilities, combined with the multiple active sites of the in situ-grown hierarchical Cu(OH)₂ nanograsses. This work highlights a unique approach to designing glucose oxidation catalysts with remarkable electrocatalytic performance, utilizing a straightforward two-step oxidation method to assemble hierarchical hydroxide morphologies, offering a promising avenue for the practical application of advanced glucose sensors.